[Federal Register Volume 76, Number 92 (Thursday, May 12, 2011)]
[Proposed Rules]
[Pages 27756-27799]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-11056]
[[Page 27755]]
Vol. 76
Thursday,
No. 92
May 12, 2011
Part II
Department of the Interior
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Fish and Wildlife Service
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50 CFR Part 17
Endangered and Threatened Wildlife and Plants; Withdrawal of the
Proposed Rule To List the Mountain Plover as Threatened; Proposed Rule
Federal Register / Vol. 76 , No. 92 / Thursday, May 12, 2011 /
Proposed Rules
[[Page 27756]]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R6-ES-2010-0038; MO 92210-0-0008-B2]
RIN 1018-AX26
Endangered and Threatened Wildlife and Plants; Withdrawal of the
Proposed Rule To List the Mountain Plover as Threatened
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Proposed rule; withdrawal.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce our
decision to withdraw the proposed listing of the mountain plover
(Charadrius montanus) as a threatened species under the authority of
the Endangered Species Act of 1973, as amended (Act). After a thorough
review of all available scientific and commercial information, we have
determined that the species is not endangered or threatened throughout
all or a significant portion of its range. We make this determination
because threats to the species as identified in the proposed rule are
not as significant as earlier believed and currently available data do
not indicate that the threats to the species and its habitat, as
analyzed under the five listing factors described in section 4(a)(1) of
the Act, are likely to endanger the species in the foreseeable future
throughout all or a significant portion of its range.
DATES: The December 5, 2002 (67 FR 72396), proposal to list the
mountain plover as a threatened species is withdrawn as of May 12,
2011.
ADDRESSES: This finding is available for viewing on the Internet at
http://www.regulations.gov (see Docket No. FWS-R6-ES-2010-0038) and
http://www.fws.gov/mountain-prairie/species/birds/mountainplover and
also by appointment, during normal business hours, at the U.S. Fish and
Wildlife Service, Colorado Ecological Services Office, 134 Union
Boulevard, Suite 670, Lakewood, CO 80225; telephone 303-236-4773;
facsimile 303-236-4005. Please submit any new information, materials,
comments or questions concerning this finding to the Colorado
Ecological Services Field Office at P.O. Box 25486, DFC (MS 65412),
Denver, Colorado 80225.
FOR FURTHER INFORMATION CONTACT: Susan Linner, Field Supervisor, U.S.
Fish and Wildlife Service, Colorado Ecological Services Field Office
(see ADDRESSES). If you use a telecommunications device for the deaf
(TDD), call the Federal Information Relay Service (FIRS) at 800-877-
8339.
SUPPLEMENTARY INFORMATION:
Background
Previous Federal Actions
For a detailed description of Federal actions concerning the
mountain plover, please refer to the February 16, 1999, proposed rule
to list the species (64 FR 7587); the December 5, 2002, proposed rule
to list the species with a special rule under section 4(d) of the Act
(16 U.S.C. 1531 et seq.) (67 FR 72396); and the September 9, 2003,
withdrawal of the proposed rule to list the species (68 FR 53083).
The document we published on September 9, 2003 (68 FR 53083),
withdrew the entire proposed rule we published on December 5, 2002 (67
FR 72396), including our proposal to list the mountain plover as a
threatened species and our proposed special 4(d) rule. The September 9,
2003, document also addressed comments we received on both the 1999 and
2002 proposals to list the mountain plover and summarized threat
factors affecting the species. The withdrawal of the proposed rule was
based on our conclusion that the threats to the mountain plover
identified in the proposed rule were not as significant as previously
believed and that currently available data did not indicate that
threats to the species and its habitat, as analyzed under the five
listing factors described in section 4(a)(1) of the Act, were likely to
endanger the species in the foreseeable future throughout all or a
significant portion of its range.
On November 16, 2006, Forest Guardians (now WildEarth Guardians)
and the Biological Conservation Alliance filed a complaint in the
District Court for the Southern District of California challenging the
September 9, 2003, withdrawal of the proposal to list the mountain
plover (68 FR 53083). We entered into a settlement agreement with the
plaintiffs, which was filed by the court on August 28, 2009. As part of
the settlement agreement, we agreed to reconsider our decision to
withdraw the proposed listing of the mountain plover and to submit to
the Federal Register by July 31, 2010, a document reopening the
December 5, 2002, proposal to list the mountain plover (67 FR 72396)
that would also request public comments. We agreed to vacate our 2003
withdrawal of the proposed rule upon publication of the Federal
Register notice reopening public comment on the December 5, 2002,
proposal to list the mountain plover (67 FR 72396). We further agreed
to submit a final listing determination for the mountain plover to the
Federal Register no later than May 1, 2011.
On June 29, 2010, we published a document in the Federal Register
notifying the public that we were reinstating that portion of our
December 5, 2002, proposed rule to list the mountain plover as
threatened under the Act (75 FR 37353). We did not reinstate that
portion of the December 5, 2002, proposed rule regarding a proposed
special rule under section 4(d) of the Act. The proposed special rule
was designed to allow researchers to complete field research and
analyze data for an ongoing study, and addressed agricultural
activities only through December 31, 2004. To ensure that our review of
the species' status was complete and based on the best available
scientific and commercial information, we requested comments on the
proposal to list the mountain plover as a threatened species, including
all information related to the species' status and the proposed
listing. We invited public comments on the proposed listing, new
information relevant to our consideration of the status of the mountain
plover, and comments and information regarding threats to the species
and its habitat.
Species Information
Our February 16, 1999, and December 5, 2002, proposed rules (64 FR
7587 and 67 FR 72396, respectively), and our September 9, 2003,
withdrawal of our 2002 proposal to list the mountain plover (68 FR
53083) described the species' life history, ecology, and habitat use.
For additional background on the natural history of the mountain
plover, see the account of the species in The Birds of North America
(Knopf and Wunder 2006).
While the majority of relevant information directly pertaining to
the mountain plover that has become available since our December 5,
2002, proposal to list (67 FR 72396) and September 9, 2003, withdrawal
of that proposal (68 FR 53083) has resulted from local or Statewide
studies on the mountain plover's breeding range; two recent documents
provide extensive review of current knowledge regarding the mountain
plover:
(1) Mountain Plover (Charadrius montanus) in Birds of North America
(Knopf and Wunder 2006); and
(2) Conservation Plan for the Mountain Plover (Charadrius
montanus), Version 1.0 (Andres and Stone 2009).
[[Page 27757]]
Numerous other recent documents are summarized in our June 29,
2010, notification reinstating our December 5, 2002, proposed rule to
list the mountain plover as threatened under the Act (75 FR 37353).
These include over twenty peer-reviewed journal articles, and many
other reports and summaries relevant to the status of the mountain
plover that have become available since 2002.
The following sections highlight and update information on the
mountain plover with emphasis on information developed since 2002.
Taxonomy and Species Description
The mountain plover (Charadius montanus) is a small bird in the
order Charadriiformes, family Charadriidae. No subspecies are
recognized. It is a migratory, terrestrial shorebird averaging 8 inches
(21 centimeters) in body length. Mountain plover are light brown above
and white below, but lack the contrasting dark breast band
characteristic of several other plovers such as the more common
killdeer (C. vociferus). Sexes are similar in appearance.
Feeding Habits
Mountain plover feed on ground-dwelling invertebrates and flying
invertebrates found on the ground, primarily beetles, crickets, and
ants. They forage with a series of short runs and stops, feeding
opportunistically as they encounter prey (Knopf and Wunder 2006,
unpaginated).
Breeding
Mountain plover return north to their breeding sites in the western
Great Plains and Rocky Mountain States in spring. They arrive at their
breeding grounds in northeastern Colorado in late March (Graul 1975, p.
6). Arrival is earlier farther south and later in Montana and at higher
elevations in South Park, Colorado (Knopf and Wunder 2006). Mountain
plover are territorial during the breeding season, with males defending
territories shortly after arrival (Knopf and Wunder 2006). Mountain
plover are generally monogamous; they form pairs and begin courtship on
arrival at their breeding grounds. Nests consist of a simple ground
scrape. Egg laying in northeastern Colorado begins in late April and
extends through mid-June (Graul 1975, p. 7). Graul (1973, p. 84)
described mountain plover nesting as a ``rapid multi-clutch system.''
The female normally produces two clutches, typically three eggs each,
at different nest sites; the male incubates the first nest site while
the female incubates the second. If the first nest or brood is lost
early in the breeding season, the adult may renest, so each pair can
potentially make four attempts per year to raise a brood. This breeding
system may increase breeding success given predation that occurs on
mountain plover nests or broods. This breeding system, rare among bird
species, may result in greater reproductive potential than in other
shorebirds (Knopf and Wunder 2006). It may have developed in response
to food fluctuations that typically occur in the shortgrass prairie,
where insect populations likely fluctuate in response to annual,
seasonal, and local fluctuations in precipitation (Graul 1973, p. 85).
Average incubation period is 29 days (Graul 1975, p. 19). Chicks
leave the nest within hours of hatching and obtain their own food. Only
one adult normally tends each nest and brood. The minimum habitat
requirement for mountain plover broods in Montana was 70 acres (ac) (28
hectares (ha)) (Knopf and Rupert 1996, p. 33), and brood home ranges
averaged 143 ac (57 ha) on rangeland in Colorado (Knopf and Rupert
1996, p. 31). Brood home ranges appeared similar for three Colorado
landscapes (Dreitz and Knopf 2007, p. 129). Parents stay with chicks
until they fledge, which occurs at about 33 to 34 days (Graul 1975, p.
25). Mountain plover breed their first spring and every year thereafter
(Knopf and Wunder 2006).
Habitat and Range
Although often thought of as a grassland species, the mountain
plover may best be described as a species of disturbed prairie or semi-
desert habitat (Knopf and Miller 1994, p. 505). They are found on open,
flat lands including xeric (extremely dry) shrublands, shortgrass
prairie, barren agricultural fields, and other sparsely vegetated
areas. On grasslands, they often inhabit areas with a history of
disturbance by burrowing rodents such as prairie dogs (Cynomys spp.),
native herbivores, or domestic livestock.
Mountain plover breed from Canada (extreme southern Alberta and
Saskatchewan) to northern Mexico (Figure 1) with greatest apparent
numbers in Colorado and Wyoming, and substantial numbers in Montana,
New Mexico, and Nebraska. In Mexico, breeding populations are suspected
in the States of Chihuahua, Cohuila, and Nuevo Leon (Andres and Stone
2009, p. 9).
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Mountain plover winter in similar habitat, many in California, but
also in southern portions of Arizona, Nevada, New Mexico, Texas, and in
northern Mexico. While California's Sacramento, San Joaquin, and
Imperial Valleys support the greatest documented concentrations of
wintering mountain plover, relatively little is known about wintering
numbers or distribution in other areas.
Breeding Habitat
Common elements of mountain plover breeding habitat include short
vegetation, bare ground, and flat topography. The mountain plover
historically nested in a region impacted by a variety of herbivores,
including prairie dogs, bison (Bison bison), and pronghorn antelope
(Antilocapra americana), because these heavily grazed or similarly
disturbed landscapes support reduced height and density of vegetation,
creating favorable breeding habitat for mountain plover. While the
mountain plover is categorized as a shorebird, it is seldom found near
margins of freshwater or marine estuaries. Dinsmore (2003, pp. 14-17)
described four types of breeding habitat: Short- and mixed-grass
prairie, prairie dog colonies, agricultural lands, and semi-desert.
[[Page 27759]]
On the plains, the mountain plover is generally considered an
associate of the shortgrass prairie, dominated by blue grama (Bouteloua
gracilis) and buffalo grass (Buchloe dactyloides) (Knopf and Miller
1994, p. 504). In the Pawnee National Grasslands (PNG) in northern Weld
County, Colorado, an area that formerly supported the greatest known
concentration of breeding mountain plover, breeding habitat was
described as restricted to flat, heavily grazed areas (Graul 1973, p.
69). Native prairie grasslands formerly presented a diverse ecosystem,
shaped by low precipitation, grazing, and fire. Today, prairie
landscapes often consist of grassland fragments where current cattle
grazing practices tend to create relatively uniform grass coverage and
height, which is not beneficial to mountain plover (Knopf 2008, pp. 55-
57). Typical range management practices such as rotational grazing,
limited grazing, and improving soil moisture are designed to promote
taller grasses that limit mountain plover use. Within these landscapes,
areas of cattle concentration (loafing areas and near water),
disturbance caused by prairie dogs, and plowed or fallow (unseeded for
one or more seasons) agricultural fields create conditions favorable
for mountain plover nesting (Knopf and Wunder 2006). Mountain plover
are also attracted to burned areas in their breeding grounds, and
burning may be valuable as a habitat management tool (Knopf 2008, pp.
25-26, 57-58, 61; Andres and Stone 2009, p. 34).
Prairie dog colonies create important habitat for mountain plover,
and are especially important to maintaining mountain plover populations
in the northern portions of their range (Dinsmore et al. 2003, pp.
1024-1025; Dinsmore et al. 2005, p. 1552; Augustine et al. 2008,
unpaginated; Childers and Dinsmore 2008, p. 705; Tipton et al. 2009,
pp. 496-497; Dreitz 2009, pp. 875-877). Active prairie dog colonies
provide exposed soils around burrows and, because prairie dogs keep
surrounding vegetation clipped, an area of low-growing, perennial
vegetation that is suitable as mountain plover breeding and brood-
rearing habitat. In addition, prairie dogs give alarm calls in response
to the approach of predators and may alert mountain plover to predator
presence. The density of mountain plover was found to be much greater
on black-tailed prairie dog (C. ludovicianus) colonies than on other
habitats in Montana (Childers and Dinsmore 2008, pp. 705-706). In
north-central Montana, the size of the adult mountain plover population
closely tracked annual changes in the area occupied by black-tailed
prairie dogs (Dinsmore et al. 2003, p. 1024). Both prairie dog and
mountain plover numbers declined sharply in the mid-1990s in response
to an outbreak of sylvatic plague, which caused deaths of prairie dogs
and resultant loss of favored mountain plover habitat. Mountain plover
later increased in concert with subsequent increases in prairie dogs
(Dinsmore et al. 2005, pp. 1550-1552).
In the Colorado shortgrass prairie ecosystem, mountain plover
densities observed on black-tailed prairie dog colonies were higher
than those on dryland agriculture and much higher than those on
grasslands without prairie dogs (Dreitz et al. 2006, p. 702; Tipton et
al. 2009, p. 496). Mountain plover were significantly more abundant on
black-tailed prairie dog colonies than on other rangeland within a
bison pasture in northeastern New Mexico (Groguen 2010, pers. comm.).
Prairie dog colonies occupied by mountain plover were, on average,
larger in size than colonies with no mountain plover. In Utah, mountain
plover nested in proximity to white-tailed prairie dog (C. leucurus)
colonies (Manning and White 2001, p. 226). In northeastern Mexico,
breeding mountain plover were associated with Mexican prairie dog (C.
mexicanus) colonies (Gonzales-Rojas et al. 2006, p. 82).
Mountain plover have been found to regularly use fallow or plowed
agricultural fields for nesting (Shackford et al. 1999, entire; Dreitz
and Knopf 2007, pp. 684-685; Bly et al. 2008, p. 127; McConnell et al.
2009, pp. 30-33). Where mountain plover have an opportunity to choose
between agriculture and prairie, they may use both equally (Knopf and
Rupert 1999, p. 84). Shackford et al. (1999, entire) found mountain
plover nesting on cultivated fields in Colorado, Oklahoma, Kansas, and
Wyoming. Fifty percent of all nests they encountered during their
research were on fallow or bare fields. While many nests were destroyed
by farm machinery, they concluded that mountain plover were using
cultivated fields successfully for nesting, especially in southern
portions of the species' range (Shackford et al. 1999, p. 117).
Recent studies addressed the mountain plover's nesting ecology, and
attempted to identify the extent of breeding distribution and
population size in Nebraska (Bly et al. 2008). They encountered 272
nests on agricultural fields of cultivated wheat and millet (Bly et al.
2008, p.123). Studies in Oklahoma encountered mountain plover on bare
agricultural fields (90 percent of observations), with few (5 percent
of observations) associated with prairie dog towns (McConnell et al.
2009, pp. 31-32).
It remains unknown whether Texas or Mexico crop fields support
mountain plover breeding (Andres and Stone 2009, p. 24). Holliday
(2010) reported that breeding season sightings of mountain plover from
the Texas Panhandle tended to be in cultivated fields as in adjacent
Oklahoma, although previously reported nesting in West Texas was in
grazed, short-grass habitat.
Knopf and Wunder (2006) described mountain plover as breeding
``more predictably'' at semi-desert locations west of the shortgrass
prairie in Colorado, Wyoming, and Montana. Beauvais and Smith (2003,
entire) developed a model of mountain plover breeding habitat in shrub-
steppe habitat of western Wyoming. They related favored patches of
mountain plover breeding habitat to poor soils, low precipitation, and
wind scour, features they predicted would persist over time, especially
on public lands. In such habitats, mountain plover are less dependent
on prairie dog colonies to create breeding habitat. A Wyoming study
located 55 mountain plover nests in grassland or desert scrub habitat
in six counties (Plumb et al. 2005a, p. 225). All nest sites were
grazed by ungulates with prairie dogs present at only 36 percent of
nest sites, mostly in grassland (Plumb et al. 2005a, pp. 226-227). In
Montana, Childers and Dinsmore (2008, p. 107) noted that sparsely
vegetated, hardpan clay flats provided nesting habitat.
In summary, mountain plover require short vegetation with some bare
ground on their breeding sites. In grasslands, this usually requires
disturbance, such as that provided by prairie dogs, cattle grazing,
fire, or farming. In semi-desert environments, breeding habitat may
persist without these forms of disturbance.
Migration and Wintering Habitat
Southbound migration of mountain plover is prolonged, with post-
breeding flocks numbering in the hundreds forming in late June with
some remaining on breeding areas until September or October (Bly et al.
2008, p. 123; Andres and Stone 2009, p. 10). Mountain plover migrate
southward across the southern Great Plains in late summer and early
fall to Texas, New Mexico, and Mexico, with many then traveling west to
California (Knopf and Wunder 2006). During spring migration, mountain
plover move from their
[[Page 27760]]
wintering sites in early March and proceed quickly to breeding sites in
eastern Colorado by mid-March and in Montana by mid-April (Knopf and
Wunder 2006). Mountain plover are generally thought to use habitats
similar to those on the breeding and wintering grounds during
migration. During migration, they have also been reported using
alkaline or mud soils, and sod farms (Knopf and Wunder 2006). Few
studies have been conducted on stopover habitat, and little is known
about stopover ecology or food resources exploited (Andres and Stone
2009, pp. 14, 21, 37).
In winter, mountain plover use habitats similar to those on their
breeding grounds. Mountain plover are found wintering in California
mostly on fallow and cultivated agricultural fields, but also on
grasslands and grazed pastures (Hunting et al. 2001, p. 39; Knopf and
Wunder 2006).
Throughout the Central Valley of California, the field types used
by mountain plover vary seasonally, from uncultivated lands in October
and November, shifting toward cultivated lands over the winter (Hunting
and Edson 2008, pp. 183-184). Mountain plover wintering in the San
Joaquin Valley of California used tilled fields, grazed pastures,
alkali flats, and burned fields, but they preferred native valley sink
scrub (low vegetation dominated by alkali-tolerant shrubs) and
nonnative grazed or burned grasslands over any of the more common
cultivated land types (Knopf and Rupert 1995, pp. 747-749). Winter
habitat availability in California's Carrizo Plain seems linked to a
combination of livestock grazing and precipitation, with heavy grazing
and dry conditions creating conditions most favorable to the mountain
plover. Giant kangaroo rat (Dipodomys ingens) precincts (colonies) are
also used, especially when wet years produce tall vegetation elsewhere
(Sharum 2010, pers. comm.).
Mountain plover exclusively used cultivated sites in the Imperial
Valley of California (Wunder and Knopf 2003, pp. 74-75). While
cultivated lands are abundant throughout the Imperial Valley, not all
provide suitable feeding habitat. Mountain plover were found to favor
irrigated farmland, including burned bermudagrass (Cynodan dactylon);
harvested, grazed, or sprouting alfalfa (Medicago spp.) fields; and
newly cultivated fields (Wunder and Knopf 2003, pp. 75-76; AMEC Earth
and Environment 2003, p. 12). Fallow fields were used mostly for
roosting, and melon and vegetable fields were rarely or never used
(Wunder and Knopf 2003, pp. 75-76). Insect availability, furrow depth,
size of dirt clods, and the vegetation on contiguous land parcels were
all believed to influence the suitability of agricultural fields to
mountain plover.
In California, annual climatic variability, especially abundant
rainfall, influences field conditions and can reduce mountain plover
use of traditionally occupied wintering sites. For example, mountain
plover became virtually absent from cultivated fields in the Imperial
Valley during the rainy winter of 2004-2005 (Knopf and Wunder 2006).
Movement patterns of wintering mountain plover in California are shown
to be highly variable, with birds on several occasions moving more than
34 miles (mi) (55 kilometers (km)) in a week (Knopf and Wunder 2006).
In Arizona, mountain plover winter on sod farms and grazed
pastures, and are observed using the same sites yearly. Their use of
farm fields and other potential habitats is generally unknown, and
these areas are rarely surveyed (Robertson 2010, p. 1). A few mountain
plover have wintered in recent years on mowed grasses at Gila Bend Air
Force Auxiliary Field (Mendelsohn 2010).
In Texas, winter reports of mountain plover were correlated with
barren fields and grazed pastures (Holliday 2010). In Williamson and
Bell Counties, Texas, mountain plover winter only on large, flat,
plowed fields, especially those with some corn or sorghum stubble
(Fennel 2002, p. 29). In the Texas coastal bend area (Nueces and San
Patricio Counties), wintering plover are largely limited to plowed
fields rather than grasslands or fallow fields, with mountain plover
often following tractors while feeding (Cobb 2009, pers. comm.).
Wintering mountain plover in Texas have also been reported using burned
fields (Knopf and Wunder 2006), sod farms (Cobb 2011, pers. comm.),
coastal prairies, and alkaline flats (Andres and Stone 2009, p. 12).
In Mexico, mountain plover are found wintering in grassland areas
with high densities of prairie dogs (both black-tailed and Mexican) and
on heavily grazed pastures (Andres and Stone 2009, p. 12; Macias-Duarte
and Panjabi 2010, pp. 5, 7). Consistent with other areas, open habitat
with low grass cover and sparse or no shrub cover are elements common
to areas used by mountain plover in Mexico. However, significant
mountain plover use of crop fields in Mexico has not been reported
(Macias-Duarte and Punjabi 2010, p. 7).
Wunder (2007) studied geographic population structure in mountain
plover through color-banding and stable isotope concentrations in
feathers. He concluded that there is widespread mixing of mountain
plover populations in winter and that birds may use alternate wintering
sites in different years (Wunder 2007, p. 118). While mountain plover
appear annually at some favored wintering sites, site fidelity by
individual birds appears low. Mountain plover can move long distances
and use various sites even within a given winter.
Survival, Lifespan, and Site Fidelity
A long-term study on mountain plover breeding grounds in Phillips
County, Montana, provides much of what is known regarding population
dynamics of the species. The annual survival rate of adult mountain
plover of both sexes in Phillips County ranged from 0.74 to 0.96 yearly
(Dinsmore 2008, p. 50). The annual survival rate for juvenile mountain
plover (survival to 1 year of age) was 0.06 at hatching, but for those
chicks that reached fledging age was 0.62 (Dinsmore 2008, p. 51).
Survival estimates did not account for permanent emigration (birds
surviving but returning in subsequent years to sites outside of the
study area), so the actual annual survival may have been higher.
Previous estimates of survival rates and of estimated mean lifespan
of 1.92 years (Dinsmore et al. 2003, pp. 1020-1021) supported our
December 5, 2002, conclusion that the mountain plover had a shorter
lifespan than other plovers (Charadriidae) (67 FR 72397) and that this
might impact its opportunity to reproduce. These conclusions
underestimated adult mountain plover survival. The longer study of the
same population over years with varying weather and habitat conditions
modified the earlier conclusions regarding the mountain plover's
longevity. Mountain plover of 5 to 7 years of age were frequently
encountered, and a longevity record over 10 years was established
(Dinsmore 2008, p. 52). Based on this additional research, survival
rates for mountain plover appear comparable to those reported for other
plovers, and the mountain plover is now considered a relatively long-
lived species (Dinsmore et al. 2010, unpaginated). We no longer believe
that the mountain plover's lifespan is a liability that could
contribute to the negative impact of natural or manmade events
affecting the species.
Mountain plover have a high nest survival rate compared to other
ground-nesting species (Dinsmore et al. 2010), but nest success in
mountain plover has varied greatly from study to study. Successful
hatching (of at least one egg) ranged from 26 percent (Knopf and
[[Page 27761]]
Rupert 1996, pp. 29-30) to 65 percent (Graul 1975, p. 18). Dinsmore et
al. (2002, pp. 3485-3486) found differences in nest success between
nests incubated by males (49 percent) and females (33 percent). Dreitz
and Knopf (2007, p. 684) found nest success of 37 percent with no
appreciable difference between nests on agricultural fields and on
native rangeland.
There have been relatively few studies of chick survival (hatching
to fledging) and results vary greatly. Dreitz (2009, p. 6) estimated
that 30-day survival of chicks of mountain plover from prairie dog
colony nesting habitat was 75 percent, and that 30-day survival on
other grasslands and on agricultural fields was less than 25 percent.
Following similar methodology, research on crop fields in Nebraska
found 95 percent survival of chicks accompanying 31 adult mountain
plover that were radio-tracked for the 36 days after eggs hatched
(Blakesley and Jorgensen 2010). Radio contact was lost with other
adults (due to birds leaving the area or transmitter failure), but even
if assuming all chicks associated with these adults perished, chick
survival was at least 58 percent (Blakesley and Jorgensen 2010). Dreitz
et al. (2010) studied post-hatching chick survival (hatching to
fledging) via radio-tracking in Colorado and Montana. The study
targeted factors affecting survival, including landscape
characteristics, with an objective of informing conservation and
management efforts. Field studies in 2010 were hampered by unusually
cold and wet weather. Of 93 chicks radio-tracked over three habitat
types in Colorado, only 9 were confirmed to survive to 30 days (Dreitz
et al. 2010, p. 3). Thirty-eight confirmed mortalities included 13 from
avian predators, 8 from mammalian predators, and 17 from unknown
predation, weather, and undetermined factors. Contact with other chicks
was lost, and their fates were unknown. Results did not reflect higher
chick survival on prairie dog towns than on other grasslands or
agricultural fields. In Montana, only 1 of 39 chicks monitored on
black-tailed prairie dog colonies was confirmed to survive to 30 days.
Nineteen mortalities were documented, with 13 from heavy rains (Dreitz
et al. 2010, p. 4). Sources of mortality differed among habitats in
Colorado, with avian predation higher at black-tailed prairie dog towns
(Dreitz et al. 2010, p. 6). However, results of the study are
considered preliminary, and future work is planned.
Few studies have estimated seasonal adult survival rates. Dreitz
(2010, unpaginated) found 89 percent survival of adults with broods for
the 30 days after hatching. A study of overwintering mountain plover in
California showed nearly 95 percent survival of wintering birds from
November 1 to March 15 (Knopf and Rupert 1995, p. 746). Since survival
of adults during stationary periods is believed to be relatively high,
and there is no estimate for adult survival during spring and fall
migration, there is potential that losses of adults during migration
may be significant and efforts to increase adult survival might be
focused on migration periods (Dinsmore et al. 2003, p. 1023; Andres and
Stone 2009, p. 1; Dinsmore et al. 2010). However, there is no
scientific information available to indicate that high mortality during
migration is occurring.
A life stage-specific model based on data from three breeding
areas, two in Colorado and one in Montana, found that mean adult
survival was the parameter that most influenced modeled population
growth (Dinsmore et al. 2010). The importance of adult survival was
characterized as typical of long-lived bird species, for which repeated
reproductive attempts throughout life are less important to population
growth, as evidenced by low chick survival, than adult survival
(Dinsmore et al. 2010). Nest survival was comparable to, or higher
than, other ground-nesting shorebirds and was less important to
population growth than survival of chicks, juveniles, and adults. Large
variation in estimates of chick survival led to the conclusion that to
improve population viability on breeding areas, management to increase
chick survival should be a priority. The authors believed such
management should be emphasized over past efforts to decrease nest
losses and increase hatching success (Dinsmore et al. 2010). However,
the authors conceded that management to improve chick survival is more
difficult than improving hatching success and might require large-scale
habitat improvement.
Mountain plover were thought to have high site fidelity to nesting
locations, returning to same area where they hatched each year (Graul
1973, p. 71). Skrade and Dinsmore (2010, p. 672) quantified mountain
plover dispersal on breeding sites in Montana and reported juvenile
(natal) dispersal (hatching year to return at age 1) averaged 8.1 mi
(13.0 km) for males and 6.3 mi (10.2 km) for females. Only 4 of 38
banded chicks returning as adults arrived back at the same black-tailed
prairie dog colony where they were banded. Knopf and Wunder (2006)
noted a chick that had dispersed over 30 mi (50 km) in Colorado.
The previous year's nesting success influences adult dispersal;
unsuccessful adults disperse farther than successfully breeding adults
(Skrade and Dinsmore 2010, p. 671). While adults rarely move far from
the area where they nested the previous year, evidence of potential for
year-to-year dispersal in adults is exemplified by an adult mountain
plover banded on a breeding area in Colorado in 2009, that was found
nesting approximately 25 mi (40 km) away in Nebraska in 2010 (Bly
2010b, pers. comm.).
Results from genetic studies suggest that gene flow among breeding
areas is sufficient to offset genetic effects of small populations and
reported adult fidelity to breeding areas (Oyler-McCance et al. 2008,
pp. 496-497).
Population Size and Trends
Mountain plover are difficult to detect because they are
cryptically colored and in general are widely distributed at low
densities (Knopf and Wunder 2006). Based on historical observations of
mountain plover and extensive habitat changes, there is general
agreement that the mountain plover is currently greatly reduced in
numbers and range compared to their numbers and range prior to European
settlement (Graul and Webster 1976, p. 265; Knopf and Wunder 2006). The
mountain plover's historical breeding range is believed to have
differed from that currently occupied primarily in its eastern extent,
which may have encompassed the western thirds of North Dakota, South
Dakota, and Nebraska, and more of western Kansas and the Texas
Panhandle than is currently occupied (Graul and Webster 1976, p. 265,
Knopf and Wunder 2008).
Population estimates for the species, both historical and recent,
appear imprecise. Graul and Webster (1976, p. 266) estimated that
mountain plover populations in Montana, Wyoming, eastern Colorado, and
New Mexico then totaled 214,200 to 319,220 birds, with 20,820 in the
population stronghold of Weld County, Colorado. However, Knopf and
Wunder (2008) cited Graul (pers. comm.) as saying that the estimates
may have been off (i.e., high) by an order of magnitude (a factor of
10).
Knopf (1996, p. 12) estimated the total population of mountain
plover to be about 8,000 to 10,000, based on a 1994 wintering survey in
California and on assumptions regarding proportion of the wintering
population observed (i.e., that only half of birds wintering in
California had been counted and that 1,000 to 3,000 birds wintered in
Texas and other areas). We cited this estimate in our
[[Page 27762]]
December 5, 2002, proposed rule (67 FR 72396). In our September 9,
2003, withdrawal of our proposed listing (68 FR 53083), we again cited
the Knopf estimate above and, using similar assumptions and newer
California winter survey data (1998-2002), provided a rangewide
estimate of 5,000 to 11,000 mountain plover. More recent studies, which
estimated populations present on specific portions of the breeding
range, have resulted in a higher rangewide estimate of the mountain
plover breeding population. After investigating Wyoming populations,
Plumb et al. (2005b, p. 15) estimated a minimum of 3,393 mountain
plover in Wyoming (up from previous estimates of 500 to 1,500) and
estimated a rangewide total of 11,000 to 14,000 mountain plover. Based
on newer information, including an upward revision of estimated
mountain plover numbers on the eastern Colorado plains (a conservative
estimate of 8,577 birds), Tipton et al. (2009, p. 497) provided a
rangewide estimate of 15,000 to 20,000 mountain plover. Andres and
Stone (2009, p. 8) reviewed available data and provided a coarse,
minimum rangewide estimate of 18,000 breeding mountain plover. Knopf
and Dreitz (in press) concluded that the continental breeding
population is ``certainly larger'' than the 17,500 birds estimated in
Montana, Wyoming, and Colorado, citing small populations in contiguous
States, a potentially significant population in New Mexico, and an
unknown population in Mexico. Based on our review of recent data,
including those from Nebraska (Van der Berg et al. 2010) and New Mexico
(see Breeding Range below), we estimate that the current rangewide
mountain plover breeding population exceeds 20,000 birds. This was
supported by Knopf (2009, pers. comm.). We have no information to
indicate that this estimate reflects an actual increase in rangewide
mountain plover numbers over previous, lower estimates. Instead, it
likely reflects the limitations of those earlier rangewide estimates
(based on mountain plover wintering in California that largely
discounted birds wintering elsewhere) and more accurate recent
estimates of breeding populations.
Accurate trend information for mountain plover numbers is generally
lacking. Interpreting trends from the two long standing surveys, the
Breeding Bird Survey (BBS) and the National Audubon Society's Christmas
Bird Count (CBC), suffer from a variety of problems, including the
inherent difficulties associated with using a survey of only a small
portion of a total population to infer rangewide trends (Knopf and
Wunder 2004, p. 1).
The BBS is a large-scale survey of North American birds that began
in 1966, and is conducted during the breeding season by observers
driving along roads over established routes. Knopf (1996, p. 12) cited
BBS data from 1966 through 1993 as indicative of a steep decline in
mountain plover numbers across their breeding range (3.7 percent per
year, a decline of approximately two-thirds over the period). However,
Knopf and Wunder (2004, p. 1) suggested that the timing of surveys
(which occur mostly in June when mountain plover are less conspicuous)
and the low densities at which mountain plover occur prevent reliable
trend estimates.
Based on recent BBS data analysis (Sauer 2010a), the mountain
plover has declined rangewide at an estimated rate of 2.6 percent per
year for the period from 1966 to 2009 (95 percent confidence interval
(CI) -6.7 to +0.6). However, for the period from 1999 through 2009, the
estimated rate of decline decreased to 1.1 percent per year (95 percent
CI -5.8, +9.6) (Figure 2). While neither estimate varies statistically
from a stable population (at a 95 percent CI), the probability that the
estimated long-term trend (1966 through 2009) is less than or equal to
zero is 95 percent. The probability that the estimated short-term trend
(1999 through 2009) is less than or equal to zero is 68 percent. The
estimated long-term decline is consistent with the generally accepted
conclusion that the mountain plover's rangewide population is currently
smaller than it was in the 1960s. The more recent (1999 through 2009)
estimated decline and associated CI lead us to conclude that most or
all of the long-term decrease took place before 1999, that any recent
declines are modest, and that the mountain plover population may be
near stable.
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[GRAPHIC] [TIFF OMITTED] TP12MY11.001
Sauer (2011, pers. comm.) concluded that limited regional data from
the BBS (i.e., the low numbers of routes reporting the species and low
numbers of mountain plover observed) resulted in imprecise trend
estimates within individual States and for the time periods of
interest. He also concluded that BBS data only provide an imprecise
summary of mountain plover population dynamics, and the limited sample
size likely reflects the limitations of the roadside sampling frame in
sampling mountain plover breeding populations.
We conclude that, while the BBS is the only long-term trend
information available for the mountain plover on its breeding range, it
is an imprecise indicator of mountain plover population trends. Given
the wide confidence interval and the conclusion by Sauer (2011, pers.
comm.) above, the data provide limited support for any recent (1999
through 2009) trend in mountain plover numbers. Even so, we acknowledge
that this is the best available information on trends for this species
and BBS survey results suggest a recent (1999 through 2009) moderated
rate of decline (Figure 2). We provide long-term and recent BBS trend
estimates for three States where the sample size allowed for analysis
(see Conservation Status and Local Populations below), but with the
same reservations regarding precision.
The CBC is an annual count performed around the end of December in
which volunteers observe birds in 15-mi (24-km) radius count circles.
While CBCs can be used to infer species population trends, spatial
coverage is limited (Knopf and Wunder 2004, p. 1) and established count
circles commonly coincide with populated areas where volunteers are
available. The CBC data estimated an annual decrease of 2.8 percent in
mountain plover observed from 1966 through 2007, but reliability was
described as low (Butcher and Niven 2007, Appendix 1).
The vast majority of mountain plover reported in CBCs come from
California and, within California, from the South Salton Sea count.
Pandolfino (2009, unpaginated) submitted his analysis of CBC data for
California and recognized the data's limitations, but concluded that
the data reflected long-term and recent declines in mountain plover
numbers wintering in California. The CBC data on mountain plover
numbers is highly variable from year to year. The Salton Sea South CBC,
the only CBC in the Imperial Valley, is limited in scope and does not
include portions of the valley where most mountain plover have been
seen (Wunder and Knopf 2003, p. 76). Inherent limitations in data
collection methods (volunteers surveying small areas relative to total
winter range) and lack of sufficient detections of mountain plover in
California count circles (Hunting et al. 2001, p. 40) render trend
analysis uncertain. CBC data from other States and Mexico is even less
representative
[[Page 27764]]
of wintering populations and provides no insight into possible trends
for the mountain plover.
We conclude, based on observations across the mountain plover's
range and BBS trend data, that a historical decline of the mountain
plover has occurred since the 1960s. However, we agree with the
conclusion of Andres and Stone (2009, p. 3) that precise and accurate
information on recent trends in mountain plover numbers is lacking. The
recent (1999 through 2009) decline estimate from BBS data is modest
(1.1 percent per year) and any difference from a stable population
estimate (slope of 0.0) is statistically insignificant. However, we
acknowledge that the BBS data is the best available information on
trends for the mountain plover and that BBS results suggest a recent
(1999 through 2009) moderated rate of decline (Figure 2). The CBC
wintering data are highly variable and come mostly from California, but
also suggest a long-term decline. No comprehensive trend data across
the mountain plover's wintering range are available. The discussion
below provides information on populations and trends within States,
Canada, and Mexico, where available.
Conservation Status and Local Populations
The mountain plover is listed as endangered in Canada, as a
sensitive species in Alberta, and as a threatened species in Mexico
(Andres and Stone 2009, p. 13; Gober 2010). The mountain plover is
identified by the Service as a Bird of Conservation Concern (Service
2008), is considered ``highly imperiled'' in the U.S. Shorebird
Conservation Plan (2004, p. 2), a category assigned to species listed
as threatened or endangered nationally, and all species with
significant population declines and either low populations or some
other high risk factor. It is also identified as ``G3-vulnerable'' by
NatureServe (2010). The species is listed as a sensitive species by the
U.S. Forest Service (USFS) (2010) and by the Bureau of Land Management
(BLM) (2000a, 2006, 2010a). It is identified as a species of global
conservation concern in the American Bird Conservancy and National
Audubon Watchlist, and it is listed as ``near threatened'' by the
International Union for the Conservation of Nature (IUCN) (BirdLife
International 2010). The designations discussed above may, in part,
reflect population estimates at the time those designations were
established. The IUCN previously (from 2004 to 2007) listed the species
as ``vulnerable,'' a higher level of concern than ``near threatened,''
but changed its rating as higher rangewide population estimates
emerged. The U.S. Shorebird Conservation Plan provided a rangewide
estimate of 9,000 mountain plover until 2006, when the estimate was
revised upward to 12,500 (Morrison et al. 2006, p. 69).
All States within the range of the mountain plover have included
the species in their Comprehensive Wildlife Conservation Strategy or
Wildlife Action Plans or both (State Plans) (Arizona Game and Fish
Department 2006; University of California 2005; Colorado Division of
Wildlife 2006; Wasson et al. 2005; Montana Fish, Wildlife and Parks
2005; Schneider et al. 2005; New Mexico Department of Game and Fish
2006; Oklahoma Department of Wildlife Conservation 2005; Texas Parks
and Wildlife 2005; Wyoming Game and Fish Department 2005) as either
``Species of concern'' or ``Species of greatest conservation need.''
Each State categorizes species under these designations based on
available information about the status, distribution, and trend of the
species in their State. They are not regulatory classifications, but
rather are intended to guide resource managers in making proactive
decisions regarding species conservation and data collection
priorities. The State Plans are not intended to be specific action
plans for any species. These designations do not result in any
protection for the species. However, the mountain plover is identified
as threatened in the State of Nebraska, the only State where the
species is listed as endangered or threatened.
Breeding Range
Colorado
In Eastern Colorado, the shortgrass prairie ecosystem provides
flat, dry breeding habitat for the mountain plover. The species
occupies grasslands within prairie dog colonies, grasslands without
prairie dog colonies, and dry land agricultural fields (Dreitz et al.
2005, pp. 129-130; Tipton et al. 2009, p. 496).
Knopf and Miller (1994, p. 504) noted the PNG, Weld County,
Colorado, as a breeding stronghold for the species, but in the mid-
1990s the population fell dramatically. The PNG now supports relatively
few breeding mountain plover. In 2009, Knopf provided an overview of
mountain plover studies on the PNG from 1986 through 2007. He suggested
that mountain plover numbers on the PNG had been in decline since the
late 1930s and early 1940s, and that the dramatic decline in the mid-
1990s was the abrupt endpoint of a process of deteriorating habitat,
exacerbated by other factors such as wet spring weather, increased
predation, and the relocation of breeding mountain plover to better
habitats elsewhere (Knopf 2008, p. 61).
Despite the virtual loss of the PNG population, over half of all
mountain plover are thought to breed in Colorado (Andres and Stone
2009, p. 15). A recent study reported a conservative estimate of 8,577
breeding mountain plover in eastern Colorado (95 percent CI 7,511 to
35,130) (Tipton et al. 2009, p. 497). A separate, higher elevation
population in South Park, Park County, Colorado, was estimated at 2,310
adults (Wunder et al. 2003, p. 661). Surveys through 2006 suggested a
stable population in South Park, with any variation largely
attributable to wet years and dry years affecting breeding conditions
(Wunder 2010a). Small numbers of mountain plover also occur in
Colorado's San Luis Valley (Hicks-Anderson and VerCauteren 2006,
entire). Andres and Stone (2009, p. 8) provided population estimates
for the United States, Canadian provinces, and Mexican States based on
their review of all available information. Their estimate of 11,000
mountain plover breeding in Colorado appears appropriate given
information available.
The BBS data from Colorado, 1966 through 2009 (-0.9 percent decline
annually, 95 percent CI (-7.0 to 3.5)) and 1999 through 2009 (0.3
percent increase annually, 95 percent CI (-5.5 to 14.7)) (Sauer 2010a),
suggest little long-term or recent change in breeding numbers in
Colorado. Based on these data, we conclude that the current breeding
population in Colorado, which likely supports half or more of all
breeding mountain plover, is relatively stable.
Wyoming
Wyoming has the highest estimated number of breeding mountain
plover outside of Colorado. The mountain plover is locally common and
has been detected in every county of Wyoming (Smith and Keinath 2004,
p. 3). A projected 20.5 million ac (8.3 million ha) of mountain plover
habitat exists in Wyoming, with 59 percent occurring on public lands
(Wyoming Natural Diversity Database (WYNDD) 2010; Emmerich 2010).
Nesting of mountain plover in Wyoming occurs in both grassland,
mostly in the eastern part of the State, and desert-shrub (Plumb et al.
2005b, p. 20). Mountain plover densities were comparable across habitat
types with overall density only slightly higher in grassland than in
desert-shrub (Plumb et
[[Page 27765]]
al. 2005b, p. 20). Mountain plover appear to have less association with
prairie dog habitat in Wyoming than elsewhere (Plumb et al. 2005a, p.
226). Little of the mountain plover breeding range in Wyoming
(approximately 12 percent) is on cropland Knopf and Rupert 1999, p.
85).
Plumb et al. (2005b, pp. 19-20) estimated a minimum population of
3,393 mountain plover in Wyoming in 2002 and 2003. Andres and Stone
(2009, p. 8) provide an estimate of 3,400 mountain plover breeding in
Wyoming. This number is based on Plumb et al.'s estimate and, like that
estimate, it reflects the minimum number likely present. Given that
Plumb et al. (2005b, pp. 19-20) provided a conservative estimate, the
actual breeding population is likely larger; however, we have no basis
to provide a more accurate estimate.
The BBS data from Wyoming (Sauer 2010a), 1966 through 2009 (-1.2
percent decline annually, 95 percent CI (-5.7 to 3.3)) and 1999 through
2009 (-2.3 percent decline annually, 95 percent CI -13.9 to 4.5)),
suggest that both long-term and recent declines in breeding mountain
plover numbers in Wyoming may have occurred.
Montana
Primary breeding habitat for mountain plover in Montana is in the
north-central portion of the State where mountain plover are highly
dependent on black-tailed prairie dog colonies for habitat. Montana
Fish, Wildlife and Parks modeled suitable mountain plover habitat in
the State. Mapping indicated that the greatest area of highly suitable
habitat occurs in Phillips, Blain, Valley, and Fergus Counties with
patchy distribution though the central and southeast portions of the
State. The total area of suitable habitat estimated was 18.5 million ac
(7.5 million ha) (McDonald 2010).
Childers and Dinsmore (2008, p. 706) reported an estimate of 1,028
mountain plover in Phillips and Valley Counties in 2004 (95 percent CI
(903 to 1,153)). In 2010, standardized census areas in southwest,
central, and northeast Montana produced fewer sightings than previous
surveys (1992-2000, 2004); however, McDonald (2010) stated that results
were negatively influenced by above average rainfall, increased
vegetation height, and limited private land access; therefore, results
cannot be relied upon. Other than apparent confirmation of a previously
documented decline in the southwest census area (FaunaWest Wildlife
Consultants 2004, pp. 4-5), no trends could be inferred from the 2010
survey.
Andres and Stone (2009, p. 8) used the above estimate by Childers
and Dinsmore (2008, p. 706) and previous estimates of about 600
mountain plover elsewhere in Montana and provided a Statewide estimate
of approximately 1,600 mountain plover. BBS observations of mountain
plover on routes in Montana were insufficient to provide estimates of
population trend.
New Mexico
Most breeding season reports of mountain plover in New Mexico have
come from the northeast and western counties. Sager (1996, pp. 8-9)
found 152 presumed breeding adults at 35 sites in 11 counties in
northern New Mexico. Marguilies et al. (2004, p. 3) estimated 200
mountain plover in Union County alone throughout the summer and located
46 nests. In a limited effort, they also found 22 mountain plover and
six nests on public lands in Taos and Colfax Counties.
At BLM's North Unit, Taos County, point counts in 2005 through 2007
estimated 176 mountain plover on 8,400 ac (3,400 ha) of the 50,000-ac
(20,000-ha) unit considered to be favorable mountain plover breeding
habitat, based on past observation of mountain plover (Hawks Aloft
2007, pp. 9-11). If the entire unit was occupied at the same density,
an estimated 1,000 mountain plover might have been present on the North
Unit. Manderson (2010, pers. comm.) inspected habitat away from survey
routes in 2010, and suggested that, based on habitat quality, 500 or
more mountain plover could be present on the entire unit. Mountain
plover numbers seen on the same survey routes in 2010 were comparable
to those in earlier (2005 through 2007) surveys (Hawks Aloft 2010, p.
13), suggesting this population may be stable.
Goguen (2010, pers. comm.) estimated a minimum of 40 to 50 breeding
mountain plover on the Vermejo Ranch, Colfax and Taos Counties.
Mountain plover were also recently reported present in El Malpais
National Conservation Area, Cibola County (Hawks Aloft 2008, entire).
We found no Statewide breeding surveys or estimates of Statewide
breeding populations for mountain plover in New Mexico, other than
Andres and Stone's (2009, p. 8) conservative estimate of 500. Given the
above data from Union County, the BLM's North Unit in Taos County, the
Vermejo Ranch in Colfax and Taos Counties, and likely mountain plover
occurrence in several other counties, we believe that at least 1,000
and potentially significantly more mountain plover breed in New Mexico.
BBS data from New Mexico (Sauer 2010a), 1966 through 2009 (-5.0
percent decline annually, 95 percent CI (-8.6 to -1.2)) and 1999
through 2009 (-4.8 decline annually, 95 percent CI (-12.1 to 2.7)),
demonstrate a long-term decline and also suggest a short-term decline
in breeding mountain plover numbers in New Mexico. New Mexico is the
only State for which the long-term BBS trend statistically differs from
zero.
Nebraska
In our December 5, 2002, proposal to list the mountain plover we
estimated 200 mountain plover in Nebraska (67 FR 72399). Recent studies
attempted to identify the extent of breeding distribution and
population size in Nebraska (Bly et al. 2008, entire). Most nests were
found on agricultural fields in Kimball County, in extreme southwestern
Nebraska, but mountain plover were also found in nearby Cheyenne and
Blain Counties. The minimum breeding population was estimated to be 80
adults in 2007, based on nests found, and the total estimate of
breeding birds ranged upward to 360 (Bly et al. 2008, p. 127). Van der
Burg et al. (2010, pp. 50-53) reported on monitoring in the same three
counties (Kimball, Cheyenne, and Blain) in southwestern Nebraska and
estimated that mountain plover breeding numbers of 1,650, 1,617, and
1,558 over 3 years of the study (2005, 2006, and 2007, respectively).
The authors attributed past low estimates in Nebraska to: (1) Low
detection probabilities; (2) clumped spatial distribution of mountain
plover, which their estimation methodology corrected for; and (3)
``chronic undersampling.'' Given the above estimates from Van der Burg
et al. (2010, pp. 50-53), an estimate by Andres and Stone (2009, p. 8)
of 500 breeding mountain plover in Nebraska appears low.
Nebraska is the only State that has regulatory mechanisms in place
to conserve the mountain plover and its habitat, which likely protect
relatively few individuals. The Nebraska Game and Parks Commission
lists the mountain plover as a ``threatened'' species. Listing of
endangered and threatened species identifies those animals and plants
whose continued existence in Nebraska is in jeopardy. Efforts can then
be made to restore the species or to prevent extirpation or extinction.
Once a species is listed, a State law, titled the Nebraska Nongame and
Endangered Species Conservation Act, automatically prohibits take,
exportation, and possession, and imposes severe penalties on violators
(Nebraska Game and Parks Commission
[[Page 27766]]
2011). Proposed projects that would be authorized, funded, or carried
out by Nebraska State agencies are reviewed as part of a mandatory
consultation process designed to prevent a State action from
jeopardizing the existence of an endangered or threatened species.
Recovery plans for endangered or threatened species are developed;
these recovery plans identify, describe, and schedule the actions
necessary to restore populations of these animals and plants to a more
secure status. Given that most mountain plover in Nebraska occur on
private agricultural lands, there are not many State projects that are
reviewed under the law. It is generally implemented only 4 or 5 times
per year, primarily on transportation, transmission, and energy
development projects (Lackey 2011, pers. comm.). While this law may
provide protection for some individual mountain plover in Nebraska, we
believe that it would only have minimal positive effects on the entire
population in Nebraska, or on the rangewide population.
Oklahoma
Recent studies to determine the breeding distribution and
population size in Oklahoma detected mountain plover in Cimarron and
Texas Counties in the Oklahoma panhandle, mostly on fallow or barren
agricultural fields (McConnell et al. 2009, pp. 30-33). Randomized
point counts were used to derive a Statewide population estimate of 68
to 91 birds (McConnell et al. 2009, pp. 32-33). Andres and Stone (2009,
p. 8) estimated 200 mountain plover breeding in Oklahoma. Given results
of McConnell et al. (2009, pp. 32-33), we believe that Andres and
Stone's (2009, p. 8) estimate may be slightly high. The range of the
mountain plover in Oklahoma was described as stable over the past 100
years, with the suggestion that populations may have changed little
(Hatcher 2010).
Kansas
The Kansas Department of Wildlife and Parks (2005) stated that
mountain plover breed only on dry upland in the shortgrass prairie of
western Kansas. While conversion to agriculture has left little native
breeding habitat, Cable and Seltman (2010, pp. 50-51) reported mountain
plover are an uncommon but regular breeding species in western Kansas
and that they also use idle cropland. Morton County may also serve as a
staging area for migration in late summer (Cable and Seltman 2010, p.
51). Andres and Stone (2009, p. 8) estimated 200 breeding mountain
plover in Kansas. No comprehensive surveys of breeding mountain plover
in Kansas have been attempted; however, given their apparent use of
both prairie and cropland, and a substantial population in nearby
Colorado, the estimate may be appropriate.
Texas
The mountain plover likely breeds in Texas, but there are no
confirmed reports of breeding since 1993 (Andres and Stone 2009, p.
16). Holliday (2010) described breeding season sight reports of
mountain plover from the Texas Panhandle near known Oklahoma breeding
sites. Holliday (2004) also mapped potential breeding habitat, much of
it on private land that has not been surveyed. Andres and Stone (2010)
did not provide an estimate of breeding mountain plover in Texas. We
believe that at least minimal numbers of mountain plover breed in
Texas.
Arizona
The only known mountain plover nesting in Arizona is in Apache
County in east-central portion of the State, with at maximum perhaps a
dozen breeding birds (Gardner 2010, pers. comm.). Breeding has occurred
on grasslands where cattle were concentrated and at Gunnison prairie
dog (C. gunnisoni) colonies (Corman 2005, pp. 591-591; Gardner 2010).
However, hundreds of square miles of potential breeding habitat in
northern and western Arizona have never been surveyed, and there are
reports of potential breeding mountain plover on Tribal lands in Navajo
County (Corman 2005, pp. 591-591; Gardner 2010, pers. comm.). Andres
and Stone (2009, p. 8) estimated 100 breeding mountain plover in
Arizona. This estimate acknowledges potential for a more substantial
breeding population than limited observations have documented.
Utah
The mountain plover has been a historically rare breeder in shrub-
steppe habitat in the Uinta Basin of northeastern Utah. Manning and
White (2001, p. 225) described a small breeding population that
averaged about 15 adults yearly. Mountain plover breeding in the area
subsequently declined, and no birds have been found during surveys of
the area since 2003 (Maxfield 2010, pers. comm.). Andres and Stone
(2009, p. 8) estimated fewer than 50 breeding mountain plover in Utah.
Based on no recent records of breeding mountain plover, this estimate
may be optimistic.
North Dakota and South Dakota
The mountain plover once bred in these States, with higher numbers
present in South Dakota, but there are no recent breeding records in
either North Dakota or South Dakota (North Dakota Game and Fish
Department 2010; South Dakota Game, Fish and Parks 2010).
Canada
A review of breeding records for Canada (Knapton et al. 2006, p.
33) concluded that the mountain plover is a peripheral species in
Canada with no evidence that it was ever a common or regular breeder.
The first breeding record was documented in 1979 and the most recent in
2007 (Knapton et al. 2006, pp. 32-33; Holroyd 2010, pers. comm.). Most
sightings and breeding records come from extreme southeastern Alberta,
with at least one incidence of confirmed breeding in Saskatchewan.
Holroyd (2010, pers. comm.) provided updated records of sightings
through 2009, mostly from Alberta. Andres and Stone (2009, p. 8)
estimated fewer than 100 mountain plover breeding in Canada. We are not
aware of any attempts to systematically survey all potential breeding
areas in the Canadian range. However, given the low number and limited
distribution of reported recent sightings (Holroyd 2010, pers. comm.),
we believe that actual breeding numbers are fewer than 100.
Mexico
Breeding records of mountain plover in Mexico have been documented
in southeastern Coahuila and Nuevo Leon, following a history of
breeding season observations in Mexican prairie dog colonies (Desmond
and Chavez-Ramirez 2002 entire; Gonzalez-Rojas 2006, pp. 81-84).
Nesting is suspected in San Luis Potosi, 130 mi (200 km) south of the
above records (Luevano et al. 2010, p. 123).
The extent of mountain plover breeding in Mexico is largely
unknown. Andres and Stone (2009, pp. 8, 15) estimated fewer than 300
mountain plover breeding in Mexico (fewer than: 50 in Chihuahua, 100 in
Cohuila, 100 in Nuevo Leon, and 50 in San Luis Potosi), but suspect
that if there are major concentrations of breeding mountain plover not
yet discovered anywhere in their range, they are likely in Mexico. The
estimate of fewer than 300 birds is at best a guess, but is
appropriately conservative given the lack of knowledge regarding
breeding mountain plover occurrence and distribution in Mexico.
In summary, we believe that the rangewide breeding population of
mountain plover likely exceeds 20,000, with largest populations in
Colorado, conservatively 11,000; Wyoming,
[[Page 27767]]
conservatively 3,400; Montana 1,600; Nebraska 1,600; New Mexico, at
least 1,000 and potentially many more; and smaller populations
elsewhere (Kansas, Oklahoma, Texas, Utah, Canada, and Mexico).
Wintering Range
California
Mountain plover are found from north-central California to the
Mexico border, mostly from September to mid-March, with peak numbers
from December through February (Knopf and Wunder 2006; Hunting and
Edson 2008, p. 181). Mountain plover were historically common on the
coastal plain in southern California (coastal prairie, alkaline flats,
agricultural fields) before being displaced by human development
(Hunting and Edson 2008, p. 182; Wunder and Knopf 2003, p. 78).
Historically, much of the mountain plover habitat in the Central Valley
grasslands was lost following the decline of grazing elk (Cervus
canadensis), pronghorn antelope, burrowing kangaroo rats, ground
squirrels (Spermophilus spp.), and other mammals. The combined
activities of these herbivores maintained suitable habitat conditions
for mountain plover, conditions closely resembling habitat
characteristics found on breeding habitats (Knopf and Rupert 1995, p.
750). Farther south in California, desert scrub in the Imperial Valley
was converted to agriculture beginning in the 1940s, creating important
wintering habitat for the mountain plover. See Hunting and Edson (2008,
p. 181) for details of the mountain plover's historical range and
abundance in California.
Mountain plover currently occur in the greatest numbers in two
general areas in California: (1) The western Central Valley from
southern Colusa and Yolo Counties in the north to Kern County in the
south (especially the western San Joaquin Valley, the name by which the
southern Central Valley is known); and (2) the Imperial Valley in
Imperial County (Hunting and Edson 2008, p. 182). The Carrizo Plain,
separated from the San Joaquin Valley by the Temblor Range, and the
Panoche Valley are also regularly occupied wintering areas.
Populations and trends in the Central Valley are difficult to
determine due to the abundance of potential habitat, flock movements,
and lack of systematic surveys (Knopf and Rupert 1995, p. 749; Edson
and Hunting 1999, p. 17). In our December 5, 2002, proposal to list the
mountain plover (67 FR 72396), we included Edson and Hunting's 1999 (p.
27) comment that mountain plover were ``rare and local, exceedingly
rare, or accidental'' within individual counties in the San Joaquin
Valley. Wunder and Knopf (2003, p. 78) suggested that, as a result of
habitat loss, many mountain plover had shifted from the Central Valley
to the Imperial Valley. Hunting and Edson (2008, p. 182) considered
reports of 200 to 300 birds in the San Joaquin Valley in winter of
2004-2005, 100 to 200 in Madera County in 2005-2006, 645 in Tulare
County in December 2005, and about 300 in western Kings County in
January 2006 to be ``exceptional.'' They also found noteworthy a survey
total of 381 mountain plover at the Carrizo Plain in 2006 (Hunting and
Edson 2008, p. 182). However, recent reports from the Central Valley
also include 645 birds in Madera County in 2006 (McCaski and Garrett
2006, p. 283), 426 in Tulare County in 2007 (McCaski and Garrett 2007,
p. 326), 230 in San Joaquin County in 2008 (eBird 2010), 230 in Solano
County in 2008 (Central Valley Bird Club 2010), and 223 in Kern County
in 2010 (eBird 2010). These reports suggest that significant numbers of
mountain plover continue to use widespread areas of the Central Valley
annually. Nearby, a recent high count for the Carrizo Plain National
Monument was 540 birds in 2009 (Sharum 2010).
In the Imperial Valley, coordinated surveys by 26 observers over 2
days in December 1999 sighted 3,758 mountain plover (Shuford et al.
2004, p. 7). A survey of mountain plover and their use of cultivated
fields in the Imperial Valley of California in 2001 found 4,037 birds
(Wunder and Knopf 2003, p. 75), and 3,476 were counted from January 29
through February 6, 2002, by four observers, with the largest flock
consisting of 410 birds (AMEC Earth and Environment 2003, p. 9-10).
Mountain plover wintering in the Imperial Valley were surveyed in 2003
and 2004, in an attempt to develop a statistically reliable estimate of
numbers (Knopf and Wunder 2004, entire). Flocking behavior, mobility,
and weather were among factors found to limit the reliability of
Imperial Valley estimates (Knopf and Wunder 2004, pp. 9-12). Results of
more recent survey estimates in the Imperial Valley include more than
4,500 mountain plover seen in January 2007, approximately 3,000 seen in
January 2008, and 827 seen in January 2011 (Kelsey 2011, pers. comm.).
Hunting et al. (2001 p. 40), Wunder and Knopf (2003, p. 76), and
Hunting and Edson (2008, pp. 181-183) all suggested a significant
decline in numbers of mountain plover wintering in California over
previous decades. However, we found little evidence available to
establish any trend in more recent (2000 to present) wintering numbers
in California. The 4,500 mountain plover recorded in the Imperial
Valley survey in 2007 (Kelsey 2011, pers. comm.) exceeded mountain
plover observed in Statewide surveys from 1994, and 1998 through 2002
(Knopf 1996, p. 12; 68 FR 53083). Most recently, a Statewide survey
over 5 days in January 2011 found 1,235 mountain plover (Kelsey 2011,
pers. comm.), considerably fewer than found in previous Statewide
surveys or recent Imperial Valley surveys. However, it is not apparent
how unusually wet weather or other factors contributed to the
relatively low number of mountain plover reported in the 2011 survey.
California experienced heavy rains in late 2010. December 2010 was the
City of Los Angeles' wettest December in 121 years (Southern California
Weather Notes 2010).
While California remains the best documented wintering area for the
mountain plover, it may winter less than 50 percent of the estimated
breeding population (Andres and Stone, p. 9). Knopf (1996, p. 12)
estimated 7,000 mountain plover wintering in California and 1,000 to
3,000 wintering elsewhere. In our December 5, 2002, proposed rule to
list the mountain plover as threatened, we suggested that few mountain
plover wintered in Texas, Arizona, and Mexico (67 FR 72397). We do not
know the actual number of mountain plover wintering in California or
how the number varies from year to year; however, given no recent
evidence that wintering birds in California number more than the 7,000
estimate above (Knopf 1996, p. 12), and our current rangewide estimate
of at least 20,000 breeding mountain plover, the previous contention
that California winters the majority of all mountain plover appears
incorrect. The fewer mountain plover that are wintering in California,
on average or in any given winter, the more important that wintering
areas outside California become. Unfortunately, we have little
information to pinpoint where the majority of mountain plover are
wintering.
Texas
Holiday (2010), based on an examination of LandSat (satellite)
photos, found that winter records of mountain plover in Texas
correlated to the distribution of barren fields and grazed pastures. He
also suggested that the northern limit of the wintering range
[[Page 27768]]
in Texas is related to the average number of frost-free days, which
influences insect availability. Collins (2006, pp. 27-31) summarized
mountain plover wintering status in Texas (with much of the compiled
records and maps attributable to Holliday). Populations in Hondo County
and Medina County areas were described as potentially the largest;
Williamson County was characterized as a well-known wintering area, but
with populations potentially small compared to other less known areas.
Mountain plover were also present around Wharton, Wharton County, and
surrounding counties, and the Corpus Christi area was said to
potentially hold more mountain plover than reports indicate (Collins
2006, p. 30). Estimates by knowledgeable local birders of wintering
mountain plover in the coastal bend area (Nueces and San Patricio
Counties) ranged from 200 up to 2,000 to 3,000 birds (Cobb 2009, pers.
comm.). The higher numbers were characterized as speculative because
the vast amount of available habitat where access is generally limited
makes it difficult to draw any conclusions. Andres and Stone (2009, p.
20) provided an estimate of 1,500 mountain plover wintering in Texas,
with a note that abundance could be much greater.
Arizona
Approximately 500 mountain plover are believed to winter in
agricultural areas of southern and western Arizona, but numbers could
be higher because private and Tribal lands are largely unsurveyed
(Gardner 2010). Wintering numbers in La Paz and Pinal Counties appeared
stable; numbers in Cochise County have significantly decreased in the
last 10 to 15 years due to urban expansion; and Yuma County populations
were characterized as increasing, with 150 to 300 birds annually
(Gardner 2010; Robertson 2010, pp. 3-4). Wintering mountain plover are
also reported from the Sulphur Springs Valley in Cochise County
(Robertson 2010, p. 2). Andres and Stone (2009, p. 20) provided an
estimate of 200 mountain plover wintering in Arizona. Given limited
coverage of potential wintering habitat, we consider the above estimate
of 500 birds wintering in Arizona the likely minimum.
Nevada
Wintering mountain plover are rarely reported from Nevada, with the
most recent reports of up to 17 mountain plover coming from the
Armagosa Valley near the Nevada-California border northwest of Las
Vegas (eBird 2010).
New Mexico
While some mountain plover likely winter in southern New Mexico, we
have no information regarding locations or numbers.
Mexico
Mountain plover's winter distribution in Mexico has not been well
studied, but the species is believed to winter from along the United
States-Mexico border south into the border States of Baja California,
Sonora, Chihuahua, Coahuila, Nuevo Leon, and Tamaulipas, and beyond
into Durango, Zacatecas, and San Luis Potosi (Gonzales-Rojas et al.
2006, p. 81; Knopf and Wuder 2006; Macias-Duarte and Punjabi 2010, p.
4). While the Mexicali Valley, Baja California, located just south of
the Imperial Valley, seems to have suitable wintering habitat (200,000
ac (80,000 ha) of farmland), mountain plover have rarely been reported
from the area (Macias-Duarte and Punjabi 2010, p. 3).
Two primary concentration areas within the Chihuahuan Desert are
believed to be most important for wintering mountain plover: (1) The
Janos area in northwestern Chihuahua; and (2) the El Tokio grasslands
in southern Coahuila, Nuevo Leon, northeastern Zacatecas, and northern
San Luis Potosi (Macias-Duatre and Punjabi 2010, pp. 3-6). Mountain
plover are most abundant in the La Soledad region of the El Tokio
grasslands. The highest estimated density in Llano de la Soledad (based
on data from the winter of 2005-2006) extrapolated over the area
suggests that over 2,000 mountain plover were present. Extrapolation
from Llano de la Soledad to all prairie dog colonies in the entire El
Tokio region provided an estimate of 6,800 mountain plover (Macias-
Duarte and Punjabi 2010, p. 6). While this estimate is crude and may be
optimistically high, it is not inconsistent with reports of mountain
plover flocks in the area totaling 1,600 to 3,500 birds reported by
Andres and Stone (2009, p. 18). In the winter of 2005-2006, surveys in
Janos estimated 1,435 birds (Salinas 2006, p. 43).
The reported sightings and the estimates presented above are
maximums reported, and the numbers can vary greatly from year to year.
However, these reports suggest that a substantial number of mountain
plover may winter in Mexico. Andres and Stone (2009, p. 20) provided an
estimate of 5,000 birds wintering in Mexico. Changes in sampling
methodology, annual variability in mountain plover numbers, and the
short duration covered by recent systematic surveys prevent any
conclusions regarding trends (Macias-Duarte and Punjabi 2010, pp. 5-6,
16, 17).
Summary of Comments and Recommendations
We requested written comments from the public on the proposed
listing of the mountain plover during the June 29, 2010, through August
30, 2010, comment period that followed our June 29, 2010, document (75
FR 37353) vacating our September 9, 2003, withdrawal (68 FR 53083) and
reinstating our December 5, 2002, proposal to list the mountain plover
(67 FR 72396). We contacted appropriate Federal, State, and local
agencies; scientific organizations; and other interested parties, and
invited them to comment on the proposed rule and supporting documents.
Following an initial draft of our final determination we contacted 5
peer reviewers and asked them to review selected portions of the draft.
We received 53 comments in response to the December 5, 2002,
proposed rule (67 FR 72396) during the June 29, 2010, to August 30,
2010, comment period. These included comments from 3 Federal entities,
10 States, 3 local governments, 28 organizations or groups (business,
industry, environmental), and 8 private parties. WildEarth Guardians
also forwarded us 302 similar comments from individuals, and the
Colorado Farm Bureau forwarded us 8 similar comments from individuals.
We received no requests for public hearings. We also reviewed comments
received after our February 16, 1999, and December 5, 2002, proposals
to list the mountain plover (64 FR 7587 and 67 FR 72396, respectively)
for relevant issues not addressed in more recent comments. All
substantive comments have either been incorporated into this final
determination or are addressed below.
Peer Review
In accordance with our policy published in the Federal Register on
July 1, 1994 (59 FR 34270), we solicited expert opinions from five
knowledgeable individuals with scientific expertise that included
familiarity with the mountain plover, with other shorebird species, the
geographic region and habitats in which the mountain plover occurs, and
conservation biology principles. We provided reviewers with a partial
draft of this document. We received responses from all five of the peer
reviewers that we contacted. The peer reviewers generally agreed that
we accurately described the species and its habitat requirements; that
we provided accurate review and analysis of factors
[[Page 27769]]
affecting the species; that our assumptions and definitions of suitable
habitat were logical and adequate; that there were few oversights,
omissions, or inconsistencies in out draft document; and that we used
pertinent literature to support our assumptions and conclusions. One
reviewer was generally critical of the synthesis of information
regarding threats to mountain plover habitat, especially our assessment
of wintering habitat in the Imperial Valley. One reviewer limited
comments primarily to population trends. The peer reviewers provided
suggestions to improve this final document. Recommended editorial
revisions, clarifications, and other changes have been incorporated
into the final document as appropriate. We respond to all substantive
comments below or through changes to the final document.
Comments From Peer Reviewers
(1) Comment: Three reviewers questioned specific details of our
range map.
Our Response: Figure 1, depicting the mountain plover's range, was
developed based on those in Knopf and Wunder 2006, and Andres and Stone
2009, with modifications based on our review of recent information. Our
map depicts generalized areas believed to support breeding and
wintering mountain plover, and does not depict localized areas of
presence or absence. We made some revisions to our range map based on
reviewer comments.
(2) Comment: One reviewer pointed out that while mountain plover
are attracted to burned areas on their breeding ground, there is little
evidence as to whether such burned areas benefit breeding mountain
plover (for example, through higher nest success or fledging success)
compared to habitats they may otherwise use.
Our Response: Reduced vegetative cover resulting from burning
appears more attractive to mountain plover than similar habitat left
unburned. However, we agree that studies have not documented the
specific relationship of burning to successful mountain plover nesting.
(3) Comment: One reviewer stated that estimates of annual survival
should be considered minimum estimates, because studies do not control
for permanent migration of mountain plover (i.e., they assume birds not
accounted for have died rather than moved away from the study area).
Our Response: We agree and have acknowledged this in the text.
Studies in Montana have produced the most complete information on
juvenile (first year of life) and adult mountain plover annual survival
rates, but the extent to which these studies underestimate survival
rates due to emigration is not known.
(4) Comment: One reviewer asserted that recent literature clearly
identified adult survival as a vital importance to productivity and
survival of shorebird populations.
Our Response: We agree. In the limited studies that have estimated
adult survival of mountain plover, adult mountain plover survival
appears relatively high. The suggestion that management efforts to
increase mountain plover populations might best be targeted at
increased chick survival (hatching to fledging) result, in part, from
data showing relatively low and highly variable survival of mountain
plover chicks (see Survival, Lifespan, and Site Fidelity above).
(5) Comment: Two reviewers noted that while the mountain plover may
have a long lifespan compared to many other shorebirds, some shorebirds
do live longer and other bird families, such as seabirds, live much
longer.
Our Response: Mountain plover in the wild have been known to live
to over 10 years. We have qualified our description of the mountain
plover as a ``relatively'' long-lived species.
(6) Comment: One reviewer suggested that mountain plover fidelity
to breeding sites is more regional than site-specific and that
differences in habitat across the mountain plover breeding range may
influence site fidelity.
Our Response: Both may be correct. Lack of genetic differentiation
found by Oyler-McCance et al. (2005, p. 359; 2008, pp. 496-497) suggest
that mixing of mountain plover across regions is also occurring.
(7) Comment: One reviewer suggested that we discuss spatial and
temporal variation in long-term and recent BBS trend data for the
mountain plover and cited a long-term (1966 through 2009), negative New
Mexico trend as the only statistically significant population trend
among the rangewide or Statewide BBS trend estimates we provide.
Our Response: We have included data pertinent to spatial and
temporal (by State and long-term versus short-term) trends in mountain
plover populations in this document when available (see Conservation
Status and Local Populations above). These statistics are based on
fewer data and generally appear less reliable than rangewide trends.
The long-term trend estimate in New Mexico is unique among those we
cite, in that it reflects a statistically significant indication of at
least some decline.
(8) Comment: One peer reviewer stated that there is insufficient
information about the distribution and status of the mountain plover in
Mexico to evaluate whether past, present, or future loss of prairie
dogs and the ecosystem they support in Mexico is a significant threat
to the mountain plover.
Our Response: We agree that information on the distribution and
status of the mountain plover in Mexico is limited. Based on the
information available, past loss of prairie dogs colonies in Mexico has
decreased available mountain plover habitat and may have had some
adverse impact on the mountain plover. Recent Mexican and international
attention to conservation of prairie dogs and grassland complexes in
Mexico improves prospects for maintaining existing mountain plover
wintering habitat (see Factor A below). While future losses of prairie
dog colonies in Mexico may occur, we do not believe that associated
impacts to mountain plover's habitat present a significant threat to
the mountain plover over its wintering range.
(9) Comment: One reviewer stated that discussion of habitat loss to
land use modification would be greatly improved by including specifics
of how these losses fall within the precise breeding and wintering
habitats of the mountain plover. Two reviewers contended that the
relative threat posed by agricultural conversion (of grasslands) was
difficult to assess unless analyzed at a fine spatial scale.
Our Response: The mountain plover's breeding and wintering ranges
extend across a large area and encompass a variety of habitat types. We
have addressed habitats supporting the mountain plover, habitat losses,
and threats to mountain plover habitat on a rangewide and regional
level, and in some cases on a State or local level as well.
(10) Comment: One reviewer offered that uncertainties regarding
future agricultural practices on private lands emphasized the
importance of managing for the mountain plover on State and Federal
lands.
Our Response: A great degree of uncertainty exists regarding future
agricultural practices on private lands, but we believe that changes in
agriculture are not likely to significantly threaten the mountain
plover in the foreseeable future. Across the range of the mountain
plover there are currently many initiatives, on both public and private
lands, to manage habitat for wildlife including the mountain plover,
bird species using similar habitats, and
[[Page 27770]]
prairie dogs (see Factor A discussion below). The mountain plover has
been designated a bird of conservation concern by the Service (2008)
and has special conservation status in many States (see Conservation
Status and Local Populations above and Factor A discussion below). We
anticipate and support continued emphasis on mountain plover
conservation and management by our Federal and State partners.
(11) Comment: One reviewer noted that, without synthesis of exactly
what agricultural lands mountain plover require on their wintering
areas and how those specific fields are threatened (for example,
fallowing of crop fields in California's Imperial Valley), our
conclusion that threats impacting only a small portion of agricultural
lands would not affect mountain plover was problematic.
Our Response: In Migration and Wintering Habitat above, we describe
wintering habitats favored by the mountain plover. In Factor A below we
discuss threats that may impact these habitats, including threats to
certain crop types favored by the mountain plover. The level of
analysis we provide is sufficient to evaluate threats to the mountain
plover from changes on agricultural lands that provide wintering
habitat and utilizes the best available information we have regarding
this topic. Without specific information to suggest otherwise, we
conclude that threats would not disproportionately impact those
particular fields that presently receive, or in the future would
receive, most use by the mountain plover.
(12) Comment: One reviewer noted that the Imperial Valley,
California, an area supporting significant numbers of wintering
mountain plover, is one of the fastest growing areas of the United
States.
Our Response: From 1984 to 2008, urban area in the Imperial Valley
increased by 6,000 ac (2,400 ha) (CDC 2010), much of it outside of
croplands favored by the wintering mountain plover. About 381,000 ac
(154,000 ha) of field crops are present in the Imperial Valley
(Imperial Irrigation District (IID) 2009a). We concluded that
population growth and urban expansion is having a modest impact on
Imperial Valley croplands, but does not rise to the level of a threat
to the species (see Factor A discussion below).
(13) Comment: One reviewer stated that, over the wintering range of
the mountain plover, increase in human population, associated land use
changes, and reductions in available water for agriculture would impact
areas currently used by mountain plover. The reviewer concluded that
because there was ``lack of suitable habitat to move to,'' this would
be detrimental to mountain plover.
Our Response: Human development and changes in agriculture,
including changes brought on by future water availability, are likely
to impact some of the areas currently used by wintering mountain plover
in California, in southern Arizona, and elsewhere in their wintering
range. Based on the likely magnitude of such changes and the extensive
wintering range of the mountain plover, we conclude that loss of
wintering habitat is not likely to be a significant threat to the
mountain plover in the foreseeable future (see our discussion in Factor
A below).
(14) Comment: One reviewer questioned whether mountain plover are
impacted by pesticides and herbicides used on sod farms where they are
often seen during migration or in winter.
Our Response: We have found no documentation of effects to mountain
plover from exposure to pesticides on sod farms. However, in the past,
the use of diazinon, an organo-phosphate pesticide, on sod farms may
have impacted the mountain plover. In 1988, after documented large die-
offs of birds of other species, the U.S. Environmental Protection
Agency (EPA) cancelled the registration of diazinon for use on golf
courses and sod farms (EPA 2006, p. vii). We have no information
regarding significant harm of any bird species since 1988 that is
attributable to use of pesticides on sod farms.
(15) Comment: One reviewer suggested more discussion on invasive
grasses and their impact on mountain plover.
Our Response: Invasive plants, including nonnative grasses planted
as forage for cattle, are widespread across the western United States.
Many invasive plants grow to a density or height that can make habitat
unsuitable for mountain plover. While perceived by some as a potential
threat, the effects of nonnative grasses and invasive plants on the
mountain plover have not been well documented. Within the ecosystems it
inhabits, the mountain plover is best supported where native or
domestic herbivores, fire, dry conditions, soil conditions, or
disturbance create low, sparse vegetation. In general, this is true
whether the vegetative community consists only of native vegetation or
also supports a component of nonnative or invasive plants.
Public Comments
Process Issues
(16) Comment: One commenter stated that e-mails, personal
communications, and letters that the Service referenced in support of
the December 5, 2002, listing proposal (67 FR 72396) do not meet the
best information available standard as described in Service policy (59
FR 34271, July 1, 1994).
Our Response: Our policy, as cited above, requires that we evaluate
all scientific and other information available, which includes both
published and unpublished materials, in the development of a listing
action. We review the information regardless of origin, and determine
whether it is reliable, is credible, and represents the best
information available regarding the species under review. We document
our evaluation of any information we use in making our decision,
whether it supports the decision or not.
(17) Comment: Commenters believed that our analysis in our February
16, 1999, and December 5, 2002, proposals to list the mountain plover
(64 FR 7587 and 67 FR 72396, respectively) used ``selective science''
to defend our position, while ignoring information contrary to our
conclusion.
Our Response: We base our determinations on review of all pertinent
information available. This final determination is further based on
substantial new and additional information available since our previous
actions.
(18) Comment: One commenter stated that in the 1999 and 2002
proposals to list the mountain plover (64 FR 7587 and 67 FR 72396,
respectively) the Service did not identify or quantify actual threats,
and therefore the Service has not shown that mountain plover have
declined or are at risk.
Our Response: In this final determination, we have evaluated the
relative security of the species from present and foreseeable threats
across its breeding, migratory, and wintering range. Where available
information has allowed, we have identified and quantified actual
threats to the mountain plover in this evaluation. While threats,
especially future threats, may be difficult to quantify, we evaluate
threats based on analysis of the best scientific and commercial
information available.
(19) Comment: One commenter stated that e-mails and faxes should be
accepted as comment on the proposed listing.
Our Response: Our policy requires submission of written comments
through the Internet (via the Federal
[[Page 27771]]
eRulemaking Portal at http://www.regulations.gov), or by U.S. mail or
hand-delivery, and we believe this provides the means for all
interested parties to provide comments, information, and
recommendations.
(20) Comment: Various commenters suggested that there are either
more or fewer reasons for listing the mountain plover now compared to
2003 when our proposed listing was withdrawn (68 FR 53083, September 9,
2003).
Our Response: Our 2003 decision was vacated by the Court and is not
relevant to this final determination regarding the mountain plover. We
have based our determination on the current status of the mountain
plover and current and future threats to the species, based on the best
scientific and commercial information available to us at this time.
Issues Regarding Range, Numbers, and Populations Trends
(21) Comment: One commenter questioned our emphasis on the PNG in
Colorado and Charles M. Russell National Wildlife Refuge (NWR) in
Montana in our proposals to list the mountain plover, as relatively few
mountain plover breed in either site.
Our Response: We agree that neither site currently supports a large
percentage of the total mountain plover population. Both sites are
Federally controlled and have supported mountain plover research and
management efforts. The PNG once likely supported the highest density
of mountain plover in the species' breeding range. The dramatic loss of
this sizable population has relevance to the rangewide population trend
and may provide insight to current and future threats to the mountain
plover. Charles M. Russell NWR provides management opportunities on a
Montana site representative of those where mountain plover is largely
dependent on the black-tailed prairie dogs to create desirable habitat
conditions.
(22) Comment: One commenter stated that breeding habitat on public
and private lands in the mountain plover's range has not been
adequately surveyed and suggested that additional surveys will
consistently find more mountain plover.
Our Response: Knowledge of mountain plover populations varies
greatly across the breeding range. Surveys vary in methodology and
scope. In some cases, lack of access to conduct surveys on private
lands limits the accuracy of population estimates. Based on information
available since 2002, estimates of mountain plover breeding numbers in
certain States and throughout the range have been modified. Former
rangewide population estimates were based on surveys of mountain plover
in California, where the vast majority of birds were thought to winter.
Our current rangewide population estimate is based on minimum breeding
range population estimates. However, no estimate currently exists that
provides a precise estimate of rangewide numbers.
(23) Comment: One commenter dismissed population estimates as
``just a guess.''
Our Response: We believe that some structured studies on the
breeding range have produced population estimates that approximate the
actual numbers of mountain plover that are present. In other cases,
estimates may be limited to the minimum number of individuals known, or
may suggest the likely population size based on limited data. While we
summarize population estimates and seek to understand population
trends, numbers alone are not the basis for listing determinations
under the Act. Listing determinations are based on whether there are
threats present or likely to occur that would result in the species
being in danger of extinction or likely to become so within the
foreseeable future.
(24) Comment: Several commenters cited increased rangewide
population estimates as a reason why the mountain plover does not merit
listing. One commenter cited the recent status change by the IUCN
(downlisting from ``vulnerable'' to ``nearly threatened'') as evidence
of reduced threat to the species.
Our Response: While greater abundance suggests less vulnerability,
we have no basis to suggest that the increased estimate of mountain
plover numbers reflects an actual, rangewide increase. The number of
individuals of a species present is only one factor considered when
assessing vulnerability to extinction. Current and future threats may
be of greater significance. Downlisting by the IUCN was based on
revised population estimates alone, and not on changed interpretation
of threats present.
(25) Comment: One commenter noted that all wintering areas in the
United States and Mexico have not been located and opined that further
searching is likely to yield more wintering sites.
Our Response: While more information overall has been gathered
since our 2002 proposal (67 FR 72396, December 5, 2002), much is still
unknown regarding wintering habitat. Rangewide breeding population
estimates and wintering estimates from California suggest that a
substantial percentage of mountain plover winter elsewhere. Because the
large flock sizes observed in California are not regularly encountered
elsewhere, mountain plover numbers may occur at lower densities in
other parts of their wintering range.
(26) Comment: One commenter stated that the former estimate of
20,000 breeding mountain plover at the PNG in the 1970s may have been
off by an order of magnitude.
Our Response: While the actual number present in the 1970s is
unknown, it is well established that mountain plover populations on the
PNG have greatly decreased since that time, with relatively few
breeding mountain plover present since the mid-1990s.
(27) Comment: One commenter questioned our estimates of up to
10,000 mountain plover at Kern NWR in California during the 1960s.
Our Response: Many mountain plover used Kern NWR in winter during
the 1960s, but the 10,000 estimate is by far the largest recorded
(Engler 1992). We believe estimates at Kern NWR approximate mountain
plover numbers attracted to the refuge by favorable habitat conditions
previously present.
(28) Comment: Multiple commenters mentioned continued, significant
declines across the breeding and wintering range of the mountain
plover, as cited by researchers, as indicative of the species'
imperiled status.
Our Response: Documentation of historical range contraction and
apparent decline in mountain plover populations is reflected in long-
term BBS and CBC trends. Despite more intensive study in recent years,
it is not clear if, or to what extent, any declines in mountain plover
populations continue. See our discussion of Population Size and Trends
above.
(29) Comment: A few commenters stated that BBS and CBC data and
trends regarding mountain plover are unreliable. Others state that
these data are a reason for concern.
Our Response: The BBS is the best available long-term trend
information for the mountain plover on its breeding range. It is an
imprecise indicator of mountain plover population trends. These data
appear to confirm a decline over the period 1966 through 2009, but
results suggest that the rate of any continued (1999 through 2009)
decline has moderated. The CBC data are more restricted in geographic
scope than are the BBS data, but these data also suggest a long-term
decline. Few CBC count circles regularly report mountain plover, and
numbers are highly variable, likely reflecting mobility of wintering
flocks.
[[Page 27772]]
See our discussion of Population Size and Trends above.
(30) Comment: We received a comment that insufficient data are
available to predict any trend toward extinction.
Our Response: We agree that current trend data are limited and that
the ability to project future population trends is difficult. However,
we have reviewed the best population and trend data available as part
of our analysis of the mountain plover's status. In making our final
listing determination, we not only looked at population trends, but we
have also evaluated the best available information on current and
future threats to the species.
(31) Comment: One commenter suggested that population trends at the
PNG, where the birds have been closely studied, are indicative of the
overall population trend for the mountain plover.
Our Response: Knopf (2008, p. 61) summarized mountain plover
studies on the PNG in Weld County, Colorado, and suggested reasons for
that population's former abundance and more recent decline, including
long-term changes in habitat since abandonment of agricultural fields
following the ``Dust Bowl'' of the 1930s. We believe that this
represents a unique history because long-term BBS data (Sauer 2010a)
suggest a relatively stable population in Colorado despite the dramatic
drop in numbers on the PNG. In 2008, Knopf expressed the opinion that
similar numbers of mountain plover were breeding in Weld County as in
1990, just not on the PNG (Knopf 2008, p. 54). We have no scientific
information that would point to the precipitous decline in mountain
plover historically at the PNG as indicative of the overall mountain
plover population trend.
(32) Comment: One commenter suggested that mountain plover numbers
are dynamic, and that their current abundance is within the range of
normal fluctuation due to annual variation in weather patterns.
Our Response: Breeding numbers and nest success can vary locally
based on a number of factors including weather. However, the historical
reduction in rangewide mountain plover numbers seems well
substantiated. Interpretation of recent trends is made more difficult
by short-term variability in population numbers that may reflect annual
weather variation. The effect of all factors, natural and human-caused,
that may contribute to the survival of the mountain plover is
considered in this determination, including variation in weather
patterns and longer-term changes in climate.
Species Vulnerability
(33) Comment: One commenter referenced the mountain plover's
relatively short lifespan as contributing to the vulnerability of
populations to extirpation if one or more years of unfavorable habitat
on their breeding grounds prevent successful nesting.
Our Response: As discussed above in our discussion of Population
Size and Trends, and under Factor E below, our former conclusion that
the lifespan of mountain plover contributed to its vulnerability has
been refuted based on more recent information. The mountain plover is
now considered a relatively long-lived species, with one individual
documented living for 10 years (Dinsmore 2008, p. 52). We do not
believe that mountain plover lifespan substantially influences the
vulnerability of mountain plover to extinction.
(34) Comment: One commenter stated that breeding mountain plover
populations are often discontinuous, in part because of habitat
fragmentation, and stated that local, isolated mountain plover
populations have an increased vulnerability to random natural and
human-caused events.
Our Response: It is generally true that small and isolated
populations are less secure than larger populations. While the mountain
plover is a migratory, highly mobile species, it generally returns to
the same breeding sites, which isolates local populations to a degree.
Small mountain plover populations are vulnerable to ``blinking out'' if
events destroy or degrade habitat. This vulnerability may be offset by
the species' ability to colonize new habitat as it becomes available.
Recent studies describe mountain plover dispersal from natal sites or
former breeding sites, and suggest that the mountain plover has been
able to disperse and exploit habitat nearby if former habitat is
destroyed.
Prairie Dog Issues
(35) Comment: We received numerous comments regarding mountain
plover and prairie dogs. They included comments regarding the mountain
plover's dependence on prairie dogs, and the distribution, abundance,
and trends in prairie dog populations. One commenter contended that if
the black-tailed prairie dog does not merit listing, then the mountain
plover does not either.
Our Response: It is well established that in parts of its range,
Montana in particular, the mountain plover is largely dependent during
breeding on the habitat that prairie dogs create and maintain.
Elsewhere, mountain plover also breed in a variety of habitats,
including prairie, semi-desert, and cropland. See our discussion
regarding the status and threats to the black-tailed prairie dog and
potential effect on the mountain plover in Factor A below. We recently
determined that the black-tailed prairie dog does not warrant listing
under the Act (74 FR 63343, December 3, 2009), but it does not follow
that this would automatically lead to a similar conclusion for the
mountain plover since the species could be subject to a variety of
threats unrelated to the status of prairie dogs.
(36) Comment: We received a comment that the Service in 1999 and
2002 underestimated the presence of prairie dogs and therefore their
habitat and the number of mountain plover that prairie dog colonies
supported.
Our Response: Our current analysis includes information developed
since 2002. Under Factor A below, we discuss current estimates of
prairie dog abundance and implications of prairie dog numbers to
mountain plover.
(37) Comment: Some commenters stated that black-tailed prairie dogs
lack protection, are often poisoned or shot, and are often affected by
sylvatic plague; therefore, prairie dog colonies and the mountain
plover they support remain vulnerable.
Our Response: We agree that there are few protections for the
black-tailed prairie dog. However, despite the above factors, the
black-tailed prairie dog has increased in number throughout all States
in its range in the United States since the 1960s. In the United
States, we do not foresee any significant decreases in black-tailed
prairie dog populations or the habitats they create. On December 3,
2009, the Service published a 12-month finding that the black-tailed
prairie dog is not threatened with extinction and is not likely to
become so in the foreseeable future (74 FR 63343). In Mexico, both the
black-tailed prairie dog and the Mexican prairie dog continue to be
reduced in number and distribution, and this likely impacts mountain
plover habitat. See our discussion under Factor A below.
(38) Comment: Other commenters cited conservation efforts that
target prairie dogs, as well as efforts to conserve greater sage-grouse
(Centrocercus urophasianus), lesser prairie-chicken (Tympanuchus
pallidicinctus), and black-footed ferret (Mustela nigripes), and
concluded that these existing efforts make mountain plover conservation
efforts unnecessary.
Our Response: Efforts to conserve these species are in response to
declines in numbers and threats to their future existence. While the
mountain plover
[[Page 27773]]
will benefit from conservation of prairie dogs, some other species
require habitats unlike those favored by the mountain plover. To the
extent that mountain plover benefit from conservation efforts for other
species, these are addressed under Factor A, below.
(39) Comment: One commenter contended that the presence of prairie
dogs was only one of several factors that create mountain plover
breeding habitat and that soil type, soil moisture, cattle grazing,
fire, and incidence of drought all play a role in supplying suitable
mountain plover breeding habitat.
Our Response: While the literature on the mountain plover is
replete with the association of mountain plover and prairie dog
colonies, we agree that other factors, singly or in combination, can
shape mountain plover breeding habitat, and we have taken this into
consideration in this final listing determination.
Grassland Conversion and Agricultural Issues
(40) Comment: Multiple commenters state that grassland conversion
to cropland is a significant threat.
Our Response: While grassland conversion contributed to past
contraction in the mountain plover's range and reduction of the
mountain plover's numbers, much of this took place on the eastern Great
Plains where conversion to crops such as corn and soybeans was
feasible. The rate of grassland conversion is now much reduced. We do
not believe that the current or anticipated future conversion of
grasslands to other uses is a significant threat. Dryland agriculture,
found in the southern portions of the mountain plover's breeding range,
supports significant numbers of breeding mountain plover. The extent to
which the use of dryland agricultural habitat is beneficial to the
mountain plover is largely undetermined. See our discussion under
Factor A below.
(41) Comment: One commenter contended that current farming
practices benefit breeding mountain plover, that mountain plover are an
adaptable species that have shifted from grasslands to cultivated lands
on both their breeding and wintering areas, and that cultivated lands
are now the most important habitat for the mountain plover. Other
commenters raised the question of whether the choice to nest in
cropland is detrimental to mountain plover.
Our Response: Research findings from Colorado present a complex
picture. Hatching success on some croplands is similar to that found on
grasslands with or without prairie dogs. Chick survival appears to be
lower on crop fields, but results of some studies differ, perhaps
depending on variables such as annual weather conditions and site-
specific levels of predation. The influence of the agricultural
landscape on mountain plover recruitment has not been fully determined.
Wintering mountain plover favor crop fields at times, but habitat
preference seems to vary greatly by region. Mountain plover use of crop
fields in winter may reflect the loss of preferred native habitats.
(42) Comment: One commenter stated that farming practices on the
prairie have not changed in 50 years and questioned why they could
suddenly be a threat.
Our Response: Dryland farming practices in eastern Colorado and
adjacent States have remained relatively stable, although market
factors may favor one crop over another. Historically, conversion of
prairies to crop fields likely contributed to the decline of mountain
plover, especially in the eastern portion of its range. Farm operations
can directly impact nesting, but the current relationship between
dryland crop fields and breeding mountain plover is complex. However,
the best available information indicates that current agricultural
practices have remained largely unchanged in recent years and have not
been shown to pose a threat to the mountain plover (see Factor A
discussion below).
(43) Comment: Several commenters stated that the Conservation
Reserve Program is beneficial to the mountain plover, while other
commenters thought the program was detrimental to the mountain plover.
Our Response: The U.S. Department of Agriculture (USDA) administers
the Conservation Reserve Program, which allows producers to retire
agricultural lands for a 10-year period, thereby benefitting wildlife
and other resources. Most of these lands are planted with nonnative
grasses that support other wildlife species but often do not create
mountain plover habitat. The program likely has little effect on
overall mountain plover habitat because a relatively small portion of
agricultural fields are retired at any one time and retired lands
provide minimal benefit to mountain plover.
(44) Comment: Commenters expressed concern that anticipated human
population growth in South Park, Park County, Colorado, and the
fragmentation of existing habitat there, will impact a significant
mountain plover population.
Our Response: We agree that buildout of private lands in South Park
would adversely affect the mountain plover breeding population that is
currently present. However, based on information from Park County,
population growth is much slower than once predicted, and we do not
anticipate substantial human development will occur in the area in the
foreseeable future. See our discussion under Factor A below.
Livestock/Grazing/Range Management
(45) Comment: One commenter stated that range management has
contributed to the past decline of mountain plover and is a current
threat, as practices vary little from those used previously.
Our Response: Range management is often designed to maximize forage
and diminish excessive disturbance to grass and soil. Such management,
when employed, does not benefit the mountain plover. However, we do not
see range management as representing a current or future threat to the
mountain plover, as there is no information to suggest that current
range management practices and the habitat conditions now present are
likely to change substantially in the future.
(46) Comment: One commenter cited recommendations by Knopf and
Wunder (2006) to prioritize research regarding varied livestock grazing
practices and their effects on mountain plover.
Our Response: Research is ongoing as to how range management
affects mountain plover and a variety of other grassland species. We
have a basic understanding of how livestock grazing can enhance
mountain plover habitat (Dechant et al. 2003, entire).
(47) Comment: Commenters cited the decline in sheep (Ovis aries)
numbers in the mountain plover's breeding range as detrimental to
mountain plover.
Our Response: Sheep grazing helps maintain low vegetation structure
favored by the mountain plover. The U.S. sheep industry has been in
decline since the 1940s. Past declines in sheep may have contributed to
losses in mountain plover breeding habitat. The future of the sheep
industry in the United States is difficult to predict. See our
discussion under Factor A below.
(48) Comment: One commenter stated that cattle do not replace the
role of bison in the ecosystem, and that the role of cattle grazing as
it relates to insect availability has not been adequately evaluated.
Our Response: The historical loss of bison resulted in a number of
changes to the prairie ecosystem. Current mountain plover numbers and
distribution, and our evaluation of threats to the species, are based
on an ecosystem largely devoid of bison.
[[Page 27774]]
Insect numbers and availability to mountain plover under various
grazing regimes may be worthy of investigation.
Mineral Extraction/Energy Development
(49) Comment: We received many comments on the threat to the
mountain plover posed by oil and gas field development, and wind energy
development. Commenters stated that effects of energy development on
the mountain plover are largely unknown and that the mountain plover's
response to oil, gas, and wind energy development should be
investigated.
Our Response: We discuss the potential impact of energy development
on mountain plover under Factor A below. Wells, turbines, roadways, and
related development constitute potential threats. While far from
definitive, recent studies suggest mountain plover may be little
affected by oil and gas development. Thus far, we have no data on the
effect of wind energy development on wintering mountain plover.
(50) Comment: One commenter recounted the history of mountain
plover presence at the Antelope Coal Mine in Wyoming and suggested that
mountain plover are tolerant of both ground disturbance and nearby
industrial activity.
Our Response: We agree that results of monitoring at this site
confirm the mountain plover's preference for open ground created by
disturbance and a general tolerance of human activity. While mining
activity displaces mountain plover, reclamation following mining may
restore habitat.
(51) Comment: One commenter described new wind energy projects
under development in southern Texas areas where mountain plover winter
and thought that the species would be affected by the presence of
turbines.
Our Response: As stated earlier, thus far, we have no data on the
effect of wind energy development on wintering mountain plover. The
response of mountain plover to turbines on their breeding areas (which
indicates some degree of tolerance) may not provide insight into how
flocks respond in winter.
(52) Comment: One commenter noted conservation efforts to limit
energy development on State-designated greater sage-grouse Core
Breeding Areas in Wyoming, which include 36 percent of likely mountain
plover breeding habitat in the State. The commenter suggested that this
will provide a significant measure of protection for the mountain
plover.
Our Response: While limitations on energy development in these
areas may reduce potential for any associated adverse impacts on the
mountain plover, there is uncertainty as to whether such measures will
persist into the future. Designated greater sage-grouse Core Breeding
Areas are broad and encompass habitats that support mountain plover,
but from a habitat perspective, the needs of the two species differ.
Measures to manage for the greater sage-grouse may not benefit the
mountain plover.
(53) Comment: One commenter suggested that the Service should base
its analysis of the energy development threats on what is known
regarding the impact of roads, habitat conversion, and fragmentation.
Others raised the issue of roads and structures resulting in increases
in mammalian and avian predators of mountain plover, which in turn
could lead to higher mortality of mountain plover chicks and adults.
Our Response: In general, while some other species have been shown
to be adversely impacted by energy development, we have little evidence
of similar impacts on the mountain plover. Changes in habitat brought
on by energy development, including the potential that roads and
structures may facilitate increased predation on the mountain plover,
are addressed under Factor A and Factor C below. Some adverse impacts
are likely, but there may also be offsetting benefits resulting from
the increase in bare ground preferred by the mountain plover.
(54) Comment: One commenter noted that the Western Governors
Association, States, and the wind industry have been addressing
concerns regarding construction of wind energy projects on sensitive
wildlife areas.
Our Response: The Service is engaged with the wind industry and
other partners on issues regarding a range of wildlife including the
endangered whooping crane (Grus americana), and candidates including
the greater sage-grouse, lesser prairie chicken, and Sprague's pipit
(Anthus spragueii), as well as the mountain plover. We anticipate that
current emphasis on renewable energy projects will be accompanied by
cooperative initiatives to minimize impacts to species of concern.
(55) Comment: One commenter was concerned that mountain plover
populations could decrease significantly while studies on impacts from
energy development were ongoing and that precautionary measures should
be enacted to preclude potential impacts.
Our Response: The USFS and BLM have designated the mountain plover
a sensitive species within portions of the range (see discussion under
Factor D below). These agencies address potential impacts to the
species when reviewing energy development. However, we will continue to
work with these and other Federal agencies, States, and other partners
to monitor the status of the mountain plover.
Wintering Habitat
(56) Comment: We received many comments on actual or potential loss
of wintering habitat in California and how this could affect rangewide
populations of mountain plover. Commenters stated that the historical
and ongoing conversion of grasslands in California is a threat to the
mountain plover. Some commenters cited Andres and Stone (2009, p. 1),
describing crucial threats facing the mountain plover, including ``* *
* the inability to manage agricultural lands in the Imperial Valley,
California, to provide consistent winter habitat, and the loss or
inadequate management of other known wintering areas in California.''
Our Response: Much of the native grassland that the mountain plover
formerly used for wintering in California has been lost. While the
mountain plover has shown a preference for native and nonnative
grasslands in California, especially when heavily grazed, the mountain
plover has successfully switched to using crop fields. Additional
conversion of grasslands to various other lands uses may increase
mountain plover dependence on these crop fields. Any resulting adverse
effects of this change are largely speculative.
Based on a variety of existing and projected trends in land use,
the further reduction of grassland and crop fields used by mountain
plover for wintering in California seems likely. However, as of 2007,
California supported over 25 million ac (10 million ha) of land in
farms, including 9.5 million ac (3.8 million ha) of cropland, 5.5
million cattle, and 600,000 sheep (USDA 2010). The mountain plover is a
highly mobile species that uses habitat opportunistically in winter.
The mountain plover's preference for certain agricultural lands above
others is well documented. However, the pervasive expanse of
agriculture throughout the Central Valley and Imperial Valley suggests
to us that, while current and foreseeable future changes may reduce
favored wintering habitat, the quantity and variety of agricultural
habitat remaining in California will continue to provide sufficient
wintering areas for the mountain plover.
(57) Comment: One commenter noted that in the Imperial Valley, an
important wintering area for mountain plover, the
[[Page 27775]]
area of bermudagrass and alfalfa (crops favored by the mountain plover)
has declined.
Our Response: Both bermudagrass and alfalfa show recent declines in
area from 2005 to 2009 (Imperial Irrigation District (IID) 2010). While
area devoted to all hay (including bermudagrass and alfalfa) in the
Imperial County varies yearly, 233,000 ac (90,000 ha) were present in
both the 1997 and the 2007 (USDA Census of Agriculture (USDA) 2010). We
do not have evidence indicating the likelihood of long-term future
declines in acreage devoted to these two crops.
(58) Comment: One commenter noted that the wintering range of the
mountain plover in Texas is not well described and that the species'
occurrence in Texas is variable. There was concern that habitat needs
were not understood and that Texas populations were not receiving the
attention they merited.
Our Response: We agree that knowledge of mountain plover wintering
in Texas has been scant (as described in Conservation Status and Local
Populations above). Distribution is largely limited to private lands
where land use has varied little and where few threats are known. New
efforts to survey abundance and habitat use of mountain plover in Texas
are currently under way.
Pesticides
(59) Comment: Some commenters expressed concern that use of
pesticides to control grasshoppers (family Acrididae) and the Mormon
cricket (Anabrus simplex) reduces foods that sustain breeding mountain
plover, especially chicks, in the mountain plover's breeding range.
Our Response: Efforts to control grasshoppers and Mormon crickets
are generally limited to suppressing populations in years and in areas
where infestations occur, and have the goal of reducing densities to
limit economic impacts. While at times local mountain plover
populations could be affected by these activities, we do not believe
that grasshopper and Mormon cricket control represents a significant
threat to mountain plover populations. See our further discussion under
Factor E below.
Climate
(60) Comment: Some commenters suggested that climate change could
bring warmer and drier conditions that may benefit mountain plover
breeding.
Our Response: Mountain plover breeding numbers and breeding success
can vary greatly based on a number of factors, including annual weather
variation. Anticipated changes in climate will alter annual norms of
temperature and precipitation, but those changes will likely vary
across the mountain plover's breeding and wintering range (see
discussion under Factor E below). Overall, we believe it is speculative
to conclude that these effects will be beneficial to the mountain
plover.
Conservation Efforts and Effects of Listing
(61) Comment: Several commenters noted that conservation
partnerships between State agencies, landowners, and conservation
groups have promoted conservation of mountain plover and that listing
would negate some gains in cooperation.
Our Response: We agree that partnerships are important to the
conservation of the mountain plover, especially in those States where
mountain plover occur mostly on private lands. The concern that such
partnerships could be affected by listing is legitimate, but is not a
factor evaluated when determining whether a species warrants listing
under the Act.
(62) Comment: One commenter suggested that traditional land uses on
private land would continue even if listing occurred. Another commenter
suggested listing under the Act would decrease the ability to
effectively manage habitat, slowing management response to changing
science and conditions on the ground. A third commenter suggested
listing would provide impetus for needed research.
Our Response: We agree that listing under the Act could lead to
multiple outcomes, including those above. We considered all available
scientific and commercial information in making our determination as to
whether the mountain plover is currently, or may in the foreseeable
future become, in danger of extinction.
(63) Comment: Several commenters emphasized the importance of
developing a special rule under section 4(d) of the Act to exempt
certain activities from the take provisions of the Act should the
mountain plover be listed.
Our Response: In our June 29, 2010, document (75 FR 37353) we
addressed the possible development of a special 4(d) rule if the
mountain plover were listed as threatened. The intent was to develop a
mechanism by which agricultural practices that might result in take,
but were believed to have no net adverse impact on the mountain plover,
could continue. Development of such a rule would allay some concerns
associated with listing and would contribute to continued cooperation
efforts with private landowners. Were we to determine that the mountain
plover met the definition of a threatened species, we would consider
developing a special rule under section 4(d) of the Act. However,
because we determined that the species does not warrant listing, the
consideration of a special 4(d) rule is not necessary.
Summary of Information Pertaining to Five Factors
Section 4 of the Act (16 U.S.C. 1533) and implementing regulations
(50 CFR 424) set forth procedures for adding species to the Federal
Lists of Endangered and Threatened Wildlife and Plants. Under section
4(a)(1) of the Act, a species may be determined to be endangered or
threatened based on any of the following five factors:
(A) The present or threatened destruction, modification, or
curtailment of its habitat or range;
(B) Overutilization for commercial, recreational, scientific, or
educational purposes;
(C) Disease or predation;
(D) The inadequacy of existing regulatory mechanisms; or
(E) Other natural or manmade factors affecting its continued
existence.
The February 16, 1999 (64 FR 7587), proposed listing rule provided
a description of threats affecting the mountain plover under the five
listing factors identified in section 4(a)(1) of the Act. The December
5, 2002, proposal (67 FR 72396), which was described as a
``supplemental proposal,'' provided pertinent new information. Both of
the proposed rules concluded that the mountain plover was likely to
become an endangered species in the foreseeable future unless measures
were taken to reverse its decline. Conservation measures to reverse the
decline were discussed in both of the proposals.
In our February 16, 1999, proposed rule to list the species (64 FR
7587) and our December 5, 2002, proposed rule to list the species (67
FR 72396) we described a number of potential threats to the mountain
plover. We cited historical decline in the black-tailed prairie dog (98
percent range wide) and its effect on mountain plover habitat. We
described effects of past rangeland loss to agricultural conversion (30
percent of the Great Plains) and more recent conversion at specific
mountain plover breeding sites. We addressed residential expansion into
a mountain plover breeding area in South Park, Colorado, and stated
that buildout of private lands would be detrimental. We hypothesized
that cultivated areas used for breeding by mountain plover may
[[Page 27776]]
act as a ``population sink'' and that this could impact population
viability. We expressed concern over the rising trend in oil, gas, and
mineral exploration in mountain plover breeding habitat and, while we
suggested habitat changes might not be detrimental, we cautioned that
roads and human disturbance could impact mountain plover breeding. We
cited potential impacts of both historical loss of grasslands and
changing agricultural practices on mountain plover wintering areas in
California. With the Imperial Valley growing in importance to wintering
mountain plover, we suggested that water conservation, water transfer
projects, burning restrictions, urbanization, and resulting
modification of agricultural practices in the Imperial Valley could be
detrimental to mountain plover populations. In our 1999 and 2002
proposals we also expressed concerns regarding the mountain plover's
average life span and breeding site fidelity as factors potentially
impacting persistence of local breeding populations. We described a
short average life span as limiting opportunities for mountain plover
to reproduce. We also suggested that high site fidelity and the
specific breeding habitat that mountain plover required limited
opportunities to disperse to new breeding sites should former breeding
areas turn inhospitable. We addressed concerns over mountain plover
exposure to pesticides; however, we documented no deleterious effects.
In the nine years since our 2002 proposal, substantial new
information has been developed regarding the mountain plover and
potential threats to its existence. Our December 3, 2009, 12-month
finding on a petition to list the black-tailed prairie dog summarized
new information on the species and provided a basis for us to assess
whether threats to black-tailed prairie dog may, in turn, affect the
mountain plover (74 FR 63343). We now believe that the black-tailed
prairie dog is a resilient species and that, overall, populations in
the mountain plover breeding range are not likely to decline. Recent
data confirms that rangeland conversion to agriculture remains
insignificant across the mountain plover's breeding range. Of the
States where we previously documented rangeland declines, none have
experienced significant decline in rangeland in recent years. Expanded
human development of mountain plover breeding habitat in South Park,
Colorado, did not proceed as previously anticipated, and is not
expected to do so in the foreseeable future. Mountain plover use of
cultivated lands has been further investigated, providing insight into
the value of crop lands to breeding mountain plover. It now appears
that perhaps one quarter of the rangewide mountain plover population
breeds in crop fields and little evidence has surfaced to suggest that
is problematic. Energy production in mountain plover habitat continues
to expand, including increased development of oil and gas, and wind
energy projects. Studies to date have not documented adverse impacts of
oil and gas development, or wind energy projects. Effects of such
projects on mountain plover merit continued study, largely because of
their potential future scope. In California, land use changes continue
in the Imperial Valley and elsewhere. However, based on current
rangewide mountain plover population estimates (over 20,000 breeding
birds) we now believe that the majority of mountain plover winter in
areas other than California. We conclude that even with reduction of
California wintering habitat, sufficient area of wintering habitat will
remain, in California and elsewhere, to support current populations.
Life span, site fidelity, and dispersal of both adult and juvenile
mountain plovers have been further investigated. Contrary to our
previous belief, the mountain plover is now considered a relatively
long-lived species. Results of genetic research provide evidence that
mixing among mountain plover breeding populations is occurring.
Dispersal, especially by returning one year old mountain plover,
appears significant. Site fidelity and the mountain plover's ability to
seek out alternative sites for breeding are no longer of concern. While
substantially more information has been developed regarding exposure of
mountain plover to pesticides, no evidence of actual impacts to
individuals, or suggestions that pesticides are having local or
rangewide impacts to the species have surfaced.
The following summary builds on scientific and commercial
information presented in our 1999 and 2002 proposals and provides our
current analysis based on all information currently available.
Factor A. The Present or Threatened Destruction, Modification, or
Curtailment of Habitat or Range
Recent summaries of the mountain plover's status (Dinsmore 2003;
Knopf and Wunder 2006; Andres and Stone 2009) have highlighted the loss
or degradation of mountain plover habitat as the greatest threat to the
species. The primary issues that have been raised are potential loss of
prairie dog populations and the mountain plover habitat they create;
loss of native prairie and rangeland habitats; cropland breeding
habitat as a potential reproductive sink; oil, gas, and mineral
development; wind and solar energy development; loss and changes to
wintering habitat in California; livestock grazing practices; and
urbanization. We address these below.
Threats to Prairie Dogs and Associated Loss of Habitat
Much of the mountain plover breeding range described above follows
the range of the black-tailed prairie dog on grasslands of the Great
Plains from Canada to Mexico. To a lesser extent, mountain plover also
breed within the ranges of the white-tailed, Gunnison's, and Mexican
prairie dogs. Mountain plover often nest in black-tailed prairie dog
colonies at densities greater than in other habitats (Childers and
Dinsmore 2008, p. 707; Tipton et al. 2009, p. 496), and mountain plover
numbers have been shown to track changes in prairie dog abundance
brought on by sylvatic plague (Dinsmore et al. 2005, pp. 1550-1551;
Augustine et al. 2008, unpaginated; Dinsmore and Smith 2010, pp. 42-
44). A common recommendation regarding conservation of the mountain
plover is to assure the maintenance or expansion of black-tailed
prairie dog populations and the landscapes they create (Dinsmore et al.
2005, p. 1552; Augustine et al. 2008; Knopf 2008, p. 61; Andres and
Stone 2009, p. 35; Dinsmore et al. 2010). Current and future threats to
the distribution and abundance of prairie dogs, especially the black-
tailed prairie dog, may in turn be threats to the mountain plover.
On December 3, 2009, the Service published a 12-month finding on a
petition to list the black-tailed prairie dog as endangered or
threatened under the Act (74 FR 63343). We found listing to be not
warranted. Here, we rely heavily on the analysis and results of that
finding to assess the potential threat to the mountain plover from
current or future loss of breeding habitat in the United States that is
created and maintained by the black-tailed prairie dog.
In our December 5, 2002, proposal to list the mountain plover we
discussed historical reduction of the black-tailed prairie dog numbers,
but not current populations or recent population trends (67 FR 72402).
In our 2009 finding regarding the black-tailed prairie dog, we
estimated that 2.4 million ac (1 million ha) of occupied black-tailed
prairie dog habitat exists in a shifting mosaic over time, throughout
an estimated 283 million ac (115 million ha) of suitable habitat. We
evaluated
[[Page 27777]]
recent trends in occupied habitat and considered occupied habitat an
appropriate surrogate for the status of the species. Rangewide, we
estimated historical occupied area of black-tailed prairie dog colonies
to be between 80 million ac and 104 million ac (32 to 42 million ha),
almost all in the United States. Occupied area in the United States had
decreased to a low of 364,000 ac (147,000 ha) by 1961 (largely because
of eradication efforts), and subsequently increased to the 2.4 million
ac (1 million ha) cited above. Throughout the United States, this
represents a 600 percent increase in estimated black-tailed prairie dog
numbers from 1961. See our December 3, 2009, finding (74 FR 63343) for
the methods used to arrive at these estimates and cautions regarding
their accuracy.
The following evaluation of black-tailed prairie dog status
highlights the three States, Colorado, Montana, and Wyoming, which have
the greatest number of breeding mountain plover associated with black-
tailed prairie dog colonies. In Colorado, occupied black-tailed prairie
dog habitat historically existed in the eastern half of the State, east
of the Front Range Mountains (Hall and Kelson 1959, p. 365). Currently,
the distribution of the black-tailed prairie dog is scattered in
remnant populations throughout at least 75 percent of the historical
range (Van Pelt 2009, p. 14). The most recent estimate of occupied
habitat is 788,657 ac (319,158 ha) (Odell et al. 2008, p. 1311). This
is approximately one-third of all currently occupied black-tailed
prairie dog habitat in the United States, and is an eight-fold increase
over occupied habitat thought to be present in Colorado in 1961.
The Conservation Plan for Grassland Species in Colorado
(Conservation Plan) (Colorado Division of Wildlife 2003, p. 1) has a
goal ``to ensure, at a minimum, the viability of the black-tailed
prairie dog and associated species (mountain plover, burrowing owl,
swift fox, and ferruginous hawk (Buteo regalis)) and provide mechanisms
to manage for populations beyond minimum levels, where possible, while
addressing the interests and rights of private landowners.'' The
Conservation Plan includes a species account for mountain plover, but
does not provide any regulatory protections for the species or its
habitat.
In Montana, where mountain plover are strongly associated with
prairie dog colonies (Childers and Dinsmore 2008, p. 701), black-tailed
prairie dog occupied habitat historically existed in the eastern two-
thirds of the State, with the exception of the northeastern corner of
the State (Hall and Kelson 1959, p. 365). Current prairie dog
distribution is scattered in remnant populations over 90 percent of the
historical range (Van Pelt 2009, p. 20). Currently, 193,862 ac (78,453
ha) of occupied habitat are estimated to occur in Montana (Hanauska-
Brown 2009). This represents nearly a seven-fold increase over occupied
habitat thought to be present in Montana in 1961.
In Wyoming, the black-tailed prairie dog historically occupied
habitat in the eastern half of the State, east of the Rocky Mountains
(Hall and Kelson 1959, p. 365). Currently, distribution is scattered in
remnant populations throughout at least 75 percent of the historical
range (Van Pelt 2009, p. 40). A 2006 study estimated the amount of
occupied habitat to be 229,607 ac (92,919 ha) (Grenier et al. 2007, p.
125) and these results suggested that black-tailed prairie dog
populations in Wyoming remain stable (Emmerich 2010, pers. comm.). This
represents nearly a five-fold increase over occupied habitat thought to
be present in Wyoming since in 1961.
In the past, the conversion of native prairie habitat or rangeland
to cropland reduced black-tailed prairie dog colonies, and thereby
impacted the mountain plover's most productive breeding habitat in the
grassland ecosystem. Conversion of native prairie to cropland
historically progressed across the Great Plains from east to west. The
most intensive farming activity remains in the east, in portions of
North Dakota, South Dakota, Nebraska, Kansas, Oklahoma, and Texas,
where higher rainfall amounts and generally better soils result in
greater agricultural production, and the land supports crops such as
corn and soybeans. This land conversion resulted in the historical
reduction in black-tailed prairie dog populations; as well as
reductions in mountain plover populations in Nebraska, Kansas,
Oklahoma, and Texas; it also resulted in the extirpation of the
mountain plover populations in North Dakota and South Dakota. Land with
the highest potential for traditional farming uses was converted many
years ago. The threat of future destruction of both prairie dog and
mountain plover habitat through cropland conversion is minimal, much
less than in the early days of agricultural development in the Great
Plains (see Loss of Breeding Habitat to Land Conversion and
Development, below).
The present or threatened alteration of habitat due to oil, gas,
coalbed methane, and mineral extraction, and wind energy development,
affects portions of black-tailed prairie dog occupied habitat; however,
we have no information regarding the extent of potential impacts.
Nevertheless, prairie dog occupancy has apparently increased within oil
and gas development areas in Wyoming (Sorensen et al. 2009, pp. 5-6).
We have no evidence that present or threatened curtailment of habitat
due to oil, gas, coalbed methane, and mineral extraction, and wind
energy development, is a limiting factor for the black-tailed prairie
dog in Wyoming or elsewhere throughout its range.
Approximately 110 million ac (45 million ha) of cropland and 283
million ac (115 million ha) of rangeland occur within the black-tailed
prairie dog's range at present (Ernst 2008, pp. 10-19). In our December
3, 2009, finding for the black-tailed prairie dog (74 FR 63343), we
contrasted the 2.4 million ac (1 million ha) of currently occupied
habitat with the 283 million ac (115 million ha) of rangeland and
concluded that sufficient potential habitat still occurs within the
range of the species in the United States to accommodate large
expansions of prairie dog populations (which in turn would benefit the
mountain plover) if the landowners and public sentiment allow. We
concluded that the present or threatened destruction, modification, or
curtailment of habitat or range is not a limiting factor for the black-
tailed prairie dog and that we do not anticipate that impacts from
habitat loss are likely to negatively impact the status of the species
in the foreseeable future. Because of the association between the
mountain plover and the black-tailed prairie dog, we believe that
appropriate habitat to support prairie dog colonies is not a limiting
factor within the breeding range of the mountain plover.
Sylvatic plague is an exotic disease foreign to the evolutionary
history of North American prairie dogs. It is caused by the bacterium
Yersinia pestis. Black-tailed prairie dogs are very sensitive to
sylvatic plague, and mortality in colonies affected frequently reaches
100 percent. Sylvatic plague has expanded its range to all States
within the range of the black-tailed prairie dog in recent years and
has caused local population declines at several sites. These declines
are typically followed by partial or complete recovery. Rangewide and
Statewide estimates of prairie dog occupied area did not include
unoccupied prairie dog colonies where sylvatic plague (or poisoning)
had at least temporarily eliminated prairie dogs. Over all prairie dog
colonies, unoccupied area was found to total 12 percent in Colorado, 15
percent in Montana, and 13 percent in Wyoming. The BLM mapped prairie
dog colonies
[[Page 27778]]
in Phillips County, Montana in 2004 and 2005, and returned to 50
randomly selected prairie dog colonies in 2010. Of the 50 colonies
selected for sampling, 48 were still active in 2010 (McDonald 2010). In
the changing mosaic, colonies lost or temporarily inactive may be
offset by colonies reoccupied or newly established.
We documented in our 12-month finding on a petition to list the
black-tailed prairie dog that, since the early 1960s, occupied black-
tailed prairie dog habitat has increased in every State, even in those
States where sylvatic plague has been present for over 50 years (74 FR
63355-63356). This increase has occurred despite continued impacts from
sylvatic plague and other threats. In our 2009 finding, we concluded
that the status of the black-tailed prairie dog, as indicated by
increased occupied habitat since the early 1960s, indicates that
sylvatic plague is not a limiting factor for the species (74 FR 63357).
Similarly, the increase in black-tailed prairie dog numbers in the
United States has occurred despite conflicting Federal and State
regulations and policies that encourage conservation of prairie dogs
through development of State and rangewide management plans, yet in
many cases continue to allow shooting and poisoning of prairie dogs.
Nevertheless, affected Federal and State agencies are engaged in black-
tailed prairie dog management and monitoring to a much greater extent
than they were 10 years ago.
Efforts to conserve the black-tailed prairie dog will likely be
beneficial to the mountain plover. Our December 3, 2009, finding for
the black-tailed prairie dog (74 FR 63343) described the 1998
establishment of the Black-tailed Prairie Dog Conservation Team, with
representatives from each State within the historical range of the
species, and the development of ``The Black-tailed Prairie Dog
Conservation Assessment and Strategy'' (Van Pelt 1999, entire), which
initiated development of ``A Multi-State Conservation Plan for the
Black-tailed Prairie Dog, Cynomys ludovicianus, in the United States''
(Multi-State Plan) (Luce 2002). The purpose of the Multi-State Plan was
to provide adaptive management goals for future prairie dog management
in the 11 States within the species' range. The plan identified 10-year
target objectives including maintaining and increasing occupied acreage
of black-tailed prairie dog habitat, and increasing the number of large
prairie dog complexes. The States also agreed to draft Statewide
management plans for the black-tailed prairie dog. The States approve
their own Statewide management plans. Colorado and Wyoming have
finalized grassland conservation plans that support and meet the
objectives of the Multi-State Plan. However, Montana is among the
States that have finalized management plans that do not support or meet
all of the objectives of the Multi-State Plan. These and other efforts
give promise that the trend of increasing black-tailed prairie dogs
populations since 1961 can be sustained.
Climate change will likely affect black-tailed prairie dogs and
their habitat; however, at this time we have no information on the
direct relationship between climate change and black-tailed prairie dog
population trends, and we cannot quantify the potential magnitude or
extent of impact that climate change may have on the species. While
climate change may potentially impact the species in future decades,
particularly through its effects on sylvatic plague, it is not apparent
that a net loss in occupied habitat will result. The current status of
the black-tailed prairie dog does not suggest that the combined effects
of sylvatic plague and climate change are currently limiting factors
for the species or that they will become so within the foreseeable
future, and we do not believe climate change will result in significant
population-level impacts to the black-tailed prairie dog.
In summary, we believe that the black-tailed prairie dog is a
resilient species and that overall United States populations are not
expected to be significantly affected by habitat loss due to conversion
to cropland, sylvatic plague, shooting, poisoning, or climate change
(74 FR 63364, December 3, 2009).
Mountain plover populations in Montana, and to a lesser extent
other breeding areas, are dependent on the prairie dog for breeding
habitat. Given our conclusion that habitat created or enhanced by
black-tailed prairie dogs is unlikely to decrease, we conclude that
threats to the black-tailed prairie dog in the United States do not
represent a threat to the continued existence of the mountain plover.
Potential dependence of both wintering and breeding mountain plover
populations on remaining prairie dog colonies in Mexico is of concern
(Macias-Duarte and Panjabi 2010, pp. 9-10). In Mexico, decline of
native grasslands supporting the black-tailed prairie dog and the
Federally endangered Mexican prairie dog have been extensive, despite
some environmental regulations designed to protect prairie dogs and
their habitats. The large black-tailed prairie dog complex at Janos has
been reduced by 73 percent since 1988, to approximately 38,000 ac
(16,000 ha), while Mexican prairie dog colonies within the El Tokio
region have also been reduced to approximately 79,000 ac (32,000 ha)
(Andres and Stone 2009, p. 28; Ceballos et al. 2010, pp, 7-8; Macias-
Duarte and Punjabi 2010, p. 9-10). Both areas, at least in some years,
support significant numbers of wintering mountain plover (see
Conservation Status and Local Populations above). Destruction and
fragmentation of prairie dog colonies has occurred through poisoning
and shooting of prairie dogs, conversion to cattle ranching or farming,
overgrazing, and drought. Mexico experienced a prolonged drought in the
Janos area in recent years, which resulted in dramatic loss of
vegetation, followed by a reduction in black-tailed prairie dog
occupied habitat (Larson 2008, p. 87).
These losses in prairie dog habitat in Mexico have degraded or
eliminated the extent of wintering plover habitat in these areas.
Recent efforts to protect prairie dogs and grasslands also benefit
wintering mountain plover and may help stop or reverse recent trends.
Government designation of protected areas in Chihuahua and Nuevo Leon,
and efforts by Pronatura Noreste, The Nature Conservancy, and other
institutions, hold promise (Andres and Stone 2009, pp. 33, 40; Macias-
Duarte and Punjabi 2010, p. 10). In 2009, the 1.3-million-ac (526,000-
ha) Janos Biosphere Reserve was established to protect some of the best
remaining shortgrass prairie in Mexico and thereby benefit the black-
tailed prairie dog. This conservation initiative is led by Mexico's
National Protected Areas Commission and the Chihuahuan State government
(The Nature Conservancy 2010). The Llano de la Soledad, which
encompasses the major Mexican prairie dog complexes of the El Tokio
area, a 26,000-ac (10,500-ha) area, has been designated a State Natural
Area for Ecological Conservation administered by the Agency of
Environmental Protection and Natural Resources of Nuevo Leon.
Neotropical migratory bird grants from the Service have supported
efforts led by Pronatura Noreste to protect and manage key lands
through purchase and easement. While past habitat loss for the mountain
plover at Janos and El Tokio has been significant, international
attention to these and to other important grassland complexes in Mexico
improves prospects for future conservation and maintenance of mountain
plover wintering habitat.
Knowledge of mountain plover breeding on prairie dog colonies in
Mexico is limited. The primary known
[[Page 27779]]
value of black-tailed and Mexican prairie dog colonies to the mountain
plover is as wintering habitat; yet use varies greatly from year to
year. Mountain plover use of croplands and rangelands present in Mexico
for wintering is largely unstudied. For example, agricultural areas in
northern Baja California, the coastal plains of Sonora and Sinaloa, and
throughout the northern Chihuahuan Desert States may potentially
support substantial wintering populations (Macias-Duarte and Punjabi
2010, p. 10). The net effect of reduction in prairie dog colonies in
Mexico to mountain plover is largely unknown. However, given that
mountain plover winter extensively in cropland habitats in California
and Texas, we believe that cropland habitats in Mexico are likely
available as alternative wintering habitat. There is no available
information to indicate that the past, current, or potential future
loss of black-tailed and Mexican prairie dog colonies and the
ecosystems they support in Mexico is a significant threat to the
mountain plover.
Despite the ongoing effects of habitat conversion, sylvatic plague,
shooting and poisoning, and lack of regulatory mechanisms that provide
protection, black-tailed prairie dog habitats have increased in the
United States over the last 50 years (74 FR 63343, December 3, 2009).
Although there is significant concern about the status of black-tailed
and Mexican prairie dogs and their habitats in Mexico, there is no
information available to indicate that further reductions in prairie
dogs in Mexico are threatening the mountain plover. At this time, the
best available scientific information does not indicate that the loss
of prairie dog habitat is likely to threaten the mountain plover now or
in the foreseeable future.
Loss of Breeding Habitat to Land Conversion and Development
As described above, losses of native grasslands in the Great Plains
have been severe since European settlement. Losses of these native
grasslands have been greatest in the eastern Great Plains and have
impacted the mountain plover mainly from conversion of prairie
grasslands to crop fields incompatible with mountain plover breeding,
including those planted to corn and soybeans. These losses are likely
the reason why the mountain plover no longer breeds in the Dakotas, has
a limited range in Nebraska, and is now a rare breeder in Kansas (Graul
and Webster 1976, p. 266; Knopf and Wunder 2006). Land conversion to
agriculture continues, primarily in the northern Great Plains, but at a
much slower rate. Over the 15-year period from 1982 to 1997, in
Montana, Wyoming, and Colorado, there were no decreases in the amount
of rangeland or pastureland present (USDA 2010). Conversion to cropland
may be locally affecting mountain plover in some areas of Montana.
Approximately 47,000 ac (19,000 ha) of native grassland was converted
to agriculture in Montana from 2005 to 2009 (Ducks Unlimited, cited in
McDonald 2010). Statewide, the amount of cropland in Montana increased
by about 3 percent from 1997 to 2007 (USDA 2010). In the four Montana
counties with the most mountain plover habitat (Blain, Fergus,
Phillips, and Valley Counties), cropland increased over the same period
by about 6 percent, with most of the increase attributable to Valley
County (USDA 2010). However, the cited conversion from 2005 to 2009
represents less than 0.2 percent of the 30 million ac (12 million ha)
of ``grassland/herbaceous'' cover present in Montana in 2001 (USGS
2001). Cropland is used by breeding mountain plover elsewhere, but its
potential for use in Montana is unknown. Conversion of grasslands to
cropland in Montana may locally impact mountain plover; however, we
believe this low rate of conversion would have negligible rangewide
effect.
The best information available does not allow us to estimate the
specific amount of occupied grassland breeding habitat for mountain
plover that has been converted to other uses in recent years. However,
given the apparent low rate of grassland conversion in Montana and
rangewide, and the mountain plover's ability to use grassland that has
been converted to other uses such as certain agricultural crops
including wheat, sorghum, and millet, we believe that grassland
conversion does not pose a substantial threat to the mountain plover in
Montana, or elsewhere in its breeding range, now or in the foreseeable
future.
In our 1999 and 2002 proposals to list the mountain plover as a
threatened species (64 FR 7587 and 67 FR 72396, respectively), we also
addressed the concern that grassland breeding habitat may be lost to
human development. Since the mountain plover's breeding range is
extensive, there are undoubtedly instances where human development is
and will locally displace the mountain plover. We agree with the
conclusion of Andres and Stone (2009, p. 22) that habitat in the
mountain plover breeding range is subject to little overall threat from
residential and commercial development, because human development is
not expected to be very extensive in the largely rural areas of the
species' breeding habitat.
An area that generated past concern in our 1999 and 2002 proposals
is South Park, Park County, Colorado, an approximately 480,000 ac
(200,000 ha) grassland basin where the mountain plover breeding
population is estimated to be about 2,300 birds. Much of the mountain
plover habitat in South Park is privately owned, and 32 percent of this
area has been subdivided (Granau and Wunder 2001, pp. 8-9). Substantial
build-out of those properties currently subdivided would be detrimental
to mountain plover; however, human population growth in South Park is
modest (Nichols 2010, pers. comm.). Many of the subdivisions occurred
in the 1960s and 1970s, and have not been developed. Earlier forecasts
suggested South Park would have a human population of 10,000 by 2010,
but the current human population stands at approximately 3,500 (Nichols
2010, pers. comm.). Issuance of building permits countywide have
decreased steadily in recent years, from 297 in 2002 to 70 in 2009
(Carrington 2010, pers. comm.). In addition, land protection and
conservation efforts by the BLM, Park County, Colorado Open Lands, and
The Nature Conservancy are ongoing in South Park. The BLM (2009a, p. 2)
amended their Royal Gorge Resource Area Management Plan for the South
Park Subregion in light of new resource goals, including the protection
of mountain plover breeding habitat. Their Land Tenure Designation Plan
for South Park was modified to keep a greater portion of the BLM's
approximately 63,000 ac (26,000 ha) of South Park lands in Federal
ownership and make less sensitive BLM lands available for exchange to
consolidate Federal lands of highest resource value. Primary goals of
Park County's Master Plan include protection of environmentally
sensitive areas, and managing the location and pace of residential
growth (Park County 2001, p. 13). In addition, Colorado Open Lands and
their partners have preserved approximately 17,000 ac (7,000 ha) of
lands in South Park to minimize development in and around significant
conservation areas (Colorado Open Lands 2011).
The current level of residential development in South Park is not
currently a threat to the mountain plover and, given recent development
trends and conservation initiatives, we do not consider residential
development in South Park to be a threat in the foreseeable future.
Elsewhere, threats from human development are largely limited to
wintering habitat.
[[Page 27780]]
In summary, we do not believe that conversion of the mountain
plover's grassland breeding habitat to cropland, or to human
residential and commercial development, represents a threat to the
mountain plover now or in the foreseeable future.
Range Management
Breeding mountain plover in grasslands are strongly associated with
heavy grazing and soil disturbance (Knopf and Wunder 2006). In the
absence of prairie dogs, activities such as heavy cattle grazing, the
concentration of cattle at loafing areas and at water, and burning of
rangeland provide habitat for mountain plover. However, typical range
management practices such as fencing, rotational grazing, decreased
stocking rates, and planting nonnative grasses to improve soil moisture
promote uniform vegetative cover and taller grasses, which are less
beneficial to breeding mountain plover. In addition, human efforts to
suppress wildfire are generally detrimental to mountain plover.
Specific range management options for mountain plover are somewhat
limited. Cattle grazing provides benefits to mountain plover, but this
is especially true when it maintains low vegetation and patches of bare
ground. Heavy cattle grazing may not be a financially justifiable
option for ranchers and can create conditions unfavorable to many other
species of wildlife. Aside from grazing, specific range management
options for mountain plover are somewhat limited. Mountain plover use
burned areas for breeding, and prescribed burning can be used as a
habitat management tool (Knopf 2008, p. 61; Andres and Stone 2009, p.
29). Ongoing USFS burning programs on the PNG and the Comanche National
Grasslands in Colorado to attract breeding mountain plover have had
some success (Augustine 2010a, pers. comm.). However, primary benefits
of burning a site are generally of short duration, i.e., 1 or 2 years
(Augustine 2010b, pers. comm.). The value of burning is dependent on
the extent and the frequency of burns. Augustine and Malchunas (2009,
p. 89) suggested that late winter shortgrass burns may have neutral or
positive consequences for livestock, but burning is not a management
practice generally employed within the mountain plover's breeding
range.
Even without rangeland management that specifically benefits the
mountain plover, soil type, site history, or drought may create habitat
conditions that are beneficial to breeding mountain plover. Rocky or
clay pan substrate may suppress vegetation and provide breeding habitat
(Knopf and Wunder 2006). In years of low precipitation, grazing at
relatively low intensity has a greater impact on grassland vegetation
and can produce habitat conditions favorable for mountain plover
breeding.
Knopf (2008, entire) provided an historical account of mountain
plover populations on the PNG, Weld County, Colorado, and discussed the
future of mountain plover in the area. He suggested that mountain
plover numbers in the area had been in decline since the post-dust bowl
days of the late 1930s and early 1940s, and that the dramatic decline
in the mid-1990s was the abrupt end point of a process of deteriorating
mountain plover habitat (recovery of grassland habitat), which was
exacerbated by other factors such as wet spring weather and predation
(Knopf 2008, p. 60). Given current range management practices, Knopf
suggested that short-term benefits from prescribed burning and, more
significantly, the maintenance of prairie dog colonies were the only
viable means to enhance mountain plover habitat on the PNG.
Sheep grazing can maintain the low vegetation structure that is
beneficial to breeding mountain plover. However, the current level of
sheep grazing does not maintain significant amounts of mountain plover
breeding habitat rangewide. The sheep industry in the United States has
been in decline for more than 60 years and now supports about one-tenth
of the number of sheep present in the 1940s. Decreases in sheep grazing
may have been a contributing factor to loss of favorable grassland
breeding habitat for the mountain plover in the past. The future of the
industry is uncertain; continued declines in the industry are likely in
some areas, but changes in the industry also present opportunities for
its growth (National Academy of Sciences 2008, p. 4). For the
foreseeable future, it appears likely that sheep grazing will remain a
minor rangewide contributor to maintenance of favorable mountain plover
breeding habitat, but that potential for any further decline in
breeding habitat due to additional loss of acreage grazed by sheep is
minimal.
A number of conservation efforts target the conservation of
grasslands, prairie ecosystems, and prairie birds: The Great Plains
Landscape Conservation Cooperative (a public/private initiative to
proactively conserve declining habitats on private lands); The Nature
Conservancy's ecoregional plan for the Central Shortgrass Prairie; the
Colorado Division of Wildlife's Conservation Plan for Grassland Species
and similar efforts in other States; Natural Resources Conservation
Service conservation efforts under the Farm Bill; preservation of
grasslands via conservation easements, including more than 350,000 ac
(140,000 ha) in easements reported by the Colorado Cattleman's
Agricultural Land Trust (2010); the Rocky Mountain Bird Observatory's
Prairie Partners; and The Nature Conservancy's ``Prairie Wings''
effort. Many of these initiatives include conservation of the mountain
plover, the black-tailed prairie dog, and other species supported by
the prairie dog ecosystem.
In summary, the extent to which mountain plover are benefitted by
cattle grazing on any given site is determined by the range management
practices employed. While some current management practices result in
habitat conditions that are not optimal for mountain plover breeding, a
large number of mountain plover nest on rangeland. We do not anticipate
future changes to the current pattern of range management across the
breeding range of the mountain plover that would prove detrimental to
the mountain plover and its habitat. The extent to which range
management practices could benefit the mountain plover in the future is
dependent on conservation of black-tailed prairie dog colonies and, to
a lesser extent, on willingness to employ prescribed burning as a range
management tool. Grazing by sheep can create favorable breeding habitat
for mountain plover. The sheep industry in the western United States
has declined over time, but we do not anticipate that future changes in
the sheep industry will have a net negative impact on existing mountain
plover habitat or be a threat to existing mountain plover habitat in
the future.
Cultivated Areas in the Mountain Plover Breeding Range Acting as a
Potential Population Sink
Agricultural practices can destroy mountain plover nests and eggs
from mechanical treatment (tilling, planting, application of
fertilizers and pesticides), and crops growing beyond a certain height
may cause nest abandonment (Knopf and Rupert 1999, p. 85; Dinsmore
2003, p. 27). In our 1999 and 2002 proposals to list the mountain
plover as a threatened species (64 FR 7587 and 67 FR 72396,
respectively), we raised the concern that these activities could create
a reproductive ``sink,'' or in other words a situation in which
mountain plover are drawn to crop fields for nesting but do not produce
viable young at a rate that would sustain the population.
[[Page 27781]]
Knopf and Rupert (1999, p. 84) suggested that breeding mountain
plover having the opportunity to nest on either agricultural or prairie
areas chose both equally. In the eastern Colorado shortgrass prairie
ecosystem, mountain plover breeding densities on crop fields were twice
as high as the densities found on grasslands without prairie dogs,
although only one-fifth as high as the densities found on prairie dog
colonies (Tipton et al. 2009, p. 496). Based on the area of habitats
surveyed and densities of mountain plover estimated, approximately 40
percent of mountain plover may use crop fields for nesting in eastern
Colorado. Nebraska studies (Van der Burg et al. 2010, pp. 48, 50)
suggested a similar percentage of the mountain plover in Nebraska
utilize crop fields for nesting. The small, seemingly stable, breeding
mountain plover population in Oklahoma was primarily found in plowed or
fallow fields, although again the potential of a reproductive sink was
raised (MacConnell et al. 2009, pp. 31-33). Based on estimates of
mountain plover using crop fields in Colorado and Nebraska, together
with known use of crop fields in Wyoming, Oklahoma, and Kansas, we
conclude that up to one quarter of all mountain plover may utilize crop
fields for breeding. Given the significance of crop fields to breeding
mountain plover and questions regarding a possible reproductive sink,
research is ongoing to better understand the role that crop fields play
in support of breeding mountain plover populations (Dreitz et al.
2010).
In Colorado, mountain plover hatching success was found to be
similar in native grasslands and crop fields, although causes of nest
mortality differed between the two habitats (Dreitz and Knopf 2007, pp.
684-685). Use of crop fields was not determined to be detrimental to
mountain plover hatching success. However, a subsequent eastern
Colorado study found chick survival to be similar on crop fields (23
percent) to shortgrass habitat without prairie dogs (24 percent), but
lower than chick survival on shortgrass habitat occupied by black-
tailed prairie dogs (75 percent), and the author again suggested that
crop fields may represent a reproductive sink or ``ecological trap''
(Dreitz 2009, pp. 875-877). Given the study results, the same concern
could be raised regarding shortgrass habitat lacking prairie dogs. In
contrast to the study above, recent research on crop fields in Nebraska
found 95 percent survival of chicks of adult mountain plover tracked
for 35 days (Blakesley and Jorgensen 2010, pers. comm.), although loss
of contact with other adult mountain plover suggests that actual chick
survival was somewhat lower (Blakesley 2010, pers. comm.). Preliminary
data from studies of radio-tracked chicks in Montana and Colorado in
2010 (Dreitz et al. 2010) did not show chick survival in crop fields to
be lower than in other habitats. While results reported by Dreitz
(2009, pp. 875-877) above come from the most comprehensive study of
chick survival in crop fields, other studies indicate that mountain
plover chick survival rates on crop fields and among other prairie
habitats vary greatly in time and place.
Shackford et al. (1999, p. 119) suggested that decreasing nest loss
from mechanical treatment of fields would benefit mountain plover. Nest
marking efforts that allow farmers to avoid nests and reduce nest
mortality from agricultural operations have been conducted with
cooperating farmers in Colorado and Nebraska (Dreitz and Knopf 2007, p.
685; Lock and VerCauteren 2008, entire; Bly 2010a). The Colorado
Division of Wildlife and the Nebraska Game and Parks Commission, along
with the Rocky Mountain Bird Observatory, initiated nest marking
programs. In Nebraska, a reported 80 percent of 246 nests marked in
crop fields over 3 years successfully hatched young (Bly 2010a). As a
comparison, an experiment using dummy nests suggested a 35 percent
success rate was likely in crop fields if nests were not marked (Bly
2010a).
While recent analysis of mountain plover populations suggests that
efforts targeting chick survival may hold more conservation value than
those efforts to enhance nest success, management techniques to achieve
higher chick survival may be difficult to employ. In addition, nest
marking programs have helped establish ties between the agricultural
community and wildlife managers (Dreitz and Knopf 2007, pp. 685-686;
VerCauteren 2010). Outreach efforts to farmers continue, including
education regarding mountain plover and transition from nest marking to
landowners' taking the lead in finding and avoiding mountain plover
nests in the course of their field operations. Community efforts, such
as the annual Mountain Plover Festival sponsored by the Karval
Community Alliance in Lincoln County, Colorado, promote stewardship of
the mountain plover and other wildlife as an integral part of both
farming and ranching practices.
Studies documenting numbers and reproductive success of mountain
plover breeding on crop fields in eastern Colorado and Nebraska do not
entirely resolve the issue of the relative value of this habitat to the
mountain plover. However, in studies from eastern Colorado, nest
success in crop fields (Dreitz and Knopf 2007, pp. 684-685) and chick
survival in crop fields (Dreitz 2009, pp. 875-877; Dreitz et al. 2010)
appear similar to nest success and chick survival in native shortgrass
without prairie dogs. We conclude that crop fields support breeding
mountain plover as well as shortgrass without prairie dogs, although
likely not as well as shortgrass with prairie dogs. If the crop fields
in eastern Colorado that are regularly occupied by breeding mountain
plover are a reproductive sink, their continued occupancy by mountain
plover is dependent on a net influx of birds dispersing from other
breeding habitats. We have no evidence to suggest whether or not this
is occurring. Further, unless mountain plover prefer and choose crop
fields for breeding over available (unoccupied) habitat where
reproductive success is higher, breeding in crop fields, even if less
successful, would not seem detrimental. We conclude that, based on the
information available, the mountain plover's use of crop fields for
breeding does not represent a threat to the species.
Another concern is the potential that change in current
agricultural practices will result in future loss of the types of crop
fields that currently provide breeding habitat for mountain plover.
Dryland agriculture is the type of agriculture that most frequently
supports breeding mountain plover, and it is dominated by wheat, but
also includes crops of sorghum, millet, and sunflowers. Annual
variation in the use of dryland agriculture fields is dictated by a
number of factors including weather, government programs, crop prices,
and preferences of individual farmers. It is not known whether any
significant future changes to dryland agriculture that the mountain
plover uses for breeding are likely to occur or how they would affect
mountain plover (Andres and Stone 2009, p. 23).
In recent years, ethanol production from corn has expanded in the
United States; however, most corn is cultivated east of the range of
the mountain plover (Westcott 2007, pp. 1-3). Additionally, the
increase in corn production largely occurs by adjusting crop rotations
between corn and soybeans (Westcott 2007, p. 7); neither crop regularly
supports mountain plover. We do not anticipate that increased ethanol
production will result in a substantial loss in the species' occupied
or potential habitat because the majority of this activity lies outside
the range of the mountain plover.
[[Page 27782]]
In conclusion, we believe that approximately one quarter of the
rangewide mountain plover population breeds in crop fields in Colorado,
Nebraska, or elsewhere, but there is no evidence that this represents a
reproductive sink detrimental to the rangewide population. Dryland
agriculture has changed little over recent decades, and we have little
evidence to suggest that crop fields now, or in the future, represent a
significant threat to the mountain plover.
Energy and Mineral Development
Development targeting oil and gas, coal bed methane, wind energy,
and other mineral resources is extensive within the breeding range of
the mountain plover. Energy development is a national priority as
mandated by Executive Orders 13212 (Actions to Expedite Energy-Related
Projects) (66 FR 28357, May 22, 2001) and 13514 (Federal Leadership in
Environmental, Energy, and Economic Performance) (74 FR 52117, October
8, 2009), and the Energy Independence and Security Act of 2007 (42
U.S.C. 17001 et seq.). Current permitting and construction of new
energy projects on Federal and non-Federal lands reflects this
priority. The development of energy resources requires construction at
well or wind turbine sites, as well as access roads, pipelines, power
lines, and other support facilities. These projects could have an
immediate effect on breeding mountain plover due to disturbance and
habitat conversion, and secondary effects associated with operation and
maintenance.
The magnitude of the issue is best exemplified by energy
development in Wyoming, where the Wyoming Natural Diversity Database
(WYNDD) (2010) has used habitat mapping and mountain plover observation
records to map the probability of mountain plover presence. In Wyoming,
WYNDD (2010) predicts a high probability of mountain plover occurrence
over about 7 million ac (3 million ha) and a medium probability of
occurrence over about 14 million ac (6 million ha). We evaluated
overlap between predicted mountain plover presence and energy
development (Lindstom 2010).
As of February 2010, 5,043 wells, approximately 12 percent of
operating oil and gas wells in Wyoming (Wyoming Oil and Gas Commission
2010), occurred in areas of high probability of mountain plover
occurrence, while 13,266 wells, about 32 percent of wells, occurred in
areas with medium probability of mountain plover occurrence. While
wells are clustered in well fields, this would equate to one well per
about 1,400 ac (560 ha) in areas of high probability of mountain plover
occurrence and one well per 1,080 ac (430 ha) in areas medium
probability of occurrence. We believe that this represents a relatively
low overall potential impact to mountain plover habitat.
Of 13 million ac (6 million ha) of authorized (both developed and
undeveloped) BLM oil and gas leases in Wyoming (BLM 2009b), we
estimated that 52 percent were in areas of high or medium probability
of mountain plover occurrence (or about one-third of all areas of high
or medium probability of mountain plover occurrence were under BLM
lease).
Areas in Wyoming of wind classes 4 through 7 (a measure of wind
resource potential) account for about 6 million ac (2.4 million ha), or
about 30 percent, of those areas of high or medium probability of
mountain plover occurrence (National Renewable Energy Laboratory 2002).
Since additional factors determine development potential, only a
portion of these areas would likely see future wind energy development.
Future energy development will depend on whether oil and gas
resources are actually present, the location of wind resources relative
to consumers, future demand, economic considerations, and environmental
regulations. Therefore, it is uncertain to what degree energy projects
will be developed in mountain plover breeding habitat in Wyoming, or
other portions of the range, in the foreseeable future. However, given
our evaluation above, we believe that current and future energy
development in mountain plover habitat may be substantial in Wyoming.
Existing and proposed oil and gas development and wind energy projects
also occur in mountain plover habitat in Montana and the plains of
Colorado, as well as in other States within the mountain plover's
breeding, migratory, and wintering range. The cumulative total of
current and future energy development elsewhere in the mountain
plover's breeding range may not approach that likely to occur in
Wyoming, but energy development is likely to occur within many breeding
areas used by the species. For example, oil and gas development
continues in Weld County, Colorado, and renewed exploration is
occurring on and near the PNG (Philbrook 2010, pers. comm.), formerly
an important breeding area for the mountain plover.
Concerns over impacts of oil and gas development to landscapes and
to various wildlife species have prompted environmental review
standards (BLM 2010c), and may lead to more widespread use of
development practices that minimize impacts. For example, directional
drilling, where feasible, has the potential to decrease habitat
impacts. Increased piping, product storage in central locations, and
remote sensing of wells may reduce vehicular traffic and the impact of
roads.
Despite the prevalence of energy development activities throughout
the range of the mountain plover, there is little evidence as to
whether, or to what extent, the overall effects of energy development
are detrimental to mountain plover (Andres and Stone 2009, p. 25).
Although oil and gas field development modifies and fragments nesting,
brood rearing, and foraging habitats, mountain plover continue to use
these areas (Smith and Keinath 2004, p. 36; Carr, in review). For many
wildlife species, the principal impact of energy development is
fragmentation rather than habitat loss. Energy development, even when
extensive, may directly impact only a small percentage of an area. In a
study of the Big Piney-LaBarge oil and gas field in the Upper Green
River Valley of Wyoming, where well density averaged about one well per
64 ac (26 ha), 97 percent of the landscape was within 0.25 mile (0.40
kilometer) of infrastructure (roads, pipelines, well pads, waste pits),
but only 4 percent of the area was directly impacted by oil and gas
infrastructure (Morton et al. 2004, pp. 10-11). Carr (in review) found
that mountain plover located nests in relation to habitat available,
rather than avoiding locations of energy development. We have no data
to suggest that the mountain plover is impacted by habitat
fragmentation, as opposed to habitat loss.
Because the mountain plover generally favors disturbance that
reduces vegetative cover and exposes bare ground (e.g., prairie dogs,
grazing, fire), it may tolerate surface disturbance from energy
development (Andres and Stone 2009, p. 25; Carr, in review). In Utah,
disturbed areas around oil well pads reportedly created open habitat
with bare ground suitable for the mountain plover (Day 1994, pp. 298-
299). Manning and White (2001, p. 226) found all mountain plover nests
in Utah to be situated near roadways or oil well pads, and saw adults
and chicks using these areas for foraging both day and night. However,
they suggested that while mountain plover tended to choose nest sites
near surface disturbance, the overall impact of oil and gas expansion
could be negative (Manning and White 2001, p. 226). This small,
apparently isolated Utah population subsequently
[[Page 27783]]
declined, and no birds have been found during surveys of the area since
2003 (Maxfield 2010, pers. comm.). Decline of the population occurred
subsequent to oil and gas development, but no direct tie was
established. Severe drought and cessation of sheep grazing that
provided mountain plover breeding habitat may have been more
significant to the apparent loss of this local population (Maxfield
2010, pers. comm.).
Carr (in review) provides the only targeted study of mountain
plover response to oil and gas development. The USGS study evaluated
the effects of oil and gas development on mountain plover population
density and nesting success in mixed desert shrublands in Wyoming.
Results suggested that the presence of wells, roads, and associated
infrastructure at densities studied (up to 8 wells per square mile (3
per square kilometer)) did not have detectable negative effects on
breeding mountain plover (Carr, in review). Carr (in review) concluded
that energy development at low to moderate levels may be compatible
with nesting mountain plover, although the author suggested the need
for additional studies of potential effects of energy development on
chick survival and potential for impacts at higher well densities.
Tolerance to disturbance from energy development by mountain plover
could result in nesting or foraging in areas where continued human
disturbance and vehicular traffic could pose threats to adults and
chicks. Carr (in review) cautioned that human activities at well sites
might keep mountain plover from their nests, subjecting eggs to
possible overheating. In Oklahoma, mountain plover appeared unaffected
by the presence of roads (MacConnell et al. 2009, p. 33). Manning and
White (2001, p. 226) indicated that vehicular traffic did not influence
incubation or foraging behavior, and, while vehicular collisions with
mountain plover might be a concern, no such mortalities were noted.
Andres and Stone (2009, pp. 26, 27) noted that mountain plover are
tolerant of vehicles, and while there is potential that vehicles could
kill adult or juvenile birds, such mortality would not likely have a
population-level impact. In addition, collisions with stationary
structures such as power lines have been discounted as not likely a
significant cause of mortality (Knopf and Wunder 2006; Andres and Stone
2009, p. 26).
Other impacts of energy development on the mountain plover and its
habitat could occur. These include a potential for increase in
predators, increased opportunity for spread of invasive plants, and
potential changes in human land use such as cessation of grazing.
Despite these concerns, to date, impacts of oil and gas development at
levels typically seen in mountain plover breeding habitat have not been
shown to decrease mountain plover populations.
Coalbed methane extraction is a process in which: (1) Wells are
drilled into the coal seam; (2) the seam is dewatered; and (3) the
methane is then extracted from the seam, compressed, and piped to
market. In Wyoming, some water from coalbed methane operations is used
for surface or subsurface irrigation of agriculture fields and
rangeland. There is concern that plover habitat, including prairie dog
colonies, have been and could be lost to these practices, thereby
altering or eliminating important mountain plover habitat (Rogers 2010,
pers. comm.). In the Powder River Basin, about 2,000 ac (800 ha) of
such irrigation is occurring and more than 7,000 ac (3,000 ha) is
permitted (Fischer 2010, pers. comm.). We have no information as to
whether or not mountain plover have been displaced. While changes in
habitat caused by this irrigation may alter habitat and cause a local
impact to mountain plover, we do not believe that the relatively small
area involved represents a threat to overall mountain plover
populations in this region.
Like oil and gas development, wind energy development presents a
range of habitat changes and disturbance factors that could affect the
mountain plover. In addition, there is concern that the mountain
plover's use of areas may decline during and after construction due to
avoidance of wind turbines or increased mortality attributable to
collisions, primarily with moving rotor blades. Lock (2010) highlighted
the potential for wind energy projects to displace breeding mountain
plover, but described the potential threat of mortality from collisions
as being of ``low certainty.''
The most comprehensive study conducted on potential effects of wind
power development on the mountain plover came from the facility on
Foote Creek Rim in Carbon County, Wyoming, where mountain plover were
studied from 1994 (prior to construction) through 2007 (Young et al.
2007, entire). The authors suggested that mountain plover habituated
over time to the presence of turbines, as evidenced by nesting within
60 feet (ft) (20 meters (m)) of the base of a tower in one instance
(Young et al. 2007, p. 18).
Wind towers, rotors, and associated meteorological towers pose an
added risk that mountain plover may be struck by blades or fly into
stationary structures. However, carcass searches at Foote Creek Rim
documented no mountain plover mortalities attributable to collisions
over the 3 years the studies were conducted. On breeding grounds,
mountain plover fly at low heights. In a common courtship display, a
male flies only to a height of approximately 16 to 33 ft (5 to 10 m)
(Knopf and Wunder 2006). The lowest point of rotor sweep on the Foote
Creek Rim site (57 ft (17 m)) was above the typical heights flown by
mountain plover during courtship and breeding (Young et al. 2007, p.
18). Research at the Judith Gap Wind Farm in Montana found no evidence
of mountain plover displacement or fatalities (MacDonald 2010).
However, recently we became aware of two mountain plover mortalities
from searches of Wyoming wind energy projects (Sweanor 2010, pers.
comm.). Because sources of mortality could not be confirmed for either
carcass, we do not know whether the birds were struck by rotor blades,
collided with towers, or died from other causes. Rotor sweep was 126 ft
(41 m) above the ground in both cases, well above heights that breeding
mountain plover are thought to regularly fly. At Glenrock Rolling
Hills, one of the two sites reporting a mortality, no mountain plover
were observed prior to construction of the wind energy project, but
nesting occurred after construction, suggesting that nesting habitat
may have been created through project disturbance (Sweanor 2010, pers.
comm.).
Wind energy development could present a greater potential issue for
post-breeding congregations of mountain plover, because hundreds of
birds may flock in a single area. However, we have no information
regarding behavior of post-breeding flocks that could be applied to the
potential threat of bird strikes from wind turbines. Little is known
regarding their potential to strike moving blades or stationary
structures, although based on mortality studies, shorebirds (plovers,
sandpipers, and similar species) do not seem to be at great risk of
colliding with turbines or communication towers (Kerlinger 2011, pers.
comm.). Wind energy projects have reportedly been constructed and are
proposed in South Texas agricultural fields that may overlap with areas
used by wintering mountain plover (Cobb 2010, pers. comm.). The
potential for mountain plover displacement or collisions in Texas is
unknown. In California, wind energy development projects tend to be
located on mountain ridges where wind speeds are greater and,
therefore, are less likely to impact wintering mountain plover.
[[Page 27784]]
One exception is in Antelope Valley, Kern County (California), an area
where mountain plover are known to winter. Several wind energy projects
have been permitted on a mosaic of desert and agricultural lands.
Overall, evidence available does not suggest that wind energy
development is likely to displace mountain plover from breeding or
wintering areas, or cause direct mortality through collisions to the
extent that it would pose a threat to the species.
Surface mining for coal and other minerals can displace mountain
plover within the footprint of the work for the duration of the active
mining. Whether or not this would result in permanent displacement is
dependent on whether and how restoration occurs. We have little site-
specific data on impacts of surface mining to nearby mountain plover.
Surveys over 28 years at Cloud Peak Energy's Antelope Mine in Campbell
and Converse Counties, Wyoming, documented mountain plover's use of the
mine permit area and adjacent lands (Green 2010). Mountain plover
numbers declined as mining and the footprint of surface disturbance
progressed, but in general they showed tolerance to mining activities
nearby (Green 2010). In 2010, adult mountain plover and chicks were,
for the first time, seen using a reclaimed mine area at the Antelope
Mine (Green 2010). Mountain plover can be directly affected by surface
mining through temporary or permanent loss of their habitat. However,
we do not believe that surface mining, currently or in the future, will
impact a significant amount of the mountain plover's breeding range or
represent a threat to the species.
The BLM considers the mountain plover, among other species, when
evaluating the impacts of energy development on the environment. The
BLM, through its Special Status Species program, has developed various
management scenarios for the protection of the mountain plover
throughout its range. In 2005, the BLM analyzed the potential effects
to the mountain plover from management actions approved in Resource
Management Plans for the various BLM field offices in Wyoming (BLM
2005). At the time, we concluded that BLM's proactive conservation
measures should aid in protecting the species from further decline
(Kelly 2007). The conservation measures committed to by the BLM
included habitat screening (determining whether habitat might support
the mountain plover) and, as appropriate, subsequent surveys for the
possible presence of mountain plover prior to approval of ground-
disturbing activities; designation of a 0.25-mi (0.40-km) buffer around
occupied nests during the nesting season, with restrictions on
activities to protect nesting plover; and continued research and census
activities targeting the mountain plover on BLM-administered land in
Wyoming (BLM 2005). A number of best management practices were also
provided, to be considered on a case-by-case basis, to help protect the
mountain plover and expand suitable nesting habitat. While these
measures are not binding, and on-the-ground conservation efforts likely
vary by BLM field office, a proactive cooperative approach between the
BLM and the Service in Wyoming has heightened recognition of mountain
plover conservation on BLM-administered lands and provides a basis for
future cooperation to safeguard the species.
Solar energy projects are likely to displace mountain plover when
situated in breeding or wintering habitat. Unlike oil and gas wells or
wind turbines, solar collectors are placed so close together that they
effectively eliminate the ability of mountain plover to use the
habitat. Solar energy development potential is greatest in southwestern
States and California and, except for Colorado's San Luis Valley and
Northern New Mexico, occurs in areas used mostly by wintering rather
than breeding mountain plover. See Changes in Land Use in Mountain
Plover Wintering Range below for a discussion of solar energy
development.
In summary, potential effects to the mountain plover from energy
and mineral development are largely uncertain. Ground disturbance from
oil and gas development and wind energy development may, in some cases,
enhance or create mountain plover habitat, but whether the net effect
of such activity is beneficial or detrimental has not been determined.
The risk of significant mortality through mountain plover being struck
by rotors of wind turbines appears low. Whether, or to what extent,
construction of wind energy projects displaces breeding or wintering
mountain plover has not been clearly established. Surface mining
displaces mountain plover, at least until an area is restored, and
development of solar fields likely results in habitat loss. Overall,
more information regarding possible impacts of energy and mineral
development to mountain plover is needed. However, the information
currently available does not indicate that energy and mineral
development threatens the mountain plover now or is likely to do so
within the foreseeable future.
Changes in Land Use in Mountain Plover Wintering Range
In our December 5, 2002, proposal to list the mountain plover (67
FR 72396), we emphasized the potential impact to mountain plover
populations from changes to wintering habitat in California, including
changes stemming from human population growth, changes in agriculture,
water availability, and burning restrictions. It now appears that the
proportion of the rangewide population of mountain plover that winter
in California is far less than previously believed (see Conservation
Status and Local Populations above). However, the importance of
mountain plover wintering habitat in California has been a continued
topic of investigation and interest (Kopft and Rupert 1995; Hunting et
al. 2001; Wunder and Knopf 2003; Hunting and Edson 2008). Knopf and
Rupert (1995, p. 750) cited a high overwinter survival rate of mountain
plover in California and their use of agricultural fields, and
concluded that long-term population declines were likely attributable
to processes on their breeding grounds. Dinsmore et al. (2010)
concluded that adult survival in winter was high and suggested that
conservation and management efforts be directed toward chick survival
on breeding grounds and habitat during migration. In contrast, Hunting
and Edson (2008, p. 184) attributed both past declines and potential
future declines in rangewide plover populations to loss of traditional
wintering sites in California. Andres and Stone (2009, pp. 21, 22)
stated that effects to the mountain plover from changes to wintering
habitat in California's Central Valley were unknown, but also expressed
concerns regarding maintenance of quality wintering habitat in the
Imperial Valley, where a majority of mountain plover in California are
now thought to winter. Below we address current trends and potential
changes to the future extent and quality of mountain plover wintering
habitat in California.
Concern continues to center on land use trends, conversion of
agricultural lands to other uses, and changes in agriculture (Andres
and Stone 2009, pp. 22-24; Hunting and Edson 2008, p. 184). Due to
population growth in California, more rural and agricultural land is
being urbanized. Between 1982 and 2007, approximately 8 percent of
California's croplands, 11 percent of the State's pasturelands, and 6
percent of State's rangelands were lost (USDA 2010). However, as of
2007, California still supported approximately 9.5 million ac (3.8
million ha) of cropland,
[[Page 27785]]
1.1 million ac (0.4 million ha) of pastureland, and 17.5 million ac
(7.0 million ha) of rangeland (USDA 2010).
The dynamic, market-driven nature of agricultural production and
changes in cultivation practices in California could affect the
availability and quality of wintering habitat for the mountain plover.
Another issue is the dependence of California agriculture on irrigation
water, some of which is imported from other areas, and its future
availability. Future changes in the availability of irrigation water
might result from competition with other water uses, the effects of
global climate change (see discussion under Factor E below), and
changes in the characteristics of agricultural lands as a result of
improved or more broadly implemented water conservation techniques.
Development of energy projects, especially solar energy, in
mountain plover wintering habitat is also a concern in California.
California's electric utility companies were required by California
statute (Chapter 464, Statutes of 2006) to use renewable energy to
produce 20 percent of their power by 2010. Governor Schwarzenegger's
Executive Order of November 2008 (S-13-08) set a higher, more
ambitious goal of 33 percent by 2020 (California Energy Commission
2010). On April 12, 2011, Governor Jerry Brown signed Senate Bill 2X
into law, requiring that 33 percent of the State's electric generation
come from renewable sources by 2020 (Los Angeles Times 2011). A main
source of renewable power will be solar energy. A Statewide list of
solar energy projects includes over 400 proposals (Brickley 2011, pers.
comm.). Many large solar energy projects are being proposed on BLM
land, often in desert areas. The BLM, along with the Department of
Energy (DOE), is currently in the process of developing a Programmatic
Environmental Impact Statement (PEIS) for solar energy development in
six southwestern States, including California. The document assesses
development of a new solar energy program for siting utility-scale
solar energy projects on BLM lands. Any program adopted will have
implications for solar energy project siting in mountain plover
wintering habitat. A draft of the PEIS was made available for public
comment December 17, 2010 (75 FR 78980). Mountain plover are not
specifically addressed in the PEIS, but potential impacts to wildlife
and appropriate mitigation measures are provided (DOE 2010, pp. 5-73 to
5-96).
As described in Conservation Status and Local Populations above,
the California winter range of the mountain plover is primarily in the
Central Valley (including the Sacramento and San Joaquin valleys) and
the Imperial Valley. The Carrizo Plain in San Luis Obispo County is
also recognized as an important wintering site. Other areas where
mountain plover are regularly observed include the Panoche and Antelope
valleys.
The Central Valley (Sacramento Valley and San Joaquin Valley), Carrizo
Plain, Panoche Valley, and Antelope Valley
In the Central Valley, human population growth over the last 20
years has resulted in a declining trend in agricultural area, with a
smaller, but corresponding, trend of conversion to urban uses
(California Department of Conservation (CDC) 2010). The rate of land
conversion to urban uses in the Central Valley increased beginning in
1990. With the exception of Solano County, the human populations of
Central Valley counties within the wintering range of the mountain
plover all grew faster than the Statewide average between 2000 and 2009
(U.S. Census Bureau 2010).
In the Sacramento Valley, urbanization in Yolo and Solano Counties,
the two principal counties supporting wintering mountain plover, has
not adversely impacted the mountain plover to date, because known
wintering locations are located outside city planning boundaries.
However, continued population growth beyond the current planning
horizon could potentially threaten individual wintering localities that
are close to urban areas, particularly those in areas most proximate to
Sacramento.
In the San Joaquin Valley, human population growth has been
approximately 17 percent over the period from 1997 through 2010. To
date, most of the resulting urban growth has occurred adjacent to, and
in the general vicinity of, the towns, such as Modesto, Fresno, and
Bakersfield, that developed along Highway 99 in the eastern portion of
the San Joaquin Valley (Teitz et al. 2005, p. 27). These urban areas
are located to the east and outside of the mountain plover's wintering
range. To date, urbanization in the western San Joaquin Valley is
restricted to the Interstate 5 corridor, which supports few mountain
plover. Therefore, we expect it to have little effect on wintering
mountain plover. Scenarios developed to gauge effects of future
population growth and urbanization suggest that the San Joaquin Valley
will experience significant urban growth within the next 35 years;
increasing populations will result in scattered urbanization within the
plover's wintering range, but the pattern of development will depend on
land use planning goals, and potential development of high speed rail
(Teitz et al. 2005, pp. 45-67).
In the San Joaquin Valley counties (Fresno, Kern, Kings, Madera,
Merced, San Joaquin, Stanislaus, Tulare), cropland declined by about 3
percent from 1997 to 2007, to about 5.2 million ac (2.1 million ha)
(USDA 2010). Crop fields in alfalfa and other hay, favored by mountain
plover, were relatively stable and accounted for about one-third of all
cropland in the San Joaquin Valley in 2007 (USDA 2010).
While relatively little agricultural land is being lost, conversion
from annual agricultural crops to permanent crops that do not provide
mountain plover with habitat is significant within the San Joaquin
Valley. For example, in the San Luis Unit of the Central Valley Project
(CVP), in Fresno, Kings, and Merced Counties, agricultural acreage has
increasingly been converted to permanent crops of orchards or
vineyards. We estimate the percentage of land in permanent crops at
somewhere between 16 percent and 24 percent of the San Luis Unit,
compared with 10 percent in 2000. General field observations and land
value reports (California Society of Farm Managers and Rural Appraisers
2009, pp. 31-64) suggest that this is a continuing trend, with new
orchards displacing cotton and tomato crops in many areas of the
Central Valley. In Madera County, some locations formerly utilized by
wintering mountain plover have been converted from rangeland to annual
crops or to permanent crops such as pistachio trees (Woods 2009, pers.
comm.).
Outside of the Central Valley, orchard land in San Luis Obispo
County, which includes the Carrizo Plain, a known mountain plover
wintering area, rose from 29,000 ac (12,000 ha) to 54,000 ac (22,000
ha) from 2007 to 2009, to about 18 percent of cropland in the county.
Conversion to orchard crops in the nearby Maricopa and Cuyama valleys
near the Carrizo Plain area have resulted in loss of wintering mountain
plover habitat (Sharum 2010). Overall, conversion of annual cropping
systems to permanent crops is expected to continue and poses an
additional, but unquantified, source of habitat loss for the mountain
plover.
As a result of the large-scale irrigation efforts in the western
San Joaquin Valley, approximately 1,750,000 ac (710,000 ha) of
agricultural lands with shallow groundwater tables have become impaired
due to accumulated concentrations of naturally occurring toxic
elements, including selenium.
[[Page 27786]]
With the passage of the Central Valley Project Improvement Act (CVPIA)
in 1992, Federal and State acquisition programs enabled owners to stop
farming, or ``retire'' their privately owned, drainage-impaired
agricultural lands as a strategy to reduce drainage problems and
address selenium accumulations (Service 1998; USDI 2005). Lands
targeted for retirement lie primarily within the San Luis Unit of the
CVP along the west side of the San Joaquin Valley where approximately
379,000 ac (152,000 ha) of agricultural land have been identified as
contributing to poor water quality. Of these lands, nearly 200,000 ac
(80,000 ha) have been proposed for land retirement (USBR 2007), and, to
date, more than 100,000 ac (40,000 ha) of agricultural land have been
retired within the San Luis Unit. We have no estimate of what
proportion of this area may have supported acceptable wintering habitat
for the mountain plover or the extent to which it was used by the
mountain plover.
A portion of the lands proposed for retirement are expected to be
used for drainage reclamation; between 1,280 and 3,300 ac (5,170 and
1,340 ha) of existing irrigated cropland will be converted to treatment
facilities and evaporation basins, while 12,500 ac (5,100 ha) of either
existing or fallowed cropland will be converted to reuse areas in which
crops will be irrigated with selenium-contaminated, agricultural
drainwater in order to reduce selenium loads in the agricultural run-
off (Service 2006). These areas might threaten some mountain plover
with selenium toxicity, as described below in the discussion under
Factor E. Numerous retired parcels are characterized by dense weedy
growth (Cypher et al. 2007, p. 28; Service 2006), and are not expected
to provide suitable habitat for the plover. Substantial retired acreage
has been converted to permanent crops utilizing alternate sources of
water. Other retired lands that support grazing or farming may remain
suitable for wintering mountain plover.
Due to the historical importance of agriculture in the Central
Valley, the valley has the highest percentage of privately owned land
in the State. Only 4 percent of Sacramento Valley land and 7 percent of
San Joaquin Valley land is public open space. In the Central Valley, a
variety of conservation and restoration projects have been implemented
to protect natural resources, although 57 percent of such conservation
projects report a focus on riparian habitat enhancement (Great Valley
Center 2005, p. 30). Twenty-three local and regional land trusts
operate in the Central Valley to protect valley wildlife, farmland,
habitat, rivers, and native vegetation (Great Valley Center 2005, pp.
30-31). The Service does not have information on the area of specific
habitat types that have been protected within the range of the mountain
plover or whether these efforts have produced substantial benefits to
the species.
In the Sacramento Valley, we have found no planned solar energy
development likely to threaten the mountain plover's habitat. However,
the legislation cited above (Chapter 464, Statutes of 2006, and
Governor Schwarzenegger's Executive Order of November 2008 (S-
13-08)) has initiated a significant increase in the planning for solar
development in and adjacent to the San Joaquin Valley. Solar
developments proposed thus far vary greatly in size: small projects of
100 to 200 ac (40 to 80 ha), to projects of potentially to 30,000 ac
(12,000 ha) in size. The Service does not have specific information on
mountain plover use of many of these sites, but we conclude that sites
will be unsuitable for mountain plover after development.
To date, small projects are proposed for scattered locations across
the southern San Joaquin Valley, while large projects have been
proposed both within the San Joaquin Valley, and in the Carrizo Plain
and Panoche Valley areas. The solar projects proposed on the valley
floor are typically situated on active or recently cultivated
agricultural lands and several larger projects have been proposed for
lands that have been used for livestock grazing.
The Service is currently aware of up to six small solar projects,
each approximately 200 ac (80 ha) in size, which are expected within
the mountain plover's general wintering range in the southern San
Joaquin Valley. The projects will be constructed by Pacific Gas and
Electric, a major California utility company. In the San Joaquin
Valley, the solar projects proposed on the valley floor are typically
situated on active or recently cultivated agricultural lands and
several larger projects have been proposed for lands that have been
used for livestock grazing. The Service concludes that sites will be
unsuitable for mountain plover after development.
Several large proposals are located within the mountain plover's
general wintering range. A large 32,000-ac (13,000-ha) park, the
Westlands Solar Park, has been proposed for western Fresno and Kings
Counties, with an initial phase of approximately 10,000 ac (4,000 ha).
It will be constructed on agricultural land that the Westlands Water
District has slated for land retirement (Woody 2010). We expect that
additional proposals for retired farmland are likely due to the general
perception that such lands have few environmental issues.
The Maricopa Sun Solar Complex (approximately 9,000 ac (3,600 ha))
is proposed for agricultural lands in western Kern County near the edge
of the plover's winter range. We do not know whether the mountain
plover uses the site. Development of the project includes cancellation
of a contract to preserve agricultural land. The Draft Environmental
Impact Report identifies mountain plover as a potential winter migrant
(Kern County Planning and Community Development Department 2010, pp. 1,
4.4-8).
In the Carrizo Plain, San Luis Obispo County, two solar projects
have been proposed, including the 4,000-ac (1,619-ha) California Valley
Solar Ranch (CVSR) and the 4,500-ac (1,800-ha) Topaz Solar Farm. Both
facilities would be located approximately 6 miles north of the Carrizo
Plains National Monument, an important natural area for the plover, on
a mixture of natural lands, grazing lands, and cropped lands (Aspen
Environmental Group 2010, pp. C3-2-C3-3, C6-4). Suitable foraging and
roosting habitat for the mountain plover occurs on sites under
consideration (Aspen Environmental Group 2010, pp. C6-4-C6-5, C6-11).
Mountain plover have been observed on the CVSR site but likely occur
sporadically and in low numbers (Boroski 2011, pers. comm.).
The Panoche Valley, an area of about 12,000 ac (5,000 ha) in San
Benito County, receives annual use by wintering mountain plovers. A
solar project is currently proposed on 3,200 ac (1,300 ha) of potential
mountain plover wintering habitat, or about one-third of the potential
mountain plover habitat present in the Panoche Valley. Proposed
mitigation would preserve and manage other nearby habitat.
The Antelope Valley, an area of approximately 900,000 ac (360,000
ha) in Los Angeles and Kern Counties, supports wintering mountain
plover annually, with numbers estimated in the low 100s using crop
fields and grasslands (eBird 2010). How much of the valley's area is
mountain plover habitat is unclear. The valley is primarily privately
owned land, and its proximity to human population centers has generated
high interest in renewable energy (solar and wind) development that
could reduce mountain plover wintering habitat.
Solar energy projects currently planned in the San Joaquin Valley,
the
[[Page 27787]]
adjacent Carrizo Plain, and the Panoche and Antelope valleys are
likely, over time, to reduce existing mountain plover wintering
habitat. A variety of siting considerations, including presence of
other wildlife species of concern, and potential mitigation
requirements, will dictate the extent to which mountain plover are
affected. The Sacramento Valley and Imperial Valley lands used by the
mountain plover are less likely to be developed for solar projects. We
know of no solar projects are currently planned for agricultural lands
known to support mountain plover in the Imperial Valley, discussed
below.
As future solar projects are proposed and implemented, we conclude
that they will cause some continued loss of mountain plover wintering
habitat in California. While cumulative impacts of these projects, and
other factors such as urbanization and changes in agriculture, are
likely to reduce the total area of wintering habitat available,
substantial acreage of appropriate wintering habitat will persist in
the Central Valley, Carrizo Plain, Panoche Valley, and Antelope Valley.
The Imperial Valley
As of 2009, about 381,000 ac (154,000 ha) of field crops existed in
the Imperial Valley (Imperial Irrigation District (IID) 2009a). The
Imperial County has witnessed a decline in annual area used for
agricultural purposes from 1984 through 2008 of about 21,000 ac (8,000
ha) or 4 percent (CDC 2010), while the county saw an increase in area
used for urban areas in the same period of about 6,000 ac (2,400 ha) or
29 percent (CDC 2010). Urban expansion has accounted for only a
relatively small portion of the 4 percent decline in agricultural lands
over a period of 24 years. At this rate, conversion of agricultural
lands to urban lands in Imperial County has a modest impact.
Habitat in the Imperial Valley believed most important for mountain
plover includes alfalfa fields, especially those harvested then grazed
by sheep, and bermudagrass fields burned following harvest (Wunder and
Knopf 2002, pp. 75-76). Both alfalfa and bermudagrass acreages have
declined in recent years (2005-2009) (IID 2009a). However, in 2009,
these crops occupied 195,000 ac (79,000 ha) or approximately 51 percent
of total field crop acreage in the Imperial Valley (IID 2009a). Area
devoted to all hay (including alfalfa and bermudagrass), 233,000 ac
(90,000 ha), was the same in Imperial County in both 1997 and the 2007
(USDA 2010). Data available also suggest the number of sheep in the
Imperial Valley have declined recently as well but that numbers
fluctuate over time. It is not known whether these short-term declines
are indicative of future trends.
The continued success of agricultural habitats used by the mountain
plover in the Imperial Valley depends on a reliable water supply. The
Imperial Valley depends on Colorado River water to irrigate its crops,
but there has been increasing pressure for more water to be diverted to
urban areas. In 2003, the State of California and water agencies across
the State signed the Quantification Settlement Agreement (QSA) to
dictate distribution of water from the Colorado River. The settlement
allocated 370,000 acre-feet (ac-ft) (456 million cubic meters (cu-m))
of water to urban areas in Southern California and Tribal areas (IID
2010a, p. 2). Most of the 370,000 ac-ft (456 million cu-m) will come
from improvements in on-farm water efficiency and improved irrigation
technology (IID 2010a, p. 2; Delfino 2006, p. 161).
Under the QSA, Imperial County must also fallow agricultural land,
some of which will be transferred to the San Diego Water Authority, and
some of which will go to mitigation to restore the Salton Sea (IID
2010a, p. 1). The area of land fallowed depends on the intensity of
water use, not farm size (IID 2010b, p. 1). Fallowing will be conducted
on a sliding scale. The program began in 2003 with lands fallowed that
had been irrigated by under 10,000 ac-ft (1.2 million cu-m) of water,
and peaked in 2010 to lands fallowed that had been irrigated by over
80,000 ac-ft (9.9 million cu-m) of water. The program will slowly
decline before agricultural fallowing ends in 2017 (IID 2009b). The
area of land fallowed in 2009-2010 was about 10,500 ac (4,300 ha) or
about 2 percent of agricultural land in the valley. Overall, lands
fallowed will reduce the area of crop fields in the Imperial Valley but
we have no specific information as to extent to which those fields
fallowed provide wintering habitat to the mountain plover.
The future of the QSA is in question. On January 13, 2010, the
Superior Court of California found that funding provisions of the QSA
were unconstitutional, and officially invalidated the QSA on January
19, 2010 (QSA Coordinated Cases, Case No.: JC4353). IID asked for, and
received, a stay that temporarily allowed the terms of the QSA to
remain in effect (Case No.: JC4353). As of April 2011, a ruling was
anticipated before the end of the year (Imperial Valley Press 2011, p.
1). It is unclear what effect the cancellation of the QSA will have on
water use and fallowing, given the extreme contention and difficulty in
negotiating the 2003 settlement. If the stay does not remain in place,
the IID may halt fallowing, as it has been strongly opposed to
fallowing as a conservation measure (IID 2010c, p. 1). If the fallowing
program remains in place, it could continue as an immediate, but
relatively insignificant, threat to mountain plover habitat, as it
would only affect a small portion of agricultural fields, with no
definitive data indicating if (or how much) fallowing will occur on
those croplands that mountain plover frequent.
The yield from alfalfa crops is related to the amount of irrigation
the land receives (Hanson et al. 2007, p. 1). Alfalfa could thus be
more significantly impacted by water use restrictions. In California,
revenue for alfalfa is expected to decrease slightly by 2050,
decreasing 11 percent Statewide (Howitt et al. 2008, p. 11). These
statistics take water use into consideration (California Department of
Finance 2007, p. 5). In contrast, Bermudagrass is drought-tolerant, and
one study showed little decrease in crop yield under drought conditions
(Kneebone 1966, p. 96; George et al. 1992, pp. 23-24).
Yield and acreage of bermudagrass could be affected by restrictions
on burning in the Imperial Valley due to pollution concerns. To comply
with California's air pollution restrictions (California Code of
Regulations 2001, pp. 80100-80170), the Imperial County Air Pollution
Control District (ICAPCD) has set forth rules and regulations (ICAPCD
2010b, pp. 701.1-702.1) governing implementation of a smoke management
program (ICAPCD 2010a, pp. 1-37) for agricultural burning. These rules
and regulations allow for agricultural burning after the ICAPCD has
analyzed several factors: (1) Quantitative and qualitative analysis of
meteorological conditions; (2) current smoke complaints; (3) source/
receptor consideration; and (4) current air quality levels (ICAPCD
2010b, p. 8). The number of burn days permissible in the areas of
Imperial County has declined (California Air Resources Board 2010)
since 2003, but the amount of bermudagrass acreage burned in the same
period (2003 to 2009) shows little trend and averages about 18,000 ac
(7,000 ha) (Lancero, pers. comm.; Cavazos 2010, pers. comm.). Any
concern that current burning restrictions limit bermudagrass
cultivation appears unsupported by these data.
Future trends in alfalfa and Bermudagrass may largely determine the
extent and quality of mountain plover wintering habitat available in
the Imperial Valley. While no predictions of
[[Page 27788]]
future area devoted to these two crops is available, we do not have any
information that would lead us to conclude that their occurrence will
significantly decline. Therefore, we anticipate that in the future
substantial areas of alfalfa and Bermudagrass fields will remain
available to support wintering mountain plover in the Imperial Valley.
Currently, there is no habitat conservation plan (HCP) implemented
in the Imperial County. The Imperial Irrigation District is currently
working on an HCP, but they have not yet finalized the plan or been
issued a section 10(a)(1)(b) permit under the Act (Roberts 2010, pers.
comm.); however, in the current draft of the HCP, mountain plover is a
covered species.
Individually, urbanization, water restrictions, and trends in
agriculture do not appear to pose significant threats to the acreage or
quality of wintering habitat available or to the mountain plover's use
of the Imperial Valley. However, in the foreseeable future, their
combined effects, along with climate change, could appreciably reduce
habitat available to mountain plover and potentially affect the nature
or extent of wintering mountain plover use of the Imperial Valley.
Mountain plover winter over a large range and in diverse habitats.
In our February 16, 1999, proposed rule to list the species we cited
sources suggesting that most mountain plover, an estimated 7,000 of a
rangewide population of 8,000 to 10,000 birds, wintered in California
(64 FR 7587). However, we now believe that less than half of the
rangewide population, estimated at over 20,000 birds, winter in
California (see Population Size and Trends above). As of 2007, over 18
million ac (7 million ha) in California (about 18 percent of the State)
supported cropland, pastureland, or rangeland (USDA 2010). While only a
portion of this area provides habitat for the mountain plover in any
given winter, the total includes 1.7 million ac (0.7 million ha) of
alfalfa, Bemudagrass, and other hay crops that the mountain plover
utilizes, including 230,000 ac (90,000 ha) in Imperial County alone.
The total also includes 1.1 million ac (0.4 million ha) of pastureland,
often used by mountain plover. To exploit these and other wintering
habitats, mountain plover are able to move long distances and use
various sites as conditions become favorable within a given winter
(Knopf and Wunder 2006). Mountain plover appear annually at some
favored wintering sites, but site fidelity by individual birds appears
low. Birds may also alternate between wintering areas in California and
elsewhere in different years. Cumulatively, the potential changes in
land uses in California described above will likely result in a
reduction of mountain plover wintering habitat in the State. However,
given the available agricultural acreage cited above, it is not
apparent that even a reduction in California wintering habitat
substantially larger than that which we anticipate would significantly
affect California's ability to support mountain plover numbers
currently wintering in the State. We conclude that any likely reduction
of mountain plover wintering habitat in California will not threaten
the mountain plover plover's ability to maintain a wintering population
in California or threaten the species range wide in the foreseeable
future.
Wintering Outside of California
Elsewhere, in the Phoenix area, Maricopa County, and some other
wintering sites in southern Arizona, mountain plover have been
displaced by growth of human populations (Gardner 2010; Robertson 2010,
pers. comm.). Declines are likely to occur in the Tucson area, Pinal
County, and perhaps in Yuma County as well, due to increased human
populations and, more directly, due to an accompanying reduction in
agriculture. Wintering mountain plover populations in Cochise County,
where there is less urban development and where the amount of cropland
increased from 1997 to 2007 (USDA 2010), will likely remain more
stable. Solar energy development is occurring in areas of southern
Arizona, but the extent to which projects may overlap mountain plover
wintering habitat has not yet been determined.
Both increases in human population and expansion of agriculture are
occurring in areas of southern Arizona (Council for Agricultural
Science and Technology 2009, pp. 8-12). Rather than the total area
urbanized, the extent and nature of future agriculture that is present
in southern Arizona and available for mountain plover use will likely
dictate the future value of this area to wintering mountain plover.
However, water resources are limited, and urban uses may compete with
agriculture for available water. Southern Arizona is thought to winter
a relatively small portion of the rangewide mountain plover population.
We believe that any net future decreases in agricultural lands in
southern Arizona will be limited and that these potential future
decreases in agricultural lands in southern Arizona will not markedly
affect the ability of the area to support these wintering mountain
plover.
Other than potential impacts from wind energy development described
in Energy and Mineral Development above, we have no information
regarding threats to wintering mountain plover from habitat changes in
Texas.
Outside of the trends in wintering areas in Mexico described in
Threats to Prairie Dogs and Associated Loss of Habitat above, we have
little information regarding threats to the mountain plover from
wintering habitat changes in Mexico. Based on their wintering habitat
preferences in the United States, significant numbers of mountain
plover may winter in agricultural areas in Mexico. Possible areas of
concentration and the types of agriculture utilized remain
undocumented.
Summary of Factor A
The mountain plover occupies a wide geographic range across the
breeding, migration, and wintering seasons. The extensive and diverse
habitats it utilizes are subject to a number of changes that represent
potential threats.
Black-tailed prairie dogs create favorable breeding habitat for the
mountain plover in States including Colorado, Montana, and Wyoming.
Black-tailed prairie dog numbers have increased by a factor of six
since 1981 in States where they are present, and associated mountain
plover habitat has likewise increased. We do not anticipate loss of
black-tailed prairie dog numbers or the mountain plover habitat they
maintain in the foreseeable future.
Current conversion of prairie and grasslands to other land uses
within mountain plover breeding habitat appears negligible when viewed
from a rangewide perspective. Formerly expressed concerns regarding
human development in South Park, Colorado, where a high density of
mountain plover breeds, now seem unfounded.
Cattle grazing generally benefits mountain plover breeding habitat,
but some range management practices do not create favorable conditions
for mountain plover breeding. Specific range management to benefit
mountain plover could be employed, but overall we expect current cattle
grazing to continue relatively unchanged in the foreseeable future.
Suggestions that cropland use by breeding mountain plover may be
detrimental to populations have not been substantiated.
Energy and mineral development alters landscapes, and some
activities can adversely impact mountain plover habitat, at least
locally and temporally. The mountain plover often benefits from ground
disturbance and may tolerate or
[[Page 27789]]
benefit from certain development activities. Mountain plover collisions
with wind turbines are likely to occur infrequently. Overall, oil and
gas extraction, wind power projects, and mineral extraction have not
been shown to have significant adverse impacts to the mountain plover.
Wintering mountain plover are wide-ranging, and seek out a variety
of grassland, rangeland, crop field, and semi-desert landscapes, from
the Gulf Coast to the Pacific Ocean, to meet their needs. Habitat in
California and across the mountain plover's wintering range is dynamic,
based on yearly weather patterns, grazing levels, crops present, and
timing of planting or harvest. Currently available wintering habitat
can not be easily quantified, nor can its projected quantity and
quality in the foreseeable future be easily predicted. A future net
loss of wintering habitat in California appears likely, based on solar
development projects and other factors described above, but given the
expanse of wintering habitat currently present, it is not apparent that
this will have any affect on the number of wintering mountain plover
California will support.
Dinsmore et al. (2010) assessed factors affecting population growth
in the mountain plover in order to target conservation and management
efforts. They cited mountain plover adult survival as high in winter
and suggested conservation efforts should target increased chick
survival on breeding grounds. This is consistent with Knopf and Rupert
(1995, p. 750), who concluded that past declines in the mountain plover
were attributable to events taking place on the breeding grounds not
during winter. We believe that rather than changes in wintering
habitat, future changes on the mountain plover's breeding grounds that
influence reproductive success will dictate rangewide mountain plover
numbers and population trends. The quantity and quality of breeding
habitat, and the ability of the mountain plover to successfully
reproduce will depend largely on future human land uses, rangeland and
cropland management practices, the potential effects of energy
development, and the abundance and distribution of prairie dogs. We
have no credible evidence to show that future changes in the extent and
quality of mountain plover rangewide wintering habitat, of the
magnitude likely to occur, would significantly influence their total
population or population trend, or that they endanger the species now
or would be likely to endanger the species in the foreseeable future.
We conclude that the best information available indicates that the
mountain plover is not now, or in the foreseeable future, threatened by
the present or threatened destruction, modification, or curtailment of
its habitat or range to the extent that listing under the Act as an
endangered or threatened species is warranted at this time.
Factor B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Mountain plover were historically hunted for human consumption on
the Great Plains (Knopf and Wunder 2006). Under the Migratory Bird
Treaty Act (MBTA) (16 U.S.C. 703-712), mountain plover are not legally
hunted in the United States, Canada, or Mexico, although Andres and
Stone (2009, p. 27) note that some illegal shooting may occur in some
areas of Mexico. The extent or significance of any such activity is
unknown, but, because we have no information that such illegal hunting
activity is widespread, we believe it is unlikely to be a significant
threat to the mountain plover's continued existence.
Birders (bird watchers) may seek out mountain plover for viewing.
This activity is most likely to occur on a few publicized sites and
often takes place from, on, or near roadways. Mountain plover are
relatively tolerant of disturbance and often ignore humans in vehicles.
If approached on foot they quickly retreat (Knopf and Wunder 2006). We
believe that observation by birders does not represent a threat to the
mountain plover because it is limited in extent and most birders
attempt to minimize disturbance to birds as they pursue their
activities.
Most research conducted on mountain plover relies on passive
sampling (e.g., point counts) rather than active handling. Passive
sampling is not likely to substantially affect the mountain plover. The
studies that involve handling of adults, chicks, and eggs may impact
individuals, but these studies are small enough in scale that they are
not likely to affect populations as a whole. Knopf and Wunder (2006)
cautioned mountain plover eggs could become overheated if exposed to
direct sun on hot days. However, we do not have any information to
indicate that this has caused decreased nest success in areas where
research occurs.
Summary of Factor B
We do not have any evidence of risks to mountain plover from
overutilization for commercial, recreational, scientific, or
educational purposes, and we have no reason to believe that that this
factor will become a threat to the species in the foreseeable future.
We conclude that the best scientific and commercial information
available indicates that the mountain plover is not now, nor in the
foreseeable future, threatened by overutilization for commercial,
recreational, scientific, or educational purposes.
Factor C. Disease or Predation
Disease
We are not aware of any diseases or parasites that pose a threat to
the mountain plover at this time. West Nile virus, which has been
documented to cause deaths in many bird species, has not been found in
mountain plover (Andres and Stone 2009, p. 29). Since 2007, 4,888 dead
birds have been identified throughout California as deaths attributed
to the West Nile virus (California Department of Public Health (CDPH)
2010). Within this time span, West Nile virus has been reported from a
number of Central Valley counties, but to date no mountain plover
deaths have been attributed to the virus (CDPH 2010). Over the same
time period, there have been no bird deaths associated with West Nile
virus in Imperial County.
Dreitz et al. (2010) investigated causes of mortality in mountain
plover chicks and reported preliminary analysis of blood samples from
chicks in Colorado and Montana. Blood parasitism was low in Colorado,
and none was detected in Montana.
The Intergovernmental Panel on Climate Change (IPCC) (2007, p. 51)
suggests that the distribution of some disease vectors may change as a
result of climate change. However, we have no information to suggest
any specific disease may become problematic to the mountain plover as a
result of climate change.
Predation
The list of predators on mountain plover, their nests, and young is
extensive, and includes the American badger (Taxidea taxus), skunks
(Spilogale spp. and Mephitis spp.), ground squirrels, swift fox (Vulpes
velox), coyote (Canis latrans), bullsnake (Pituophis catenifer),
Swainson's hawk (Buteo swainsoni), prairie falcon (Falco mexicanus),
common raven (Corvus corax), great-horned owl (Bubo virginianus),
burrowing owl (Athene cunicularia), and loggerhead shrike (Lanius
ludovicianus) (Smith and Keinath 2004, p. 20; Andres and Stone 2009, p.
28).
Survival rates of adult mountain plover are thought to be quite
high on
[[Page 27790]]
both breeding and wintering grounds, and it is unlikely that predation
of adult mountain plover constitutes a significant concern to mountain
plover populations overall (Smith and Keinath 2006, p. 19). Emphasis
has been largely placed on predation of nests and chicks (Kopf and
Wunder 2006; Andres and Stone 2009, p. 28; Dreitz et al. 2010, entire).
Survival of nests to hatching is similar to or greater than that found
in other ground-nesting prairie shorebirds in the Great Plains, and
nest success does not appear to be a limiting factor to population
growth of the species (Dinsmore et al. 2010). Survival of chicks from
hatching to fledging has been highlighted as a potentially important
life stage that could be targeted for management to support the
conservation and expansion of mountain plover populations, for example,
from habitat improvements that may reduce predation rate (Dinsmore et
al. 2010).
Knopf (2008, p. 50) cited the swift fox as the major predator on
eggs and the primary predator on chicks on the PNG in Colorado, and
suggested that reduced predator control and subsequent increase in
predators was a contributing factor in the dramatic decline in mountain
plover the area experienced. Thirteen-lined ground squirrels
(Spermophilus tridecemlineatus) have been the greatest source of nest
predation in South Park, Colorado (Wunder 2010b, pers. comm.). Chick
monitoring in Colorado in 2010 confirmed 38 mortalities, including 13
from avian predation (most on less than 16-day old chicks by burrowing
owls) and 8 by mammalian predators including swift fox and American
badger (Dreitz et al. 2010, pp. 3-4). Predation by unknown species was
suspected in some other deaths (Dreitz et al. 2010, pp. 3-4). Similar
research in Montana in 2010 implicated black-billed magpies (Pica
hudsonia) as a possible cause of disappearances of chicks whose fate
was not confirmed.
Knopf and Wunder (2006) suggested mountain plover nest visits by
researchers could lead to predation by ravens (Corvus spp.). Similarly,
nest marking to avoid nest destruction during agricultural operations
may alert predators to nest locations.
We do not believe that natural levels of predation present a threat
to the mountain plover, although the risk could be increased through
human development and habitat fragmentation. This may result where
predators concentrate their foraging activities and movements along
habitat edges. However, Mettenbrink et al. (2006, p. 195) looked at
mountain plover nesting in a prairie landscape fragmented by crop
fields and found little relationship between nest predation and
distance to habitat edges. The authors concluded that predators of
mountain plover in the shortgrass prairie apparently do not hunt
selectively along anthropogenic (human-created) edges. Roads may serve
as travel routes for predators (Pitman et al. 2005, p. 1267), and
natural gas development has been shown to increase the occupancy of the
common raven, a potential predator of mountain plover nests and chicks,
in sage brush habitat (Bui et al. 2010, pp. 73-74). Increases in roads
and structures associated with energy development could result in
increased predation on mountain plover nests or chicks. However, Carr
(in review) found no relationship between mountain plover nest success
and road or well density.
While predation accounts for a major portion of chick mortality, we
have no information that would lead us to conclude that predation on
mountain plover chicks differs from levels experienced by other upland
nesting shorebirds or that, across the range of the mountain plover, it
is a current or future threat to the survival of the species.
Summary of Factor C
We do not find evidence that disease is currently impacting the
mountain plover, nor do we have information to indicate that disease
outbreaks will increase in the future. While the level of predation on
mountain plover nests and chicks is high, it is not inconsistent with
that found in other ground-nesting bird species. Fragmentation of
habitats, including that associated with energy development, could
increase predation, but evidence to date does not suggest any increase
is occurring. We do not have information at this time to indicate that
predation is impacting the mountain plover at a level that threatens
the species. We conclude that the best scientific and commercial
information available indicates that the mountain plover is not now, or
in the foreseeable future, threatened by disease or predation to the
extent that listing under the Act as an endangered or threatened
species is warranted at this time.
Factor D. The Inadequacy of Existing Regulatory Mechanisms
Under this factor, we examine whether existing regulatory
mechanisms are inadequate to address the threats to the mountain plover
discussed in Factors A, B, C and E. The Service considers regulatory
mechanisms to mean all mechanisms that are related to a comprehensive
regime designed to maintain a conserved wildlife population. In
addition to the five factors that section 4(a)(1) of the Act directs
the Service to consider, section 4(b)(1)(A) of the Act requires the
Service to take into account, ``those efforts, if any, being made by
any State or foreign nation, or any political subdivision of a State or
foreign nation, to protect such species. * * *'' We consider these
efforts when developing our threat analyses under all five factors and
in particular under Factor D. Therefore, under Factor D we consider not
only laws and regulations, but other mechanisms that are part of a
regulatory process such as management plans and agreements,
conservation practices, and so forth.
In analyzing whether the existing regulatory mechanisms are
inadequate, the Service reviews relevant Federal, State, and Tribal
laws, plans, regulations, Memoranda of Understandings (MOUs),
Cooperative Agreements, and other such mechanisms that influence
conservation. We give strongest weight to statutes and their
implementing regulations, and management direction that stems from
those laws and regulations. An example would be the terms and
conditions attached to a grazing permit that describe how a permittee
will manage livestock on a BLM allotment. They are non-discretionary
and enforceable, and are considered a regulatory mechanism under this
analysis. Other examples include State governmental actions enforced
under a State statute or constitution, or Federal action under statute.
Some other agreements (MOUs and others) are more voluntary in nature;
in those cases we analyze the specific facts for that mechanism to
determine the extent to which it can be relied on in the future. We
consider all pertinent information, including the efforts and
conservation practices of State governments, whether or not these are
enforceable by law. Regulatory mechanisms, if they exist, may preclude
the need for listing if such mechanisms are judged to adequately
address the threat to the species such that listing is not warranted.
Conversely, threats on the landscape are not ameliorated when not
addressed by existing applicable regulatory mechanisms, or when the
existing mechanisms are not adequate (or not adequately implemented or
enforced). We cannot predict when or how State and Federal laws,
regulations, and policies will change; however, most Federal land use
plans are valid for at least 20 years. In this section, we review
actions undertaken by State and Federal
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entities designed to reduce or remove threats to mountain plover and
its habitat.
Federal Laws and Regulations
The mountain plover is covered under the provisions of the
Migratory Bird Treaty Act (MBTA), which provides regulatory protection
for mountain plover by prohibiting actions causing direct mortality and
destruction of nests. In addition, the mountain plover is listed as a
Bird of Conservation Concern by the Service in all 12 Bird Conservation
Regions encompassing the species' breeding and wintering ranges. Birds
of Conservation Concern represent the highest conservation priorities
under the MBTA for the Service's Migratory Bird Program (Service 2008,
p. iii). The goals of the Service's Migratory Bird Program include the
protection, restoration, and management of migratory bird populations
to ensure long-term ecological sustainability (Service 2011). The
Service's goal is to prevent or remove the need for additional bird
listings under the Act by implementing proactive management and
conservation actions. The list is to be used to develop research,
monitoring, and conservation actions to stimulate coordinated and
collaborative proactive conservation actions among Federal, State,
Tribal, and private partners (Service 2008, p. iii). However, the
designation as a Bird of Conservation Concern does not in and of itself
provide any extra protections for the mountain plover or its habitat.
The BLM and the USFS are the primary Federal agencies that manage
lands that provide breeding or wintering habitat for the mountain
plover. The BLM's lands and USFS-managed National Grasslands provide
important breeding habitat in Montana, Wyoming, Colorado, and New
Mexico. The BLM's lands in California and southern Arizona may provide
habitat for wintering mountain plover.
The Federal Land Policy and Management Act of 1976 (FLPMA) (43
U.S.C. 1701 et seq.) is the primary Federal law governing most land
uses on BLM-administered lands. Section 102(a)(8) of FLPMA (43 U.S.C.
1701(a)(8)) specifically recognizes wildlife and fish resources as
being among the uses for which these lands are to be managed.
Regulations pursuant to FLPMA and the Mineral Leasing Act (30 U.S.C.
181 et seq.) that address wildlife habitat protection on BLM-
administered land include 43 CFR 3162.3-1 (Drilling applications and
plans) and 43 CFR 3162.5-1 (Environmental obligations); subpart 4120
(Grazing Management) of Title 43 of the Code of Federal Regulations
(CFR); and subpart 4180 (Fundamentals of Rangeland Health and Standards
and Guidelines for Grazing Administration) of Title 43 of the CFR.
Mountain plover have been designated as a BLM Sensitive Species in
Colorado (BLM 2000a), California (BLM 2006), and Wyoming (BLM 2010a).
The management guidance afforded sensitive species under BLM Manual
6840--Special Status Species Management (BLM 2008, entire) states that
``Bureau sensitive species will be managed consistent with species and
habitat management objectives in land use and implementation plans to
promote their conservation and to minimize the likelihood and need for
listing under the [Act]'' (BLM 2008, p. 05V). The BLM Manual 6840
further requires that Resource Management Plans (RMPs) should address
sensitive species, and that implementation ``should consider all site-
specific methods and procedures needed to bring species and their
habitats to the condition under which management under the Bureau
sensitive species policies would no longer be necessary'' (BLM 2008, p.
2A1). See our discussion above under Factor A, Energy and Mineral
Development, for more on measures the BLM has taken in Wyoming to
conserve the mountain plover as a sensitive species.
The BLM in Montana has designated a Mountain Plover Area of
Critical Environmental Concern (ACEC), which contains 24,730 ac (9,892
ha) of habitat suitable for breeding mountain plover (BLM 2000b, p.1).
Management prescriptions apply within the ACEC to protect breeding
mountain plover during its nesting period. All construction activity
and surface disturbance are prohibited from April 1 to July 31, road
construction is minimized within the ACEC, and seasonal restrictions
also apply to off-highway travel (BLM 2000b, pp. 8-9). While the ACEC
is a focus of BLM's efforts to conserve the mountain plover, the area
covers only a small fraction of all mountain plover habitat in Montana.
As a designated sensitive species under BLM Manual 6840, mountain
plover conservation must be addressed in the development and
implementation of RMPs on BLM lands. RMPs are the basis for all actions
and authorizations involving BLM-administered lands and resources. They
establish allowable resource uses, resource condition goals and
objectives to be attained, program constraints and general management
practices needed to attain the goals and objectives, general
implementation sequences, and intervals and standards for monitoring
and evaluating the plan to determine effectiveness and the need for
amendment or revision (43 CFR 1601.0-5(n)). The RMPs provide a
framework and programmatic guidance for activity plans, which are site-
specific plans written to implement decisions made in an RMP. Examples
include Allotment Management Plans that address livestock grazing, oil
and gas field development, travel management (motorized and mechanized
road and trail use), and wildlife habitat management. Activity plan
decisions normally require additional planning and National
Environmental Policy Act (NEPA; 42 U.S.C. 4321 et seq.) analysis. If an
RMP contains specific direction regarding mountain plover habitat,
conservation, or management, it represents an enforceable regulatory
mechanism to ensure that the species and its habitats are considered
during permitting and other decision-making on BLM lands.
The BLM has regulatory authority for oil and gas leasing on Federal
lands and on private lands with a severed Federal mineral estate, as
provided at subpart 3100 (Onshore Oil and Gas Leasing; General) of
Title 43 of the CFR, and they are authorized to require stipulations as
a condition of issuing a lease. They can condition ``Application for
Permit to Drill'' authorizations, conducted under a lease that does not
contain specific mountain plover conservation stipulations, but
utilization of conditions is discretionary, and we are uncertain as to
how this authority is applied.
Management of National Forest System lands is guided principally by
the National Forest Management Act (NFMA) (16 U.S.C. 1600-1614, August
17, 1974, as amended). The NFMA specifies that all National Forests
must have a Land and Resource Management Plan (LRMP) (16 U.S.C. 1604)
to guide and set standards for all natural resource management
activities on each National Forest or National Grassland. The NFMA
requires USFS to incorporate standards and guidelines into LRMPs (16
U.S.C. 1604(c)). The USFS conducts NEPA analyses on its LRMPs, which
include provisions to manage plant and animal communities for
diversity, based on the suitability and capability of the specific land
area in order to meet overall multiple-use objectives. The USFS
planning process is similar to that of the BLM. The mountain plover is
a USFS sensitive species in Region 2, which includes all of Colorado
and portions of Wyoming and Nebraska.
The USFS policy provides direction to analyze potential impacts of
proposed
[[Page 27792]]
management activities to sensitive species in a biological evaluation.
The LRMPs for grassland units within USFS Region 2 (PNG, Nebraska
National Forest, and Thunder Basin National Grassland in Wyoming)
contain management direction for the mountain plover (USFS 2001). Some
examples of the LRMP standards (required measures) for the three areas
include: (1) Prohibiting development of new facilities within 0.25 mi
(0.40 km) of known mountain plover nests or nesting areas; (2) limiting
vehicle speeds in occupied mountain plover habitat to 25 miles per hour
(mph) (40 kilometers per hour (kph)) on resource roads and 35 mph (56
kph) on local roads; (3) designing vegetation management projects in
suitable mountain plover habitat to maintain or improve mountain plover
habitat; and (4) maintaining occupied nesting and brooding habitat on
black-tailed prairie dog colonies by limiting new oil and gas
development to one well per 80 ac (32 ha) within occupied habitat.
Cumulatively, structure and facility development will not occur on more
than 2 percent of the occupied mountain plover nesting habitat in each
prairie dog colony on the Thunder Basin National Grasslands (USFS
2001). As described above in the discussion under Factor A, the PNG has
been conducting prescribed burning for many years to improve breeding
habitat for mountain plover (Knopf 2008, pp. 25-26). Numerous research
projects on mountain plover have also been conducted on the PNG and the
adjacent USDA Research Area (Augustine 2010a, pers. comm.; Augustine
2010b, pers. comm.).
In Colorado and Wyoming, a multi-agency team, consisting of
biologists from the Service, BLM, USFS, and National Park Service,
developed a non-regulatory screening tool to allow for proactive and
consistent management and conservation of the mountain plover on public
lands and to provide a tool for streamlining agency review and
implementation of activities (BLM 2004). The screening tool allows
agency personnel to evaluate the impacts of projects (such as energy
development, rangeland management, and recreation) that would occur
within or adjacent to mountain plover habitat to determine whether the
project would result in an impact to the species at the local or
rangewide scale. Use of the screening tool would not stop any projects
from occurring, but rather would alert agency personnel to possible
project impacts so that the project could be modified if possible.
While the screening tool provides a good non-regulatory mechanism for
Federal biologists in Colorado and Wyoming to evaluate the effects of
their proposed actions, it does not require that projects ultimately
have no effect on mountain plover. However, this screening tool
provides for advanced notice of actions and facilitates coordination
between the multi-state agency team.
The Federal laws, regulations, and actions cited above are designed
to reduce or remove threats to the mountain plover and its habitat.
There is no information available to indicate that the species is
threatened by the inadequacy of existing Federal laws and regulations.
State and International Laws and Regulations
The Nebraska Game and Parks Commission lists the mountain plover as
``threatened.'' But, this regulatory mechanism likely protects
relatively few individuals (see Conservation Status and Local
Populations above). While some States, such as Colorado, have specific
management plans that address mountain plover conservation, and all
States within the range of the species include it within their State
Wildlife Conservation Strategies (see Conservation Status and Local
Populations above), there is no rangewide or intrastate coordinated
management effort and no requirement to implement specific management
actions. However, there is no information available to indicate that
the species is threatened by the inadequacy of existing State
regulatory mechanisms.
Canada
The mountain plover has been listed as endangered in Canada since
1987. Knapton et al. (2006, p. i) noted that listing was in part due to
a perceived decline from 1980 to 1986. The Species At Risk Act (SARA),
passed December 12, 2002, is a commitment by the Canadian government to
prevent the extinction of wildlife and provide the necessary actions
for the recovery of species deemed endangered. These at-risk wildlife
species are provided with legal protection under SARA, and their
biological diversity is thereby conserved (Environment Canada 2010). As
noted in the Background section above, the mountain plover population
in Canada is very small, and efforts there to improve habitat will not
likely have a significant impact on this species' conservation
rangewide. There is no information available to indicate that the
species is threatened by the inadequacy of existing regulatory
mechanisms in Canada.
Mexico
In 2001, Mexico established a list of species classified as
endangered, threatened, under special protection, or probably extinct
in the wild (Commission for Environmental Cooperation (CEC) 2011). The
mountain plover was listed as threatened (Andres and Stone 2009, p.
14). Under the General Wildlife Law, the use of at-risk species may be
authorized only for the collection and capture for restoration,
repopulation, and reintroduction activities (CEC 2011). However,
regulatory powers and wildlife management prerogatives reside largely
with the Federal government with States taking a more minor role.
Shifting Federal agency responsibility and lack of agency funding
results in inadequate protection and management of wildlife resources
(Valdez et al. 2006, p. 277). Although regulatory mechanisms in Mexico
appear to be minimal or are not adequately enforced, Mexico constitutes
a small portion of the overall species' breeding range. Mountain plover
appear to winter in significant numbers in Mexico, but at that time of
year, they are highly mobile and less vulnerable to human activity than
when nesting, and they therefore may require few regulatory
protections. There is no information available to indicate that the
species is threatened by the inadequacy of existing regulatory
mechanisms in Mexico.
Summary
While mountain plover conservation has been addressed in some
State, Federal, and international plans, laws, regulations, and
policies, none of these have applicability throughout the range of the
mountain plover sufficient to provide effective population-level
conservation. However, we have found in the analysis of the other four
factors (A, B, C, and E) that there are no activities that currently
rise to the level of a significant threat to the mountain plover.
Therefore, we conclude that the best scientific and commercial
information available indicates that the mountain plover is not now,
and is not expected to become within the foreseeable future, threatened
by the inadequacy of existing regulatory mechanisms to the extent that
listing under the Act as an endangered or threatened species is
warranted at this time.
[[Page 27793]]
Factor E. Other Natural or Manmade Factors Affecting the Species'
Continued Existence
Genetic Diversity
The loss of local populations may impact a species because local
populations may possess unique genetic characteristics that are
important to the species' genetic diversity and its ability to adapt to
future environmental changes. However, for mountain plover, genetic
studies using nuclear microsatellites have concluded that mountain
plover across sampled breeding locations in Colorado and Montana
comprise a single, relatively homogenous gene pool (Oyler-McCance 2005,
p. 359; Oyler-McCance et al. 2008, pp. 496-497). These results suggest
that there is sufficient gene flow among breeding areas to offset
reported adult fidelity to breeding areas and genetic effects of small
populations (genetic drift, loss of genetic diversity) (Oyler-McCance
et al. 2005, p. 360; Oyler-McCance et al. 2008, pp. 496-497). While
this seems unusual for a species with relatively high reported site
fidelity, it suggests pair formation in mixed winter flocks from
different breeding areas. Widespread mixing of mountain plover
populations in winter has been documented (Wunder 2007, p. 118). From a
genetic perspective, this information suggests that no single breeding
population requires special conservation or protection (Oyler-McCance
et al. 2005, p. 360). However, not all populations have received
genetic analysis, including potentially non-migratory breeding
populations in Mexico. We conclude that there is no known restriction
of gene flow within the species, and that the loss of any given local
population will not substantially impact the genetic diversity of the
mountain plover or the species' ability to adapt to future stressors.
Longevity, Site Fidelity, and Sex Ratio
In our December 5, 2002, proposed listing rule (67 FR 72396), we
stated, ``* * * that because the average lifespan of a mountain plover
is less than 2 years, and breeding does not occur until 1 year of age,
an individual mountain plover will likely have only one breeding season
to contribute to population recruitment.'' Previous study results
underestimated adult survival and, more importantly, our proposed rule
erroneously concluded that average lifespan reflected typical adult
survival. In the best available estimate of adult mountain plover
survival, the annual survival rate of adult mountain plover of both
sexes in Phillips County, Montana, ranged from 0.74 to 0.96 yearly
(Dinsmore 2008, p. 50). Based on this study, a mountain plover
returning to its breeding ground would likely return multiple
additional years. Dinsmore et al. (2010) characterized the mountain
plover as typical of relatively long-lived bird species, documented to
live over 10 years, where repeated reproductive attempts throughout
life are less important to population growth than adult survival. On
the basis of our review of the best available information, we now
believe that a short average lifespan and resulting limited
reproductive opportunities, as suggested in our 2002 proposal, do not
constitute a threat to the mountain plover.
In our February 16, 1999 (64 FR 7587), and December 5, 2002 (67 FR
72396), proposals to list the mountain plover as a threatened species,
we considered the plover to have high fidelity to breeding sites. In
patchy habitat, when nesting habitat is destroyed or unavailable, it
may be difficult for the mountain plover to find a new place to breed,
thus resulting in the decline of populations. Dispersal ability may be
important to the use of available habitat and conservation of the
mountain plover given the patchiness of desirable breeding habitat.
Altered or fragmented landscapes may force mountain plover to disperse
greater distances. For example, in Montana, where the mountain plover
is highly dependent on black-tailed prairie dog colonies for breeding
habitat, sylvatic plague outbreaks often make previously used breeding
habitat undesirable. As discussed above, Skrade and Dinsmore (2010, pp.
671-672) demonstrated the mountain plover's ability to disperse at
least locally to exploit favorable breeding habitats nearby, and in at
least one instance, an adult mountain plover returned to breed at a
site about 25 mi (40 km) from a site where it was banded during the
previous season. We conclude that while the mountain plover generally
exhibits fidelity to breeding sites, it is capable, at least locally,
of seeking out and exploiting new habitat through both juvenile
dispersal and through adult birds returning to different breeding sites
in subsequent years. On a local scale (several mi/km), loss or
fragmentation of breeding habitat is unlikely to have an inordinate
effect on mountain plover survival and reproduction (i.e., effects are
likely to be proportional to, but not in excess of the amount of
habitat loss).
Previously, concern arose as to whether a preponderance of male
mountain plover among those birds handled by researchers in California
suggested a skewed sex ratio (more males than females) range wide and
whether this might adversely affect reproductive potential. Knopf
(2003, pers. comm.) speculated that a slightly unbalanced sex ratio in
California might result from slightly higher overall mortality in
females or from differential wintering, with females wintering further
south, in Mexico. Rangewide sex ratios for mountain plover are still
unknown (Knopf and Wunder 2006) and we have no evidence that relative
number of males and females in mountain plover populations represents a
threat to the species.
Exposure to Pesticides
Potential exposure of mountain plover to pesticides and
agrochemicals on wintering areas in California, and resulting impacts
to mountain plover health and reproduction, have been cited as a
potential threat (Knopf and Wunder 2006). Exposure of mountain plover
to direct pesticide application is likely minimized because most
pesticide application occurs on growing crops, and less frequently on
harvested and fallow fields, or grazed pastures that mountain plover
frequent.
The organochlorine agricultural pesticide DDT, and its byproduct
DDE, can cause thinning of eggshells and decreased reproductive success
in birds (Longcore et al. 1971, pp. 486, 489). DDT has not been in use
in California since the 1970s, and in many cases, DDE levels that
remain in the environment will decrease slowly over several decades
(Thomas et al. 2008, pp. 55, 65). Organochloride levels in mountain
plover collected from three California counties (Imperial, San Luis
Obispo, and Tulare) in 1991-1992 ranged from 1.0 to 10.0 parts per
million (ppm) (dry weight); although these levels are considered high
for an upland bird, no subsequent issues with bird behavior or eggshell
thickness in mountain plover were noted (Knopf and Wunder 2006). Levels
of DDE of 43 ppm (wet weight) were found in eggs collected from
abandoned mountain plover nests in Park County, Colorado, in 2001
(Knopf and Wunder 2006). No effects on eggs, chicks, or adult mountain
plover were established.
Historically, soils in the Imperial Valley are known to be high in
DDE (California Department of Food and Agriculture (CDFA) 1985, p. 27).
Studies have shown unchanging levels of the chemical in the past
decades; this suggests a persistent, local source of the chemical
(Gervais and Catlin 2004, pp. 509-510). The Imperial Valley is the
suspected source for high DDE concentrations and decreased reproductive
success in white-faced
[[Page 27794]]
ibises (Plegadis chihi) (Yates et al. 2010, p. 159). Levels of DDE in
resident burrowing owls are suspected to act as a stressor, but
reproductive effects have not been documented (Gervais and Anthony
2003, p. 1259).
Service biologists recently collected and analyzed mountain plover
eggs, soils, and soil invertebrates from breeding areas in Colorado,
Wyoming, and Montana, and soils and soil invertebrates from wintering
areas in the Imperial Valley (Zeeman 2011, pers. comm.). Chemical
analyses of eggs showed measurable, and in some cases high, levels of
persistent organic pollutants, most notably DDE. Much lower
concentrations of polychlorinated biphenyls (PPBs), hexachlorobenzene,
tetrachlorobenzenes, alpha chlordane, oxychlordane (chlordane
metabolite), heptachlor epoxide, and dieldrin were found. Contaminants
detected in mountain plover eggs were also detected in soil and
invertebrate samples from fields in Imperial Valley, but no measurable
levels were found in soil and invertebrates at the breeding grounds.
The upper concentrations of DDE detected, 50 ppm (wet weight) in
two eggs, was within the range of values (which can range from as low
as 3 ppm in sensitive species to 30 ppm in less sensitive species)
associated with eggshell thinning and reproductive impairments in wild
birds (Blus 1996). Conspicuous signs of impacts associated with DDE
exposure, such as eggshell cracking and embryo malformation, were not
detected in mountain plover (Zeeman 2011, pers. comm.). Based on
concentrations found in eggs, DDE from wintering areas, including the
Imperial Valley, could potentially affect mountain plover (Zeeman 2011,
pers. comm.). The potential for the other contaminants detected in
eggs, both individually or in combination, to affect the mountain
plover is being evaluated by the Service (Zeeman 2011, pers. comm.).
The results cited above suggest that exposure varies by individual and
that few mountain plover have DDE levels that raise a concern. In
addition, no effects of DDE to adult mountain plover, their eggs, or
chicks have been established. At this time, we believe that if an
effect occurs, it would probably be localized, and would affect
individual birds or eggs and not have an effect at a population or
species level.
Certain organophosphate insecticides are still used to control
insect pests on crops in California's Central Valley within the range
of the mountain plover. Iko et al. (2003, p. 119) measured
cholinesterase levels in mountain plover, a measure of exposure to
organophosphorus and carbamate insecticides, and found that they varied
widely between mountain plover collected in California from the Central
Valley where pesticide use is widespread and from the Carrizo Plain
where there is minimal pesticide use, but no differences were observed
in mountain plover body condition.
The Central Valley is one of the State's primary growing regions
for alfalfa. Sixty percent of the State's hay crop is grown here, with
over 600,000 ac (240,000 ha) planted to alfalfa within the Central
Valley (Godfrey 2002, p. 4). Insecticides used on alfalfa pests include
chlorpyrifos, malathion, and pyrethroids. Insecticide applications in
alfalfa usually occur once insects reach damaging levels, typically in
March or later in the growing season (Godfrey 2002, pp. 4-10),
suggesting that exposure of wintering mountain plover to treatments
would be limited, if any. Because early spring insecticide treatments
in alfalfa have been found to largely eliminate nontarget insect
species complexes (Godfrey 2002, pp. 4-6), an unknown but potential
residual effect to mountain plover prey availability may exist in
specific areas the following winter. If present, such an effect could
locally reduce desirability of certain alfalfa fields to wintering
mountain plover, but would not have a rangewide impact to the species.
Malathion, a broad-spectrum organophosphate insecticide, has been
used to control the beet leaf-hopper (Circulifer tenellus) in rangeland
habitat, fallow fields, oil fields, and cultivated areas on both public
and private lands in the San Joaquin Valley (BLM 2002, pp. 1-2; CDFA
2007, p. 8; CDFA 2008, pp. 1-4). The beet leaf-hopper is a vector for
curly top virus, which negatively affects crops. In the western and
southern portions of the San Joaquin Valley, aerial spraying may occur
fall through spring, and may include treatment of approximately 200,000
ac (80,000 ha) in years with high beet leaf-hopper populations.
Treatment usually results in a target population decline of over 90
percent (CDFA 2008, pp. 1-4). Potential impacts to the mountain plover
from the control treatments could result from both direct exposure and
indirectly from the reduction of insect prey (CDFA 2007, p. 79).
Although beet leaf-hopper control is potentially immense in scale,
in the 10 years up to 2002, an average of only about 4,400 ac (1,800
ha) per year were treated in the bird's wintering range within the San
Joaquin Valley, primarily in sloped terrain that is not thought to be
desired by the mountain plover (CDFA 2007, p. 79). The limited area and
quality of mountain plover habitat treated, coupled with the species'
large wintering range in California, led the CDFA to determine that the
curly top treatment program would not be likely to significantly impact
the mountain plover (CDFA 2007, p. 80). On public lands managed by the
BLM, prescribed usage avoids malathion spraying on wintering mountain
plover areas when the plover is present (BLM 2002, p. 1).
Chemical exposure in Mexico where regulations and enforcement may
be less stringent could be of concern (Andres and Stone 2009, p. 30).
DDE levels in mountain plover eggs reported by Zeeman (2011, pers.
comm.) may have resulted from exposure in Mexico, where DDT is still
used. While we believe that crop fields in Mexico have potential to
support large numbers of wintering mountain plover, significant
mountain plover use of crop fields in Mexico has not been reported
(Macias-Duarte and Punjabi 2010, pp. 3, 7), nor have specific issues
regarding pesticide use and impact to mountain plover been identified.
While changing agricultural practices regarding pesticide application
or evolution of new chemicals for use in the United States or Mexico
could prove a future threat, we have no basis for predicting the
potential of such an occurrence.
We have no evidence that pesticides are significantly impacting
mountain plover populations either locally or rangewide. However, given
the information summarized above, additional evaluation of any possible
effects to mountain plover from former and ongoing pesticide use within
the mountain plover's range appears prudent.
Selenium Toxicity
Within the western San Joaquin Valley, selenium is present in the
soil and has the potential to occur in ponded irrigation water in
fields and drainages. Irrigation with drainwater used to flood wetlands
has resulted in biological accumulation of selenium sufficient to harm
reproduction of shorebirds and other wildlife (Ohlendorf et al. 1987,
pp. 169-171, 174-181). Potential effects of selenium poisoning on birds
can include gross embryo deformities, winter stress syndrome, depressed
resistance to disease due to depressed immune system function, reduced
reproductive success, reduced juvenile growth and survival rates, mass
wasting, loss of feathers (alopecia), embryo death, altered enzyme
function, and mortality (Ohlendorf 1996, pp. 131-139; O'Toole and
Raisbeck 1998, pp. 361-380). Species exposed to multiple
[[Page 27795]]
stressors can become more vulnerable to exposure to selenium.
Because the mountain plover is an upland bird feeding primarily on
terrestrial insects, its habits may limit its exposure to selenium.
Still, selenium bioaccumulation in the food chain could create a
contaminant hazard for mountain plover feeding on insects in alkaline
flats, grazed pastures, and plowed fields in this area. Specific
exposure of the mountain plover to selenium, or any adverse effects of
such exposure have not been documented.
In summary, it has been documented that mountain plover have been
exposed to various levels of potentially harmful pesticides and
chemical toxins in various portions of its range. However, we have no
information to indicate that the mountain plover is responding
negatively to this exposure or that it is likely to respond negatively
in the future. Exposure levels that elicit negative responses in other
bird species do not appear to elicit a similar negative response in
mountain plover. Therefore, we do not believe that mountain plover are
threatened by exposure to pesticides and chemical toxins.
Grasshopper and Cricket Control
Efforts to control grasshoppers and Mormon crickets, especially
Federal control programs on BLM lands, have been cited as potentially
detrimental to breeding mountain plover. Grasshoppers occur throughout
the breeding range of the mountain plover and can reach population
levels considered to be a threat to agriculture. The USDA's Animal and
Plant Health Inspection Service (APHIS) conducts rangeland grasshopper
and Mormon cricket control, including areas occupied by breeding
mountain plover. Logically, a significant reduction in these mountain
plover foods could affect mountain plover fecundity and survival.
However, efforts to control grasshoppers and Mormon crickets on Federal
lands are generally limited to suppressing populations in years and
areas where infestations occur, and do not have the goal of
eradication, but rather the goal of reducing densities to levels that
limit economic impacts (BLM 2010b). Numbers of these insects present
after treatment may remain greater than those present in a normal year.
The BLM currently is pursuing a strategy of ``reduced area and agent
treatments,'' with the majority of treatments through aerial spraying
of a pesticide (diflubenzuron, a chiton inhibitor) with limited impacts
to non-target species (BLM 2010b). Broad spectrum insecticides
(carbaryl and in limited cases malathion) are used more sparingly, and
as a secondary treatment.
Control on private lands can be undertaken by State or local
government agencies, or private landowners without participation or
oversight by APHIS. Treatment on private lands likely varies depending
on resources available and the economic implications of infestations.
Where treatment occurs, it likely has the similar goal of reducing
insect densities to acceptable levels. Grasshopper and cricket control
can have an impact on mountain plover prey and could, in some years and
at some locations, adversely affect mountain plover breeding. However,
since the scope and impact of these control efforts appear minimal
relative to the mountain plover breeding range, we conclude that
grasshopper and Morman cricket control does not represent a significant
threat to rangewide mountain plover populations.
Weather
Annual weather variation influences mountain plover habitat and
breeding success. Inclement weather may hinder egg laying (Knopf and
Wunder 2006). Cold, rain, and hail can result in loss of nests and
decreased chick survival. Dreitz et al. (2010, pp. 3-4) identified
weather as a significant cause of chick mortality. Mammalian predators
of mountain plover eggs and chicks are scent-driven, and wet conditions
enhance predation (Knopf and Wunder 2006; Wunder 2007, p. 121).
Wunder (2007, pp. 119-121) presented evidence that recruitment may
be linked to regional patterns of weather, with highest recruitment
coming from breeding areas with low precipitation and a subsequent 1-
to 2-year lag observed in increased populations of adults (Wunder 2007,
pp. 119-121). Productivity may be influenced by drought cycles, with
dry years reducing predation from mammals and suppressing vegetative
growth, thus providing increased accessibility to insects. Annual
survival of mountain plover in Montana proved higher during periods of
drought, although prolonged drought eventually decreases abundance of
insect foods (Dinsmore 2008, p. 52). Weather variation affects mountain
plover productivity across its breeding range, but we have no evidence
that normal weather fluctuations represent a threat to the mountain
plover.
Climate Change
There is no information available on the direct relationship
between the environmental changes associated with climate change and
mountain plover population trends. However, climate change could
potentially impact the species. According to the IPCC (2007, p. 6),
``warming of the climate system is unequivocal, as is now evident from
observations of increases in global average air and ocean temperatures,
widespread melting of snow and ice, and rising global average sea
level.'' Average Northern Hemisphere temperatures during the second
half of the 20th century were very likely higher than during any other
50-year period in the last 500 years and likely the highest in at least
the past 1,300 years (IPCC 2007, p. 30). It is very likely that over
the past 50 years cold days, cold nights, and frosts have become less
frequent over most land areas, and hot days and hot nights have become
more frequent (IPCC 2007, p. 6). It is likely that heat waves have
become more frequent over most land areas, and the frequency of heavy
precipitation events has increased over most areas (IPCC 2007, p. 30).
Changes in the global climate system during the 21st century are
likely to be larger than those observed during the 20th century (IPCC
2007, p. 19). For the next 2 decades, a warming of about 0.2 degrees
Celsius ([deg]C) (0.4 degrees Fahrenheit ([deg]F)) per decade is
projected (IPCC 2007, p. 19). Afterward, temperature projections
increasingly depend on specific emission scenarios (IPCC 2007, p. 19).
Various emissions scenarios suggest that by the end of the 21st
century, average global temperatures are expected to increase 0.6 to
4.0 [deg]C (1.1 to 7.2 [deg]F), with the greatest warming expected over
land and at most high northern latitudes (IPCC 2007, p. 46).
The IPCC (2007, p. 48) predicts that the resiliency of many
ecosystems is likely to be exceeded this century by an unprecedented
combination of climate change associated disturbances (e.g., flooding,
drought, wildfire, and insects), and other global drivers. Current
climate change predictions for terrestrial areas in the Northern
Hemisphere indicate intense precipitation events, warmer air
temperatures, and increased summer continental winds (Field et al.
1999, pp. 5-10; Cayan et al. 2005, pp. 6-28). With medium confidence,
IPCC predicts that approximately 20 to 30 percent of plant and animal
species assessed so far are likely to be at an increased risk of
extinction if increases in global average temperature exceed 1.5 to 2.5
[deg]C (3 to 5 [deg]F).
The mountain plover is primarily a species of grasslands and semi-
desert. Grasslands in the Great Plains of the United States and
southern Canada are predicted to get warmer and drier with climate
change (North American Bird
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Conservation Initiative 2010, p.18). Southwestern grasslands are
expected to become drier because of declining precipitation and higher
temperatures, especially the Chihuahuan Desert grasslands of the
southwestern United States and northern Mexico, which are critical
wintering areas for many grassland birds, including the mountain plover
(North American Bird Conservation Initiative 2010, p.18). In northern
grasslands, additional precipitation is expected, but they will still
become drier because warmer temperatures will cause increased
evaporation (North American Bird Conservation Initiative 2010, p. 18).
Variability in precipitation is also expected to increase; droughts,
flooding, and extreme storms (such as hailstorms) are all expected to
become more common (North American Bird Conservation Initiative 2010,
p.18). Increased atmospheric carbon dioxide will probably contribute to
invasions of woody shrubs into grasslands (North American Bird
Conservation Initiative 2010, p. 18), which could make certain habitats
unusable for the mountain plover.
Climate Wizard (TNC 2007) predicts an average temperature increase
of approximately 4 to 6 [deg]F by the 2050s for the majority of
mountain plover breeding and wintering habitat within the United
States. Precipitation is projected to decline slightly in the southwest
portion of the range, and to increase by 10 to 15 percent in the more
northern portions of the range in the same time period. However, as
stated above, warmer temperatures and evaporation may offset any gains
in precipitation. By the 2080s, temperatures are predicted to increase
by as much as 7.5 [deg]F within the species' breeding range, and
precipitation to decline from 2050s levels throughout the range (TNC
2007). Weather data in the Imperial Valley recorded by the Desert
Research Institute of the Western Regional Climate Center (WRCC)
between 1927 and 2010 show an increasing trend in average temperature
during the months of September through March, when mountain plover are
present in the area (WRCC 2010a, Figure 1). Projected temperature
change for the Imperial Valley was obtained through the Climate Wizard,
in which an average of all models was used to display change in
temperature. These data indicate a 3.9 [deg]F increase in temperature
for the 2050s and a 5.7 [deg]F increase for the 2080s (TNC 2007). The
WRCC also documented in Imperial, California, a slight increasing trend
in average precipitation (inches) from 1925-2010 (WRCC 2010b).
Projected change in precipitation values for the Imperial Valley was
also obtained through the Climate Wizard in which an average of all
models was used to display percent change in precipitation. These data
indicate a 1.1 percent increase in precipitation for the 2050s and an
increase of 0.3 percent by the 2080s (TNC 2007).
Change in plant phenology (timing of life cycle events such as
vegetative growth and reproduction) may be one of the earliest observed
responses to rapid global climate change and could potentially have
serious consequences both for plants and animals that depend on
periodically available resources (Moza and Batnegar 2005, p. 243). A
change in the timing of availability of insects that mountain plover
and their chicks rely on as a food source could occur as a result in
changes in plant phenology.
Because they are often highly competitive, invasive plant species
are altering the plant composition of ecosystems and changing their
structure and function over large landscape areas. Addition of fine
fuels from these species often increases fire frequency, which can lead
to increased dominance by invasive species and further habitat
degradation. Climate change is exacerbating these changes by altering
the amount and seasonal distribution of precipitation and seasonal
temperature patterns in ways that often favor the invasive species
(Tausch 2008). This could potentially result in changes in the amount
of ground cover in mountain plover habitat, which could discourage
mountain plover nesting. Nonnative wildlife species that could compete
with the mountain plover for resources or prey on the species could
potentially move into their habitats.
Although the mountain plover was not included in ``The State of the
Birds--2010 Report on Climate Change'' (North American Bird
Conservation Initiative), it was assessed using the sensitivity traits
analysis used in that report (Sauer 2010b, pers. comm.). The threat of
climate change impacts to the plover was considered low, as it was only
considered sensitive to one of the five main traits (it was considered
a breeding obligate to a single habitat type) (Sauer 2010b, pers.
comm.). Species that occupy only a single habitat for breeding are
vulnerable should climate change reduce or eliminate that habitat.
While the mountain plover has been often described as a grassland
obligate (i.e., is dependent on grasslands for breeding), it also
breeds in agricultural fields, and in semi-desert habitat. As such, we
believe it is less likely to be threatened by climate change impacting
grassland, or any one of its favored breeding habitats, than is
suggested by its classification as a breeding obligate to a single
habitat type. The mountain plover was not considered sensitive to
potential climate change impacts based on the other four traits (its
migratory habits, dispersal ability, niche specificity, and
reproductive potential) (Sauer 2010b, pers. comm.). In general, the
mountain plover seems to possess characteristics that would allow it to
adapt to changing environmental and climate conditions. See the North
American Bird Conservation Initiative (2010, p. 28) for definitions of
these traits.
Specific information on mountain plover suggests that the species
might be adapted to drought, and that climate change predictions of the
Great Plains becoming warmer and drier might benefit the species
(Dinsmore 2008, p. 52). Andres and Stone (2009, p. 31) predicted
increased summer temperatures and decreased precipitation could benefit
mountain plover breeding. Recruitment of juvenile mountain plover into
the population appears linked to regional patterns of precipitation,
with highest recruitment coming from areas with lowest precipitation
every year, and a subsequent increase in populations of adults observed
from the same areas after a 1- to 2-year lag (Wunder 2007, pp. 119-
121). Annual survival of mountain plover in Montana proved higher
during periods of drought, despite potential reduction in insect foods
(Dinsmore 2008, p. 52). Peterson (2003, pp. 291-292) concluded that
there have been subtle shifts northward in ranges of grassland birds,
including mountain plover, potentially due to climate change.
Climate change predictions are based on models with assumptions,
and there are uncertainties regarding the magnitude of associated
climate change parameters, such as the amount and timing of
precipitation and seasonal temperature changes. There is also
uncertainty as to the magnitude of effects of predicted climate
parameters. The mountain plover, along with its habitat, will likely be
affected in some manner by climate change. A shift in the species'
geographic range may occur due to an increase in temperature and
drought, although climate change would likely not pose as great a risk
to mountain plover habitat as it may to species in polar, coastal, or
montane ecosystems. Nonnative and invasive species, both plants and
animals, could move into plover habitat as a result of
[[Page 27797]]
changes in temperature or precipitation patterns and degrade nesting
habitat or compete with the mountain plover for resources. A change in
the timing of availability of insects that mountain plover and their
chicks rely on as a food source could occur as a result of changes in
plant phenology. There is no information available to suggest that any
of these factors are impacting mountain plover now or that they will
likely impact the species in the foreseeable future.
Based on all the potential climate change factors, a shift in range
of the species could be possible, but there is no information available
to suggest that a net loss in occupied breeding habitat or a
significant impact to the status of the species will result. Although
currently difficult to quantify, changes in climate, including higher
temperatures, increasing stochastic precipitation events, high winds,
and increasing soil dryness, will likely lead to a loss of agricultural
production in the Imperial Valley; however, wintering habitat seems
adequate to support the species. The species is adaptable to a wide
array of climes, as evidenced by a geographic range that includes 12
States, Canada, and Mexico. Based on the best available information on
climate change projections modeled over the next 40 to 70 years, we do
not consider climate change to be a significant threat to the mountain
plover at this time.
Human Disturbance
Knopf and Wunder (2006) stated that mountain plover on nests are
extremely tolerant of human disturbance from vehicles, tractors, and
aircraft, but quickly moved away when approached by a human on foot.
While adult mountain plover would not likely be affected by humans on
foot, eggs left unprotected for a period of time could become
overheated if exposed to direct sun on hot days.
It seems likely that heavy construction activities nearby could
impact nesting mountain plover. Such activities are limited in scope
across mountain plover breeding habitat at any one time. In addition,
timing stipulations that restrict construction related to oil and gas
development, wind-power development, and some other activities in the
vicinity of mountain plover during the nesting season exist for some
Federal lands (Knopf and Wunder 2006).
Mountain plover are only one of a number of breeding bird species
found in the habitats and locations where they nest. While prohibitions
under the MBTA govern direct mortality and the destruction of mountain
plover nests, general awareness of MBTA protections and of efforts to
protect nesting birds, their nests, and their eggs may help limit human
disturbance to nesting mountain plover.
Andres and Stone (2009, p. 27) suggested population-level effects
from human disturbance were unlikely. We conclude that while human-
caused disturbance may impact mountain plover, such impacts are
generally of limited scope, and human disturbance is not likely a
significant threat to the species.
Cumulative Impacts
Some of the threats discussed in this finding could work in concert
with one another to cumulatively create situations that potentially
impact the mountain plover beyond the scope of each individual threat.
For example, as discussed under Factor C, habitat fragmentation,
including energy development that both alters habitat and provides
structure on which predators could perch, could lead to increase in
predation on the mountain plover. We have no data to determine if, or
to what extent, such a scenario is likely to occur. We conclude, at
this time, that it does not present a threat to the future existence of
the mountain plover.
Similarly, under Factor A, we alluded to the potential that in the
Imperial Valley and other areas of California, human development, solar
development, changing agricultural practices, water availability, and
climate change could interact to heighten potential loss of mountain
plover wintering habitat. In the future, warming climate may
necessitate use of more irrigation water for crops at the same time
that water availability decreases due to expansion of human population
and related water demand. In our best judgment, agriculture in the
Imperial Valley, and in other areas of California that support the
mountain plover, are likely to be affected by some variation of the
above scenario. However, specific changes in agriculture are uncertain.
Seasonal change in timing of crops, potential change toward those crops
needing less water, and changes in irrigation practices may or may not
detract from available wintering habitat for mountain plover. While
cumulatively, these factors will likely reduce the total area of
wintering habitat available, we believe that sufficient area of
appropriate agricultural habitat will persist to support wintering
mountain plover.
We have not identified other likely scenarios where the potential
threats discussed in the five factors above have potential to work in
concert to synergistically produce threats to the mountain plover above
those which we have analyzed. We conclude that, at this time, there are
no identifiable cumulative impacts likely to threaten the existence of
the mountain plover in the foreseeable future.
Summary of Factor E
We conclude that the best scientific and commercial information
available indicates that the mountain plover is not now, or likely in
the future, threatened by genetic stochasticity, its typical lifespan,
its site fidelity, exposure to pesticides, selenium toxicity,
grasshopper and cricket control, weather, climate change, or human
disturbance, or cumulative impacts of potential threats such that the
species is in danger of extinction or likely to become so within the
foreseeable future.
Finding
As required by the Act, we considered the five factors in assessing
whether the mountain plover is endangered or threatened throughout all,
or a significant portion of its range. We have carefully examined the
best scientific and commercial information available regarding the
status and past and present and future threats faced by the mountain
plover. We reviewed information in our files, other available published
and unpublished information, and information provided by interested
parties following our February 16, 1999, and December 5, 2002,
proposals to list the mountain plover (64 FR 7587 and 67 FR 72396,
respectively), and following our June 29, 2010, document (75 FR 37353)
vacating our September 9, 2003, withdrawal (68 FR 53083) and
reinstating our 2002 proposal. We also consulted with Federal and State
land managers.
There have been historical impacts to the mountain plover, in
particular the loss of much of the native prairie ecosystem, including
bison, prairie dog colonies, other native grazers, and wildfires that
produced extensive mountain plover habitat on the Great Plains.
However, past concerns regarding continuing and future loss of breeding
habitat provided by black-tailed prairie dog colonies appears
unfounded. Conversion to agriculture remains insignificant across the
mountain plover's breeding range. Human development and resultant
impact to mountain plover breeding habitat in South Park, Colorado, has
not occurred as previously anticipated, and is not expected to do so in
the foreseeable future. Little evidence has
[[Page 27798]]
surfaced to suggest that the mountain plover's substantial use of
cultivated lands for breeding is problematic. The potential for future
energy development to adversely affect mountain plover and their
habitat on their breeding or wintering ranges is not fully known and
requires continued research. However, studies to date do not lead us to
conclude that these activities currently pose substantial threats to
the mountain plover or will in the foreseeable future. Climate change
may impact the mountain plover, positively or negatively, in ways not
yet envisioned.
In the past, we were concerned that mountain plover life span was
short compared to other plovers and that this, in combination with high
breeding site fidelity, presented a threat to breeding populations.
Contrary to our previous belief, the mountain plover is now considered
a relatively long-lived species. Site fidelity and ability to seek out
alternative sites for breeding does not appear to be a concern. Based
on new information regarding life span, site fidelity, and dispersal,
we no longer believe that these aspects of the mountain plover's life
history represent any threat to the species. Lastly, recent information
confirms that some mountain plover are exposed to pesticides, but no
evidence of impacts to individuals, local populations, or rangewide
impacts to the species have been demonstrated.
The current status of the mountain plover does not suggest that
future habitat changes, or the combination of climate change and
habitat changes will result in significant population-level impacts in
the foreseeable future. Their geographically widespread breeding and
wintering locations, and ability to use a variety of habitats,
contribute to their security. During breeding, they utilize short- and
mixed-grass prairie, prairie dog colonies, agricultural lands, and
semi-desert (Dinsmore 2003, pp. 14-17). The variety of habitats in
which they successfully breed suggests that threats affecting one
habitat type would not greatly increase the mountain plover's
vulnerability to extinction. Mountain plover have proven to be
adaptable to many human activities, such as using crop fields for
breeding and wintering, and benefitting from some cattle grazing
practices. Over time, the extent of wintering habitat in California is
likely to decline, but wintering mountain plover exploit a variety of
grassland, rangeland, crop fields, and semi-desert landscapes from the
Gulf Coast to the Pacific Ocean. We conclude that any foreseeable
future declines in wintering habitat, in California or elsewhere, are
unlikely to imperil the mountain plover.
We estimate the current rangewide mountain plover breeding
population to be over 20,000 birds. This is more than double the
estimate of 8,000 to 10,000 mountain plover that we cited in our
December 5, 2002, proposal to list the mountain plover as a threatened
species (67 FR 72396). While we have no evidence that an actual
population increase has occurred, a larger known population provides
added security from current and future potential influences and
threats.
Based on our review of the best available scientific and commercial
information pertaining to the five factors, we find that the threats,
alone or cumulatively, are not of sufficient imminence, severity, or
magnitude to indicate that the mountain plover is in danger of
extinction, or likely to become endangered within the foreseeable
future, throughout all or a significant portion of it range. The
mountain plover has experienced historical losses of native habitat
resulting in a significant decline in the rangewide population.
However, BBS survey results suggest that the recent (1999 through 2009)
rate of decline has moderated (see Population Size and Trends above).
We have no evidence that potential threats (as discussed in Factors A,
B, C, D, and E) are acting on the species or its habitat in a way that
would reverse this positive trend or result in an increased rate of
population decline within the foreseeable future. The currently
estimated rangewide mountain plover population, more than 20,000
breeding birds, is more than double that estimated in 2002, providing
the species with added security should increased threats to its
wellbeing arise. As stated above, the mountain plover's geographically
widespread breeding and wintering ranges, and ability to exploit a
variety of habitats, contribute to its security. According to the Act,
the term ``endangered species'' means any species which is in danger of
extinction throughout all or a significant portion of its range; the
term ``threatened species'' means any species which is likely to become
an endangered species within the foreseeable future throughout all or a
significant portion of its range. We conclude that the mountain plover
does not meet the definition of endangered, because there is an
apparent trend toward stability of the species' rangewide population,
it remains widespread over both its breeding and wintering ranges, and
it can exploit a variety of habitats including areas of human
disturbance. In addition, we have found no threats acting on the
mountain plover in a way that would drive the species towards being
endangered in the foreseeable future; therefore, the species does not
meet the definition of threatened. Therefore, we find that listing the
mountain plover as an endangered or threatened species is not warranted
throughout all or a significant portion of its range at this time (see
the Significant Portion of the Range discussion below). As such, we
withdraw our December 5, 2002, proposed rule (67 FR 72396) to list the
mountain plover as a threatened species.
Distinct Vertebrate Population Segments/Significant Portion of the
Range
After assessing whether the species is endangered or threatened
throughout its range, we next consider whether a distinct vertebrate
population segment (DPS) or whether any significant portion of the
mountain plover range meets the definition of endangered or is likely
to become endangered in the foreseeable future (threatened).
Distinct Vertebrate Population Segment
Under the Service's Policy Regarding the Recognition of Distinct
Vertebrate Population Segments Under the Endangered Species Act (61 FR
4722, February 7, 1996), three elements are considered in the decision
concerning the establishment and classification of a possible DPS.
These are applied similarly for additions to or removal from the
Federal List of Endangered and Threatened Wildlife. These elements
include:
(1) The discreteness of a population in relation to the remainder
of the species to which it belongs;
(2) The significance of the population segment to the species to
which it belongs; and
(3) The population segment's conservation status in relation to the
Act's standards for listing, delisting, or reclassification (i.e., is
the population segment endangered or threatened).
Discreteness
Under the DPS policy a population segment of a vertebrate taxon may
be considered discrete if it satisfies either one of the following
conditions:
(1) It is markedly separated from other populations of the same
taxon as a consequence of physical, physiological, ecological, or
behavioral factors. Quantitative measures of genetic or morphological
discontinuity may provide evidence of this separation.
(2) It is delimited by international governmental boundaries within
which differences in control of exploitation, management of habitat,
conservation
[[Page 27799]]
status, or regulatory mechanisms exist that are significant in light of
section 4(a)(1)(D) of the Act.
We do not consider any population segment of mountain plover to be
markedly separated from other populations of the same taxon as a
consequence of physical, physiological, ecological, or behavioral
factors. Mountain plover are naturally distributed across a large
landscape in a discontinuous fashion. Available breeding and wintering
habitats exist in a constantly shifting mosaic of suitable habitat
throughout the western Great Plains and Rocky Mountain States from
Canada to Mexico. As an avian species, mountain plover are able to move
long distances during migration, and to return to different
geographical areas for breeding or wintering.
Although there is some evidence that mountain plover exhibit some
site fidelity to their breeding areas (Graul 1973, p. 71; Skrade and
Dinsmore 2010, p. 672), other studies have shown that the species can
disperse over relatively long distances (Knopf and Wunder 2006; Bly
2010b, pers. comm.). There are no known barriers to movement throughout
the geographic range of the species. Wunder (2007, p. 118) concluded
that there is widespread mixing of mountain plover populations in
winter and that birds may use alternate wintering sites in different
years. A genetic study using nuclear microsatellites concluded that
mountain plover across sampled breeding locations in Colorado and
Montana comprised a single, relatively homogenous gene pool (Oyler-
McCance et al. 2008, pp. 496-497). Results suggested that there was
sufficient gene flow among breeding areas to offset genetic effects of
small populations and reported adult fidelity to breeding areas (Oyler-
McCance et al. 2008, pp. 496-497).
The mountain plover spans international boundaries between the
United States, Canada, and Mexico; however, the vast majority of
occupied breeding habitat occurs in the United States with few breeding
records in Canada and Mexico. Mexico likely winters a substantial
number of mountain plover that breed in the United States. The known
relative distribution of mountain plover between the three countries
has remained fairly constant in recent years. Additionally, we are not
aware of any differences in control of exploitation, management of
habitat, conservation status, or regulatory mechanisms that exist in
Canada or Mexico that are significant in light of section 4(a)(1)(D) of
the Act (the inadequacy of existing regulatory mechanisms). Therefore,
we do not believe that international boundaries provide evidence of
discrete mountain plover populations.
We determine, based on a review of the best available information,
that no mountain plover population segments meet the discreteness
conditions of the 1996 DPS policy. Therefore, no mountain plover
population segment qualifies as a DPS under our policy, and no DPS is a
listable entity under the Act.
The DPS policy is clear that significance is analyzed only when a
population segment has been identified as discrete. Because we found
that no mountain plover populations meet the discreteness element and,
therefore, do not qualify as a DPS under the Service's DPS policy, we
will not conduct an evaluation of significance.
Significant Portion of the Range
The Act defines an endangered species as one ``in danger of
extinction throughout all or a significant portion of its range,'' and
a threatened species as one ``likely to become an endangered species
within the foreseeable future throughout all or a significant portion
of its range.'' The term ``significant portion of its range'' is not
defined by the statute. For the purposes of this finding, a significant
portion of a species' range is an area that is important to the
conservation of the species because it contributes meaningfully to the
representation, resiliency, or redundancy of the species. The
contribution must be at a level such that its loss would result in a
significant decrease in the viability of the species.
If an analysis of whether a species is endangered or threatened in
a significant portion of its range is appropriate, we engage in a
systematic process that begins with identifying any portions of the
range of the species that warrant further consideration. The range of a
species can theoretically be divided into portions in an infinite
number of ways. However, there is no purpose in analyzing portions of
the range that are not reasonably likely to be significant and
endangered or threatened. To identify only those portions that warrant
further consideration, we determine whether there is substantial
information indicating that (i) the portions may be significant and
(ii) the species may be in danger of extinction there or likely to
become so within the foreseeable future. In practice, a key part of
this analysis is whether the threats are geographically concentrated in
some way. If the threats to the species are essentially uniform
throughout its range, no portion is likely to warrant further
consideration. Moreover, if any concentration of threats applies only
to portions of the range that are unimportant to the viability of the
species, such portions will not warrant further consideration.
We next address whether any portions of the mountain plover's range
warrant further consideration. On the basis of our review, we found no
geographic concentration of threats on breeding or wintering habitat
such that the subspecies may be in danger of extinction in that
portion. Although the mountain plover's wintering habitat in California
is likely to decrease in the future because of changes in land use and
agriculture, we have determined that the likely extent of change will
not result in a significant threat to the species' ability to maintain
a wintering population in California. Similarly, we found that there is
no area within the breeding range of the mountain plover where the
potential threat of changes to habitat are concentrated or may be
substantially greater than in other portions of the range. The factors
affecting the species are essentially uniform throughout its range,
indicating that no portion of the mountain plover's range warrants
further consideration of possible endangered or threatened status.
We request that you submit any new information concerning the
status of, or threats to, the mountain plover to our Colorado
Ecological Services Office (see ADDRESSES) whenever it becomes
available. New information will help us monitor the mountain plover and
encourage its conservation. If an emergency situation develops for the
mountain plover or any other species, we will act to provide immediate
protection.
References Cited
A complete list of references cited is available on the Internet at
http://www.regulations.gov and upon request from the Colorado
Ecological Services Office (see ADDRESSES).
Authors
The primary authors of this document are the staff members of the
Colorado Ecological Services Office (see ADDRESSES).
Authority
The authority for this section is section 4 of the Endangered
Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).
Dated: April 29, 2011.
Rowan W. Gould,
Acting Director, Fish and Wildlife Service.
[FR Doc. 2011-11056 Filed 5-11-11; 8:45 am]
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