[Federal Register: March 6, 2002 (Volume 67, Number 44)]
[Rules and Regulations]
[Page 10101-10113]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr06mr02-3]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
RIN 1018-AG04
Endangered and Threatened Wildlife and Plants; Endangered Status
for the Buena Vista Lake Shrew (Sorex Ornatus Relictus)
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Final rule.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), determine
endangered status pursuant to the Endangered Species Act of 1973, as
amended (Act), for the Buena Vista Lake shrew (Sorex ornatus relictus).
This subspecies is endemic to Kern County, California, and is currently
known from only four locations. This subspecies is imperiled primarily
by habitat loss and modification due to agricultural activities,
unnatural 1 hydrological conditions, incompatible water management
practices, the possible toxic effects of selenium poisoning,
modification or loss of genetic integrity from introgression
(hybridization), and the loss of populations caused by random naturally
occurring events. This final rule extends the Federal protection and
recovery provisions of the Act for the Buena Vista Lake shrew.
DATES: This final rule is effective April 5, 2002.
ADDRESSES: The complete file for this rule is available for public
inspection, by appointment, during normal business hours at the
Sacramento Fish and Wildlife Office, U.S. Fish and Wildlife Service,
2800 Cottage Way, Rm W-2605, Sacramento, CA 95825-1888.
FOR FURTHER INFORMATION CONTACT: Jan Knight, Chris Nagano, or Dwight
Harvey, Sacramento Fish and Wildlife Office, at the above address
(telephone 916/414-6600; facsimile 916/414-6710).
SUPPLEMENTARY INFORMATION:
Background
The Buena Vista Lake shrew (Sorex ornatus relictus) is one of nine
subspecies of ornate shrew, eight of which are known to occur in
California (Hall 1981; Owen and Hoffmann 1983; Maldonado 1992; Wilson
and Reeder 1993; Jesus Maldonado, University of California-Los Angeles,
in litt. 2000). Ornate shrews belong to the family Soricidae (long-
tailed shrews) in the order Insectivora (Hall 1981; Junge and Hoffmann
1981; Owen and Hoffmann 1983; George 1988; Churchfield 1990). There are
27 species in the genus Sorex, and they are distributed throughout a
large portion of North and Central America (Jackson 1928; Repenning
1967; Corbet and Hill 1980; Hall 1981; Churchfield 1990).
Shrews are primarily insectivorous mammals about the size of a
mouse. They vary in color from black or brown, to grey, have long
pointed snouts, five toes on each foot, tiny bead-like eyes, soft fur,
visible external ears, and a scaly, well-developed tail covered with
very short hairs (Ingles 1965; Vaughan 1978; Jamerson and Peeters 1988;
Churchfield 1990). Shrews are active during the day and night but are
rarely seen due to their small size and cryptic behavior. A few species
of shrews can enter a daily state of inactivity (torpor) under extreme
environmental conditions (Ingles 1965; Churchfield 1990), such as very
low ambient temperatures. Shrews do not hibernate.
Grinnell (1932) was the first to describe the Buena Vista Lake
shrew. According to Grinnell's description, the Buena Vista Lake
shrew's back is predominantly black with a buffy-brown speckling
pattern, its sides are more buffy-brown than the upper surface, and its
underside is smoke-gray. The tail is faintly bicolor and blackens
toward the end. The Buena Vista Lake shrew weighs approximately 4 grams
(0.14 ounces) (Kathy Freas, Stanford University, pers. comm., 1994) and
has a total length ranging from 98 to 105 millimeters (mm) (3.85 to
4.13 inches (in)) with a tail length of 35 to 39 mm (1.38 to 1.54 in)
(Grinnell 1932). The Buena Vista Lake shrew differs from its
geographically closest subspecies, the Southern California ornate shrew
(Sorex ornatus spp. ornatus), by having darker, grayish-black
coloration, rather than brown. In addition, the Southern California
ornate shrew has a slightly larger body size; shorter tail; skull with
a shorter, heavier rostrum (snout); and a higher, more angular brain-
case in dorsal (top) view (Grinnell 1932).
Shrews have a high rate of metabolism because of their small size
(Newman and Rudd 1978; McNab 1991). They lose heat rapidly from the
surface of their small bodies, and are continually faced with the
problem of getting enough food to maintain their body temperatures,
especially in cold conditions (Aitchison 1987; Genoud 1988). Shrews
feed indiscriminately on the available larvae and adults of several
species of aquatic and terrestrial insects, some of which are
detrimental to agricultural crops (Holling 1959; Ingles 1965; Newman
1970; Churchfield 1990). They are also known to consume spiders,
centipedes, slugs, snails, and earthworms (Jamerson and Peeters 1988)
on a seasonally available basis (Aitchison 1987).
Little is known about the reproduction or longevity of Buena Vista
Lake shrews. Shrews, on the average, rarely live more than 12 months,
and each generation is largely replaced annually (Rudd 1955b). For
Buena Vista Lake shrews, the breeding season begins in February or
March, and ends with the onset of the dry season in May or June, or may
extend later in the
[[Page 10102]]
year, based on habitat quality and availability of water (J. Maldonado,
pers. comm., 1998; Paul Collins, Santa Barbara Museum of Natural
History, in litt. 2000). It is likely that this subspecies, like other
long-tailed shrews, can give birth to two litters of four to six young
each per year; the number of litters is usually dependent on how early
or late in the year the young are born, and how soon they become
sexually active (Rudd 1955b; Owen and Hoffmann 1983).
A taxonomic study of North American shrews noted that what little
geographic variation exists in long-tailed shrew subspecies, like the
Buena Vista Lake shrew, is measured in their pelage (coat) paleness or
darkness; in their size, both external and cranial; in tail length; in
general shape of the skull; and in dentition (size of teeth and length
of molar tooth row) (Jackson 1928). Long-tailed shrews all have simply
colored gray or brown fur without distinct patterns, and the general
shape and proportions of skulls are fairly constant, varying little
except between widely separated populations (Jackson 1928). However,
long-tailed shrew pelage color can vary from fading or rusting due to
wear, and the color and length can show pronounced seasonal variation
(Ivanter 1994). Although no sexual variation or age variation in pelage
color exists, seasonal variation between summer and winter color and
hair length varies markedly in long-tailed shrews, with winter fur more
grayish but paler in summer (Jackson 1928). In addition, skull size
measurements can vary from 5 to 7.5 percent from the average, and this
variation is also noted in external measurements of total length, tail
length, and hind foot length. Tooth patterns and skull sizes can also
show variation within shrew species.
Populations of ornate shrews show a great degree of variation in
size and pelage coloration, and some populations exhibit different
degrees of melanism (different shades of black caused by environmental
exposure) (Rudd 1955a; Hays 1990; Maldonado et al. 2001). Therefore, to
identify shrew subspecies based solely on pelage color may not always
be reliable (Maldonado et al. 2001). However, recent studies involving
the taxonomic characters of North American shrews have focused on
detailed studies of their skull, teeth, chromosomes, allozymes, and
gene sequences because other taxonomic characters can be less reliable
(George 1986, 1988; Churchfield 1990; Ivanitskaya 1994; Carraway 1990,
1995; Maldonado et al. 2001). In a study on cranial morphology
measuring skulls and teeth to assess the relationships and patterns of
geographic variation of the ornate shrews, Maldonado (in press)
concluded that populations of ornate shrews throughout their range
showed low levels of morphological divergence. In addition, variation
in these skull measurements due to age or sex was shown not to be
significant.
Despite their phenotypic uniformity (similar appearance), ornate
shrew populations have surprisingly high levels of genetic divergence
(separation) which could prove useful for explaining the evolutionary
history of their relationships (Maldonado et al. 2001). Recent genetic
evaluations have been done on the ornate shrew complex (consisting of
nine subspecies, seven of which only occur in California, one occurs in
California and Baja California and one subspecies only occurs in Baja
California) using mitrochondrial deoxyribonucleic acid (DNA) sequencing
of the cytochrome b gene and protein allozymes (Maldonado et al. 2001).
From these data, researchers determined that the ornate shrew complex
is geographically structured into three haplotype clades (genetic
groups) representing southern, central, and northern localities within
California. From this genetic analysis, samples obtained from
individual subspecies can be accurately identified within and between
these three clades. However, genetic and morphological data on ornate
shrews do not show the same level of sensitivity for differentiating
individuals to the subspecies level. Using morphological data from the
same subspecies, only 50 percent or less of the Buena Vista Lake shrews
could be identified to the correct subspecies (Maldonado (in press)).
At the subspecific level, Maldonado's (in press) morphological data can
be used to distinguish between the three genetic clades but not within
them. These results demonstrate the importance of evaluating both
morphological and genetic data, when available, to evaluate and
identify shrews captured within the range of the Buena Vista Lake
shrew.
The Buena Vista Lake shrew formerly occurred in wetlands around
Buena Vista Lake, and presumably throughout the Tulare Basin (Grinnell
1932, 1933; Hall 1981; Williams and Kilburn 1984; Williams 1986;
Service 1998). The animals were likely distributed throughout the
swampy margins of Kern, Buena Vista, Goose, and Tulare Lakes. By the
time the first Buena Vista Lake shrews were collected and described,
these lakes had already been drained and mostly cultivated with only
sparse remnants of the original flora and fauna (Grinnell 1932; Mercer
and Morgan 1991; Griggs 1992; Service 1998).
Nearly all of the valley floor in the Tulare Basin is cultivated,
and most of the lakes and marshes have been drained and cultivated
(Williams 1986; Werschkull et al. 1992; Williams and Kilburn 1992;
Williams and Harpster 2001). The great expansion and conversion of
natural lands and pasture to irrigated orchards, vegetable crops,
cotton, and dairies was made possible by large increases in ground
water pumping and the Central Valley Project's delivery of northern
California water to the San Joaquin Valley (Mercer and Morgan 1991).
The Buena Vista Lake shrew is now known from four isolated locations
along an approximately 113-kilometer (km) (70-mile (mi)) stretch on the
west side of the Tulare Basin. The four locations are the former Kern
Lake Preserve (Kern Preserve) on the old Kern Lake bed, the Kern Fan
recharge area, Cole Levee Ecological Preserve (Cole Levee), and the
Kern National Wildlife Refuge (Kern NWR).
Buena Vista Lake shrews prefer moist habitat that has a diversity
of terrestrial and aquatic insect prey (Kirkland 1991; Ma and Talmage
2001). During surveys conducted in 1988 and 1990 on the Kern Preserve,
Freas (1990) found that shrews were more abundant in moderately mesic
(moister) habitats versus xeric (drier) habitats, with 25 animals being
captured in the moister environments and none in the drier habitat.
Maldonado (1992) also found shrews at the Kern Preserve to be closely
associated with dense, riparian understories that provide food, cover,
and moisture. Capture of two Buena Vista Lake shrews at the Kern NWR
occurred in a 0.46-hectare (ha) (1.13-acre (ac)) area that contained
the most undisturbed moist riparian habitat, with a mature tree
overstory, abundant invertebrates, and ground cover totaling about 90-
95 percent (Maldonado et al., 1998; J. Maldonado, in litt. 1998).
The mesic, lower elevation range of the Buena Vista Lake shrew is
almost completely surrounded by the semiarid, higher elevation range of
the Southern California ornate shrew (Hall 1981; J. Madonado, in litt.
1998, in press; Maldonado et al. 2001). Grinnell (1932) noted that
Southern California ornate shrews occupied the uplands along streamside
habitat, and intergraded with the lowland Buena Vista Lake shrews along
the lower courses of the streams that enter the Kern-Tulare basin.
Due to the scarcity of Buena Vista Lake shrews, data about their
home range size, breeding territory size, and population densities are
lacking. Except
[[Page 10103]]
for the breeding season, shrews in general are solitary. As juveniles,
they establish their home range, which is a small area in which they
nest, forage, and explore, and where they remain for most of their life
(Churchfield 1990). Accurate estimation of home range size based on
mark and recapture techniques requires that a minimal number of
recaptures be made (Hawes 1977). This level of data has never been
collected for Buena Vista Lake shrews and, therefore, their home range
has not been determined. Ingles (1961) was able to calculate an average
home range size in a closely related species, the vagrant shrew (Sorex
vagrans), found in the Sierra Nevada of California. The average home
range size was approximately 372 square meters (m2) (4,000
square feet (ft2)), with breeding males occupying larger
territories than breeding females (Hawes 1977). The distribution, and
size, of a shrew's territory varies, and is primarily influenced by the
availability of food (Ma and Talmage 2001). In a study on population
densities of vagrant shrews in western Washington, Newman (1976)
calculated densities of 25.8 shrews/ha (10.1/ac) in the fall and
winter, and 50.2 shrews/ha (20.32/ac) at the height of summer.
At the time we published the proposed rule to list the Buena Vista
Lake shrew (65 FR 35033, June 1, 2000), the only known extant (still
existing) population was located on the Kern Preserve, which is a
privately owned property (California Natural Diversity Data Base 1986;
Jack Allen, Service, in litt. 2000). This property totals about 34 ha
(83 ac) and was presumed, at the time, to support the only surviving
population of Buena Vista Lake shrews.
Since the proposed rule was published, staff from the University of
California at Los Angeles reported the results of additional surveys
for the Buena Vista Lake shrew (J. Maldonado, in litt. 1998; Maldonado
et al. 1998). Two Buena Vista Lake shrews were trapped on the south
side of the Kern NWR in September 1998 (J. Maldonado, in litt. 1998;
Maldonado et al. 1998). Due to the low amount of morphological
variation in ornate shrews as discussed above, and the potential for
the introgression with the southern California ornate shrew, genetic
analysis of the potential Buena Vista Lake shrew specimens was
completed. Tissue samples taken from shrews from the Kern Preserve and
the Kern NWR were genetically analyzed and found distinct from other
ornate shrew populations from California and Baja California. These
specimens were determined to be Buena Vista Lake shrews (Maldonado et
al. 2001; Jesus Maldonado, Smithsonian National Museum, pers. comm.,
2001).
In February and March of 1999, the California State University
Stanislaus Foundation's Endangered Species Recovery Program (ESRP)
surveyed six locations within the historic range of the subspecies
(Williams and Harpster 2001). They reported capturing five shrews at
the Kern NWR along levee roads less than 1.2 km (0.5 mi) from the
location where shrews were captured in 1998 (ESRP 1999a). In March
1999, ESRP found nine more shrews along the banks of an artificial pond
adjacent to the nature center at the Cole Levee, and five more at the
Kern County's water recharge area along the Kern Fan (ESRP 1999b;
Williams and Harpster 2001). To date, no genetic analysis has been done
on these shrews.
Before the 1998 and 1999 surveys, staff of the Kern NWR reported
Buena Vista Lake shrews three other times. In 1992, one shrew was found
alive under a sprinkler cover, and another was found dead in a
manager's residence at the Kern NWR (Morgan Cook, Service, pers. comm.,
1995). One additional shrew was found dead in 1994 within the same
residence on the Kern NWR. This residence is currently the Kern NWR
headquarters and is one of two buildings located on a 4-ha (10-ac)
compound surrounded by lawns and trees (J. Allen, pers. comm., 1998).
The constant lawn, shrub, and tree watering and the ponds at the Kern
NWR headquarters may have been sufficient to maintain a shrew
population (Engler 1994). Although genetic analysis of these specimens
to determine their subspecific identity was not performed, these
reports prompted the surveys for Buena Vista Lake shrews at the Kern
NWR.
The seven shrews captured on the south side of the Kern NWR during
the 1998 and 1999 surveys were located around a 323-ha (800-ac) marsh
with emergent vegetation and an overstory of willows and cottonwoods
(Maldonado et al., 1998; J. Maldonado, in litt. 1998; ESRP 1999a).
These marsh areas remain moist longer than most other marshes on the
Kern NWR (J. Allen, pers. comm., 1998). However, water management
practices at the Kern NWR have focused on waterfowl (Service 1986), and
riparian habitat has not received adequate water over the years to
maintain riparian diversity (Engler 1994; U.S. Bureau of Reclamation
(BOR) 2000).
Over the last 20 years, a number of surveys have taken place in
other fresh water marshes and moist riparian areas on private and
public lands throughout the range of the subspecies and were all
unsuccessful in capturing any Buena Vista Lake shrews. These surveys
include: The Nature Conservancy's (TNC) Paine Wildflower Preserve and
the Voice of America site west of Delano (Clark et al. 1982); along the
Kern River Parkway in 1987 (Beedy et al. 1992); the Tule Elk State
Reserve (Maldonado 1992); the Goose Lake Slough area of the Semitropic
ground water banking project, Kern Water District, Kern County (Germano
and Tabor 1993); Pixley National Wildlife Refuge in Tulare County
(Williams and Harpster 2001); Lake Woollomes in Kern County; and Buena
Vista Lake Aquatic Recreation area at the northern portion of the
former Buena Vista Lake bed, Kern County (ESRP 1999c; Williams and
Harpster 2001).
Other remnant patches of wetland and riparian communities within
the Tulare Basin have not been surveyed and may support the Buena Vista
Lake shrew, including the City of Bakersfield's water recharge area
near the terminus of the Kern River at Buena Vista Lake (J. Maldonado,
in litt. 1998; Service 1998; Williams and Harpster 2001; Bill
Vanherweg, biological consultant, pers. comm., 2001); Goose Lake and
Jerry Slough, overflow channels of the Kern River, located 10 miles
south of Kern NWR, owned and managed by the Semitropic Water District
as a ground water recharge basin (Germano and Tabor 1993); and the
privately owned Crighton Ranch, located near the eastern shore of
historical Tulare Lake in Tulare County (Williams and Harpster 2001).
Privately owned lands that may support Buena Vista Lake shrews are
located around Sand Ridge flood basin, Buena Vista Slough, Goose Lake
and Goose Lake Slough, Creighton Ranch, and along the Kern River west
of Bakersfield, California (J. Maldonado, in litt. 1998, pers. comm.,
1998; Service 1998; Williams and Harpster 2001). The small habitat
patches within these areas would not likely support a significant
number of animals (J. Maldonado, pers. comm., 1998; B. Vanherweg, pers.
comm., 2001). In addition, these areas represent highly disjunct and
fragmented habitat that may not be reconnected to other areas
containing suitable habitat in the foreseeable future.
Previous Federal Action
We included the Buena Vista Lake shrew as a Category 2 candidate
species in the September 18, 1985, Notice of Review (50 FR 37958).
Category 2 species were those for which we had information indicating
that threatened or endangered status might be warranted, but for which
adequate data
[[Page 10104]]
on biological vulnerability and threats were not available to support
issuance of listing proposals.
We received a petition dated April 18, 1988, from Ms. Doris Dixon
of The Interfaith Council for the Protection of Animals and Nature to
list the Buena Vista Lake shrew and three other shrew species as
endangered species. We determined that the petition presented
substantial information that the requested action may be warranted, and
announced our finding in the Federal Register on December 30, 1988 (53
FR 53030). The Buena Vista Lake shrew remained a Category 2 candidate
in the January 6, 1989, Candidate Notice of Review (54 FR 554). In the
November 21, 1991, Notice of Review (56 FR 58804), the Buena Vista Lake
shrew was elevated to Category 1 status based on new information that
we received. Category 1 taxa were those for which we had on file
sufficient information on biological vulnerability and threats to
support the preparation of a listing proposal. In the February 28,
1996, Notice of Review (61 FR 7596), we discontinued the use of
multiple candidate categories and considered the former Category 1
candidates as simply ``candidates'' for listing purposes. The Buena
Vista Lake shrew remained a candidate with a listing priority number of
6 based upon our Listing and Recovery Priority Guidelines (48 FR
43096). The subspecies was elevated to a listing priority number of 3
in the Notice of Review (62 FR 49398) on September 19, 1997, and
retained this listing priority number in the October 25, 1999, Notice
of Review (64 FR 57534), and October 30, 2001, Notice of Review (66 FR
54808).
On June 1, 2000, we published a proposal to list the Buena Vista
Lake shrew as endangered (65 FR 35033) and opened a 60-day comment
period. On August 14, 2000 (65 FR 49530), we reopened the comment
period for an additional 60 days to provide the public another
opportunity to comment on the proposed rule. The final rule for the
subspecies was delayed because nearly the entire Fiscal Year 2001
Listing Program appropriation had to be committed to listing actions
required under court order or settlement agreement, which did not
include the Buena Vista Lake shrew, and essential program management
activities.
On October 2, 2001, we entered into a consent decree to settle
listing litigation with the Center for Biological Diversity, Southern
Appalachian Biodiversity Project, Foundation for Global Sustainability,
and the California Native Plant Society. This consent decree requires
us to make final listing decisions for a number of species we had
previously proposed for listing, including the Buena Vista Lake shrew.
The consent decree requires us to publish a final listing determination
for this subspecies in the Federal Register by March 1, 2002 (Center
for Biological Diversity, et al. v. Norton, Civ. No. 01-2063 (JR)
(D.D.C.)). This final rule reflects new information concerning
distribution, status, and threats to the subspecies since publication
of the proposed rule, and is made in accordance with the aforementioned
agreement.
Summary of Comments and Recommendations
In the June 1, 2000, proposed rule (65 FR 35033), we requested all
interested parties to submit factual reports or information that might
contribute to the development of a final listing decision. We contacted
appropriate Federal agencies, State agencies, county and city
governments, scientists, and other interested parties to request
information and comments. We solicited independent review of the
proposed rule from five peer reviewers. We published legal notices in
the Bakersfield Californian on August 23, 2000. The first comment
period was open for 60 days and closed on July 31, 2000. We reopened a
second comment period on August 14, 2000, for an additional 60 days,
closing on October 13, 2000 (65 FR 49530). We did not receive any
requests for a public hearing during either comment period.
We received eleven comment letters, including four letters from
peer reviewers. Four of the comment letters supported the proposal, one
provided neutral comments, and seven were opposed to the proposal.
Several commenters provided additional information that, with other
clarifications, has been incorporated into the sections titled
``Background'' and ``Summary of Factors'' of this final rule.
Comments of a similar nature or point regarding the proposed rule
have been grouped into issues and are discussed below.
Issue 1: Several commenters questioned whether the Buena Vista Lake
shrew was a valid subspecies. Another commenter believed that the
original description by Grinnell (1932) used ``primitive'' taxonomic
standards, such as skin and skull measurements, to originally describe
this subspecies, and that more current genetic and biogeographical
research is needed before the taxa can be considered valid.
Our Response: In general, we recognize taxonomic determinations
that are published in peer-reviewed journals and are accepted by the
scientific community. The description of the Buena Vista Lake shrew was
published in the University of California Publications in Zoology
(Grinnell 1932). Grinnell described the subspecies based on
distinguishing morphological characteristics, geographical and habitat
distribution, and other taxonomic characteristics. Maldonado (in litt.
2000, in press) stated that the Buena Vista Lake shrew appears to be
morphologically divergent from other populations of ornate shrew in
California. No papers published in peer-reviewed scientific journals
have synonymized the Buena Vista Lake shrew. Based on the most current
scientific information, we have concluded the Buena Vista Lake shrew
represents a valid subspecies.
Issue 2: Several commenters said that unpublished data was used
that was not in the administrative record, and this information was
used to make the determination that the Buena Vista Lake shrew was a
valid subspecies and therefore appropriate for listing under the Act.
Our Response: The original description of the Buena Vista Lake
shrew published by Grinnell (1932) is still the only peer-reviewed,
published taxonomic treatment that is scientifically valid. Unpublished
data regarding the validity of this subspecies would be considered
speculative. Recent unpublished genetic and morphological work done on
ornate shrews did not address the taxonomic validity of the Buena Vista
Lake shrew as a subspecies of ornate shrew, and no scientific papers
pertaining to the taxonomic status of this subspecies were available
during the preparation of either the proposed rule or this final rule.
Issue 3: Several commenters said that we failed to use survey
information made available that showed the presence of Buena Vista Lake
shrews in several locations outside the only reported location at the
former Kern Preserve, and this new information constitutes sufficient
reason not to make the proposed rule final, or to postpone the final
rule until more information can be gathered and assimilated.
Our Response: All survey data received prior to the publication of
the proposed rule was evaluated . We received survey reports that
indicated that Buena Vista Lake shrews were trapped at other areas
outside the known location on the Kern Preserve before publication of
the proposed rule, but did not include this information at that time.
We felt that, due to the
[[Page 10105]]
difficulty in differentiating between subspecies of ornate shrews, and
the possibility of introgression by the Southern California ornate
shrew, it was necessary to obtain additional genetic information to
determine if these new areas supported the Buena Vista Lake shrew
subspecies.
Since publication of the proposed rule, we now believe that, based
on survey efforts, the Buena Vista Lake shrew occurs in four locations,
which are the Kern Preserve, the Kern Fan recharge area, Cole Levee,
and the Kern NWR. We also believe that sufficient threats to the
subspecies continue throughout its range to warrant listing (see the
discussion under Summary of Factors).
Issue 4: Several commenters believe that the administrative record
for the proposed rule was incomplete and unavailable for public review.
Our Response: The complete files for the proposed rule have been,
and are, available for public inspection, by appointment, during normal
business hours at the Sacramento Fish and Wildlife Office (see the
ADDRESSES section).
At the time the proposed rule was published, we received a Freedom
of Information Act request for the administrative record of the
proposed rule. During the preparation of these documents, we noticed
that an edit had been made to the rule and a citation had been left in
that no longer had context. This discrepancy between the references
cited in the published rule and the actual citations used to support
the statement was corrected in the organization of the administrative
record. All citations and references used in the proposed rule were
made available in the public record and the correction to the
administrative record did not change the results of the analysis in the
proposed rule.
Issue 5: One commenter felt that the peer review process should
take place during the proposed rule and not for the final rule, and
that the proposed rule lacked proper peer review.
Our Response: During the preparation of the proposed rule, we
contacted species experts to gather the best scientific and commercial
information available. In accordance with our July 1, 1994 (59 FR
34270), Interagency Cooperative Policy on Peer Review, we also
requested the expert opinions of five independent specialists regarding
the biological and ecological information about the Buena Vista Lake
shrew contained in the proposed rule. The peer review process occurred
during the public comment period of the proposed rule. Therefore, the
scientific community, as well as the public, had an opportunity to
review the proposed rule and provide us comments on it. We believe that
this process allowed ample time for review and comment. Comments by the
public and peer reviewers have been addressed in this final rule.
Issue 6: Several commenters expressed their concern that we did not
use the best scientific and commercial information available.
Our Response: We thoroughly reviewed all available scientific and
commercial data in preparing the proposed and final rules. We sought
and reviewed historic and recent publications and unpublished reports
concerning the Buena Vista Lake shrew, as well as literature
documenting the decline of natural habitats in the San Joaquin Valley
in general. We considered all types of available information in making
a listing determination. This includes reliable unpublished reports,
historical documentation, and personal communications with experts. The
public reviewed our proposed rule, which also was peer-reviewed
according to our policy (see ``Peer Review'' section). We used our best
professional judgment and based our decision on the best scientific and
commercial data available, as required by section 4(b)(1) of the Act.
Issue 7: One commenter said that we failed to comply with the
National Environmental Policy Act (NEPA).
Our Response: We need not prepare environmental assessments or
environmental impact statements pursuant to the NEPA for reasons
outlined in the Federal Register on October 25, 1983 (43 FR 49244).
Listing decisions are based on biological, not sociological or economic
considerations. This view was upheld in the court case Pacific Legal
Foundation v. Andrus, 657 F.2d 829 (1981).
Issue 8: One commenter claimed that the selenium data used in
support of the proposed rule is unsupportable and flawed.
Our Response: While we agree that there has never been a strongly
documented case of selenium poisoning in a wild population of shrews,
the selenium levels measured in the shrew populations found at the
Kesterson National Wildlife Refuge (Kesterson) and the Westlands sites
in Fresno approach or exceed selenium concentrations that can have
chronic deleterious effects on reproduction and other physiological
processes in small mammals. In addition, these same populations of
shrews at Kesterson have declined dramatically over the past 10 years.
While the shrews found at Kesterson are not Buena Vista Lake shrews, we
believe because of the elevated levels of selenium found in portions of
the ecosystem, and in some wildlife inhabiting the Tulare Basin,
selenium poisoning is a potential threat to the Buena Vista Lake shrew.
Issue 9: One commenter felt that if the Buena Vista Lake shrew was
listed, then restrictions would follow for chemical applications, water
storage and conveyance activities, and general farming and ranching
activities.
Our Response: All chemical applications used in regular farming
activities are monitored by the California State Board of Pesticide
Regulation (Pesticide Board) and are subject to their control. We do
advise the Pesticide Board from time to time in regards to the
potential harmful effects certain chemicals may have on endangered and
threatened species if they are exposed, and make recommendations on how
to eliminate or reduce adverse effects to listed species. Water storage
and conveyance systems are subject to local control and through
contracts with the Federal and State governments through the BOR. Where
there is a Federal nexus (activities that are authorized, funded, or
carried out by the Federal Government), certain activities involving
chemical application, water storage or conveyance, and land conversion
may be modified to protect listed species.
Issue 10: One commenter said that we failed to contact or consult
with State and local county governments during the development of the
proposed rule.
Our Response: During the preparation of the proposed and final
rules, we contacted and made available all references and documents to
appropriate State and local government agencies through direct contact,
mailings, and the publication of a legal notice in a local newspaper. A
copy of the proposed rule was sent to the California Department of Fish
and Game (CDFG), Kern County, and other local agencies.
Peer Review
In accordance with our policy published on July 1, 1994 (59 FR
34270), Interagency Cooperative Policy on Peer Review, we solicited the
expert opinions of five independent specialists regarding the
biological and ecological information about the Buena Vista Lake shrew
contained in the proposed rule. The purpose of such review is to ensure
that listing decisions are based on scientifically sound data,
assumptions, and analysis. We received comments
[[Page 10106]]
back from four of the reviewers. All four peer reviewers provided
information meant to correct, clarify, or support statements contained
in the proposed rule. Three reviewers stated that the proposed rule was
an accurate summary of the species biology and status. Two of the
reviewers felt that additional surveys should be done in suitable
habitat for Buena Vista Lake shrews; one of these reviewers felt that
additional surveys and improved management of known populations of the
species could eliminate the need to list the species. Two reviewers
suggested that surveys done too late to be included into the proposed
rule, be included in the final rule discussion. We have included all
known survey data into this rule and encourage further surveys be done
to better understand the current range of this rare species. Three of
the peer reviewers provided additional information on the species life
history, genetics, and distribution and one of the four reviewers
provided technical corrections on material contained in the sections
titled ``Background'' and ``Summary of Factors Affecting the Species.''
We have incorporated their comments, where appropriate, into this final
determination.
Summary of Factors Affecting the Species
Section 3 of the Act and regulations (50 CFR part 424) promulgated
to implement the listing provisions of the Act set forth the procedures
for adding species to the Federal List of Endangered and Threatened
Wildlife. After a thorough review and consideration of all information
available, we determine that the Buena Vista Lake shrew should be
classified as an endangered species. We may determine a species to be
endangered or threatened due to one or more of the five factors
described in section 4(a)(1) of the Act. These factors, and their
application to the Buena Vista Lake shrew (Sorex ornatus relictus), are
as follows:
A. The Present or Threatened Destruction, Modification, or Curtailment
of Its Habitat or Range
The amount of suitable habitat for the Buena Vista Lake shrew has
been significantly reduced over time due to the systematic drainage of
land and shallow lakes for the purpose of agricultural crop production.
As a result, over 95 percent of the riparian vegetation and associated
marsh habitat of the southern San Joaquin Valley has been eliminated
(TNC 1984 in Service 1986; Werschkull et al. 1992). At this time, the
Buena Vista Lake shrew is known from only four locations: the Kern
Preserve, Cole Levee, the Kern Fan recharge area, and the Kern NWR.
Rapid agricultural, urban, and energy developments since the early
1900s have severely reduced and fragmented native habitats throughout
the San Joaquin Valley (Mercer and Morgan 1991). Historically, the
former Tulare, Buena Vista, Goose, and Kern Lakes, along with their
respective overflow marshes, covered 19 percent of the Tulare Basin in
the southern San Joaquin Valley (Werschkull et al. 1992). Around the
turn of the 20th century, the Tulare Basin had 104,890 ha (259,189 ac)
of valley fresh water marsh, 177,005 ha (437,388 ac) of valley mixed-
riparian forests, and 105,333 ha (260,283 ac) of valley sink scrub, for
a total of 387,229 ha (956,860 ac) of potentially suitable Buena Vista
Lake shrew habitat (TNC 1984, cited in Service 1986). By the early
1980s, the combined total had been reduced to 19,019 ha (46,996 ac),
less than 5 percent of the original habitat (TNC 1984, cited in Service
1986; Werschkull et al. 1992). As of 1995, intensive irrigated
agriculture comprised 1,239,961 ha (3,064,000 ac) or about 96 percent
of the total lands within the Tulare Basin.
All of the natural plant communities in the Tulare Basin have been
affected by the transformation of this area to production of food,
fiber, and fuel (Spiegel and Anderson 1992; Griggs et al. 1992). As
more canals were built, and more water was diverted for irrigation of
the floodplains of the major rivers of the southern San Joaquin Valley,
less water was available to keep the riparian forests alive, and less
water reached the lakes. By the early 1930s, the former Tulare, Buena
Vista, Goose, and Kern lakes were virtually dry and open for
cultivation (Griggs et al. 1992).
Water delivery to maintain the Kern Preserve and support the Buena
Vista Lake shrew habitat cannot be assured because the natural water
table has been lowered by past and present agricultural practices on
and around the Kern Preserve. From the first year TNC leased the
property in 1986, until they decided not to renew the lease in 1995,
the landowner supplied water to the Kern Preserve only during years of
high runoff, at times when excess water was available at the end of the
growing season, and after commercial crop needs were met. Without a
dependable water supply of approximately 15 to 20 acre-feet (ac-ft)
required to maintain the Kern Preserve's wetlands, the continued
existence of the Buena Vista Lake shrew at this location is unlikely.
If sufficient water is not provided, the Gator Pond on the Kern
Preserve, and surrounding mesic habitat that supports this population,
could dry out. The lack of a guaranteed water supply was one of the
major reasons TNC determined that the habitat on the Kern Preserve
could not remain viable and led to TNC's refusal to renew the lease and
manage the Kern Preserve (Sabin Phelps, TNC, pers. comm., 1995).
The Kern NWR was established in 1960 on 4,297 ha (10,618 ac) of
land surrounded by thousands of acres of agricultural land, and over
the years has been managed primarily for waterfowl (Service 1986). The
Kern NWR receives some water from the canalized Poso Creek and from
purchases from willing sellers via the Goose Lake canal. The
availability of adequate amounts of water to meet the needs of all Kern
NWR wildlife is not always possible especially in dry years when the
water demands of nearby crops are high and a willing seller of water is
hard to find. Recently, the BOR has considered the water needs of
several National Wildlife Refuges in the San Joaquin Valley and,
through contract agreements with local water agencies, has attempted to
provide the Kern NWR with a more predictable and stable water supply so
that enough water is available to maintain wetland habitat for
waterfowl and other wildlife species, including the Buena Vista Lake
shrew (BOR 2000).
The Kern NWR has approximately 182 ha (450 ac) of riparian habitat
which requires 2.6 to 3.0 ac-ft per acre each month from November until
late May or early June (BOR 2000), or approximately 10,000 ac-ft per
year. In accordance with the Water Acquisition Program for Central
Valley Project Improvement Act (CVPIA) sections 3406(b)(3), (d)(2) and
(g), the BOR will be delivering 8,000 ac-ft to the Kern NWR during
fiscal year 2002 (Service and BOR 2001). However, according to the
draft Biological Assessment and Biological Opinion on Refuge Water
Supply Conveyance Facilities, 9,450 ac-ft are needed for riparian
habitat (BOR 2000). In addition, 1,800 ha (4,450 ac) of other seasonal
wetland habitat that is flooded from fall (October) through July
requires 3.1 to 3.5 ac-ft per acre of water for a total of 15,575 ac-ft
to meet all riparian/wetland water requirements. Therefore, the amount
of water that is expected to be available is not adequate to support
full ecosystem function on the entire area of riparian and wetland
habitat that supports the Buena Vista Lake shrew on the Kern NWR.
Without full deliveries of water to the Kern NWR, the continued
existence of the Buena Vista Lake shrew may not be assured.
[[Page 10107]]
B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
The subspecies has no known commercial or recreational value.
C. Disease or Predation
Although no cases of disease related to Buena Vista Lake shrews
have been documented, the possibility of disease and associated threats
exists. The small population size and restricted distribution increases
their vulnerability to epidemic diseases. Buena Vista Lake shrews, like
most small mammals, are host to numerous internal and external
parasites, such as round worms, mites, ticks, and fleas, that may
infest individuals and local populations in varying degrees with
varying adverse effects (Churchfield 1990; J. Maldonado, pers. comm.,
1998). However, the significance of the threat of disease and parasites
to the Buena Vista Lake shrew is not known.
Most vertebrate carnivores of the Tulare Basin, such as coyotes
(Canis latrans), foxes (Vulpes spp.), long-tailed weasels (Mustela
frenata), raccoons (Procyon lotor), feral cats (Felis cattus), and dogs
(Canis familiaris), as well as certain avian predators such as hawks,
owls, herons, jays, and egrets, are all known predators of small
mammals. While many predators find shrews unpalatable because of the
distasteful secretion and offensive odor from their flank glands and
feces, several of the avian predators, such as barn owls (Tyto alba),
short eared owls (Asio flammeus), long-eared owls (Asio otus), and
great horned owls (Bubo virginianus), have a poor sense of smell and
are known to prey on shrews (Ingles 1965; Aitchison 1987; Marti 1992;
Holt and Leasure 1993; Marks et al. 1994; Houston et al. 1998), and
probably Buena Vista Lake shrews (J. Maldonado, pers. comm., 1998). The
overall impact that predation may have on the number of individuals and
densities of Buena Vista Lake shrews remains unknown.
D. The Inadequacy of Existing Regulatory Mechanisms
The primary cause of decline of the Buena Vista Lake shrew is the
loss and fragmentation of habitat due to human activities. Federal,
State, and local laws have not been adequate in preventing destruction
of the limited Buena Vista Lake shrew habitat.
Under section 404 of the Clean Water Act (CWA) (33 U.S.C. 1344 et
seq.), the U.S. Army Corps of Engineers (Corps) regulates the discharge
of fill material into waters of the United States, including wetlands.
Section 404 regulations require applicants to obtain a permit for
projects that involve the discharge of fill material into waters of the
United States, including wetlands. However, many farming activities do
not require a permit due to their exemption under the CWA (53 FR 20764;
R. Wayland III, Environmental Protection Agency (EPA), in litt. 1996).
Projects that are subject to regulation may qualify for authorization
to place fill material into headwaters and isolated waters, including
wetlands, under several nationwide permits. The use of nationwide
permits by an applicant or project proponent is normally authorized
with minimal environmental review by the Corps. No activity that is
likely to jeopardize the continued existence of a threatened or
endangered species, or that is likely to destroy or adversely modify
designated critical habitat of such species, is authorized under any
nationwide permit. An individual permit may be required by the Corps if
a project otherwise qualifying under a nationwide permit would have
greater than minimal adverse environmental impacts.
Recent court cases may further limit the Corps' ability to utilize
the CWA to regulate the fill or discharge of fill or dredged material
into the aquatic environment within the current range of the shrew
(Solid Waste Agency of Northern Cook County v. U.S. Army Corps of
Engineers, 531 U.S. 159 (2001) (SWANCC)). The effect of SWANCC on the
Federal ability to regulate activities on wetlands in the area of the
Buena Vista Lake shrew has not been determined by the Corps, but these
wetlands could be determined to be ``isolated'' and, therefore, not
subject to the CWA because these wetlands do not currently drain to a
navigable water of the United States, or may otherwise be shown to have
little connection to interstate commerce.
In addition, common activities such as ditching within aquatic
habitats in the area may not be subject to the CWA provided such
activities do not deposit more than minimal ``fallback'' into the
aquatic environment. The Corps typically confines its evaluation of
impacts only to those areas under its jurisdiction (i.e., wetlands and
other waters of the United States).
The California Environmental Quality Act (CEQA) (Public Resources
Code Sec. 21000-21177) requires a full disclosure of the potential
environmental impacts of proposed projects. The public agency with
primary authority or jurisdiction over a project is designated as the
lead agency and is responsible for conducting a review of the project
and consulting with the other agencies concerned with the resources
affected by the project. Section 15065 of the CEQA Guidelines, as
amended, requires a finding of significance if a project has the
potential to ``reduce the number or restrict the range of a rare or
endangered plant or animal.'' Once significant effects are identified,
the lead agency has the option of requiring mitigation for effects
through changes in the project or to decide that overriding
considerations make mitigation infeasible (CEQA Sec. 21002). In the
latter case, projects may be approved that cause significant
environmental damage, such as destruction of listed endangered species
and/or their habitat. Protection of listed species through CEQA is,
therefore, dependent upon the discretion of the agency involved.
However, the Buena Vista Lake shrew is not listed as an endangered,
threatened, or candidate species under the California Endangered
Species Act.
E. Other Natural or Manmade Factors Affecting Its Continued Existence
If shrew population ranges overlap or come in contact through
expansion, then hybridization may occur in closely related species and
certain subspecies (Rudd 1955a). Over time, a population of a
subspecies could become genetically indistinguishable from a larger
population of an introgressing subspecies such that the true genotype
of the lesser subspecies no longer exists (Lande 1999). Apparent
hybrids have been recorded between two subspecies of ornate shrew, the
California ornate shrew (Sorex. ornatus californicus) and the Suisun
Marsh ornate shrew (S. o. sinuosus), found on the northern side of the
San Pablo and Suisun bays in Solano County, California (Rudd 1955a;
Hays 1990). Although there is no documented evidence of hybrids, the
possibility exists for introgression between the upland Southern
California ornate shrew with the lowland Buena Vista Lake shrew.
Unidentified subspecies of the ornate shrew have been captured on
recently retired farmland south of Mendota in Fresno County (Williams
and Harpster 2001; ESRP and BOR 2001).
Selenium toxicity represents a serious threat to the continued
existence and recovery of the Buena Vista Lake shrew, not only at the
two known locations at the Kern Preserve and the Kern NWR, but any
potential locations throughout the Tulare Basin. The soils on the
western side of the San Joaquin Valley have naturally elevated selenium
concentrations. Due to extensive agricultural irrigation, selenium has
[[Page 10108]]
been leached from the soils and concentrated in the shallow groundwater
along the western side of the San Joaquin Valley. Where this shallow
groundwater reaches the surface or subsurface, selenium can accumulate
in biota (flora and fauna) and result in adverse effects to growth,
reproduction, and survival. Elevated concentrations of selenium have
caused major wildlife mortalities in places like Kesterson (Moore et
al. 1989). The EPA's water quality criterion for the protection of
aquatic species is currently 5 micrograms/liter (g/L) but is
being reevaluated by that agency (65 FR 31681). The selenium standard
to protect wetlands in the grassland area of the San Joaquin Valley is
2 /L. Some of the highest selenium levels in the western
United States (greater than 1,100 g/L) have been measured from
groundwater within the southern San Joaquin Valley, and greater than
200 g/L have been measured in drainwater evaporation ponds
servicing the agricultural lands immediately surrounding the only known
populations of Buena Vista Lake shrews in the Tulare Basin (California
Regional Water Quality Control Board (RWQCB) 1996; DWR 1997; Seiler et
al. 1999).
In addition, the increased supply of imported water and little or
no exported drainwater has resulted in the raising of the selenium-
contaminated groundwater table on the western side of the San Joaquin
Valley and large portions of the Tulare Basin (DWR 1997). Water table
levels have been measured at 1.5 to 3 m (5 to 10 ft) beneath the Kern
Preserve and Kern NWR, and have moved steadily upwards since 1988 (DWR
1997). Between 1984 and 1989, the selenium concentration in shallow
groundwater was measured from wells throughout the Tulare Basin and
ranged from less than 5 g/L to greater than 200 g/L.
The groundwater beneath the Kern NWR ranged between 5 and 50
g/L selenium and between 50 and 200 g/L under the
Kern Preserve, both well above water quality criteria determined by
EPA. Thus, careful surface and groundwater management in these areas is
critical to avoid selenium bioaccumulation in fish and wildlife.
As selenium and other dissolved salts move upward with the shallow
water table, the surface vegetation can take up selenium with the water
via root absorption. The selenium and salts can also reach the surface
via a ``wicking'' action through the soil or the groundwater. The
selenium can then enter the food chain of the Buena Vista Lake shrew by
becoming concentrated in insects that forage on the vegetation or
reside in soils that concentrate these salts (Saiki and Lowe 1987;
Moore et al. 1989). Subsurface drainwater discharged to evaporation
ponds or recirculated in reuse and treatment systems can also allow
this concentrated selenium to accumulate in biota. Elevated
concentrations of selenium in insects have been measured in many
potential Buena Vista Lake shrew prey species such as brine flies
(Ephydridae), damselflies (Zygoptera), midges (Chironomidae), and other
insects collected at 22 agricultural drainage evaporation ponds
throughout the Tulare Basin, including ponds a few miles west of the
Kern Preserve and along the northern border of the Kern NWR (Moore et
al. 1989). In 1989, concentrations of selenium in 96 insects from 7
representative ponds in the Tulare Basin ranged from 0.71 to 303.7
g/gram (g) with a mean of 19.67 g/g (dry weight).
These potential dietary levels of selenium are over six times the level
that causes chronic deleterious symptoms in rodents and over 14 times
what is considered toxic (see toxicity discussion below).
Current data on the selenium concentrations in potential insect
prey from the same seven ponds mentioned above are not available,
however, it has been established that tissue concentrations of selenium
in field-collected aquatic invertebrates are strongly related to
waterborne concentrations of selenium (Birkner 1978; Wilber 1980;
Lillebo et al. 1988). Comparative selenium water concentrations were
measured in 1989 and again in 1996 for these same seven ponds (RWQCB
1996). The mean selenium concentrations in 1996 were within the range
of the mean 1989 selenium concentrations in all seven ponds. Therefore,
the potential exposure and availability of insects with toxic selenium
concentrations remains a threat to the Buena Vista Lake shrew in ponds
with similar selenium concentrations.
No cases of widespread selenium poisoning (selenosis) among wild
mammals in nature has been documented (Skorupa 1998). However, from the
results of intensive research on domestic livestock, researchers
discovered that consumption of seleniferous grass or hay containing
more than 5 g/g selenium was the most common cause of chronic
selenosis, a potentially fatal disease (O'Toole and Raisbeck 1998;
Seiler et al. 1999). From comparative studies on the pathology and
toxicology of selenium poisoning in small mammals, researchers
determined that high levels of selenium in the diet can cause
deleterious effects to the hair, nails, liver, blood, heart, nervous
system, and reproduction (O'Toole and Raisbeck 1998). The lowest
dietary threshold for toxicity in small mammals was 1.4 g/g
(dry weight) and was associated with sublethal effects from lifetime
exposure in rats (Eisler 1985). Longevity was reduced at 3 g/g
in the lifetime diet. Olson (1986) reports a minimum dietary exposure
associated with reproductive selenosis in rats of 3 g/g.
Female rats fed a selenized diet either died of liver failure or were
infertile (O'Toole and Raisbeck 1998). Anemia from hemolysis (rupture
of red blood cells) is consistently produced in rats fed more than 15
g/g dietary selenium (Franke 1934; Halverson et al. 1970).
A 666-ha (1,646-ac) experimental site south of Mendota in Fresno
County has been monitored to assess the changes over time of
restoration efforts, groundwater levels, and selenium concentrations in
terrestrial invertebrates and small mammals once irrigation was stopped
on the site (ESRP and BOR 2001). In 1999 and 2000, the range of
selenium concentration in 34 beetles, crickets, isopods, and spiders
ranged from 0.3 g/g to 5.6 g/g (dry weight). These
invertebrates were found to be bioaccumulating selenium at higher
levels on lands actively cultivated than on lands where cultivation
(and irrigation) had ceased or natural areas where groundwater was much
deeper. The selenium concentrations from the livers and whole bodies of
13 ornate shrews (subspecies unknown) captured on uncultivated lands at
the site ranged from 2.0 to 7.8 g/g (dry weight) for livers
and 2.0 to 4.8 g/g for whole body concentrations. These values
are within or slightly above the range of background levels of 1 to 10
g/g for livers and 1 to 4 g/g for whole body selenium
concentrations of small mammals associated with aquatic habitats
(Skorupa 1998); however, they are unlikely to be toxic. Researchers
found higher levels of selenium in the shrews than the mice at the site
and had expected this finding due to the shrews' insectivorous foraging
habits and higher metabolic rates requiring greater food intake per
unit of body mass (ESRP and BOR 2001).
Elevated concentrations of selenium caused major wildlife
mortalities at Kesterson where selenium bioaccumulated in virtually
every biotic compartment in the ecosystem (Moore et al. 1989).
Consistently, ornate shrews have been the small mammal experiencing the
greatest exposures to selenium at Kesterson. Ornate shrews captured
around Kesterson in 1984 showed selenium concentrations 3 to 25
[[Page 10109]]
times greater than those found for any other small mammal at the same
site (Clark 1987). During periodic monitoring from 1984 to 1998, mean
annual whole body concentrations of selenium in shrews ranged from 7.5
g/g to 38 g/g (Dale Pierce, Service, in litt. 2000).
The cumulative trapping results for shrews at Kesterson reveal that the
same trapping effort that would have resulted in 100 shrew captures in
1989, would have resulted in only eight shrew captures in 1999. In
comparison, while the trapping rates for the highly selenium-exposed
insectivorous shrews at Kesterson have crashed since 1989, the trapping
rates for the much lesser exposed herbivorous (plant eating) deer mice
have remained stable (D. Pierce, in litt. 2000). Whether selenium is
the direct cause of the population declines of shrews at Kesterson is
complicated by habitat change (filling of low areas) and climate
changes (drought in early 1990s), but selenium bioaccumulation to
harmful levels by shrews is clearly demonstrated at the site.
An additional potential source of selenium exposure to Buena Vista
Lake shrews in the Tulare Basin is from both liquid and solid manure
being produced by concentrated animal feeding operations (dairies, beef
cattle, swine, and poultry operations). The U.S. Food and Drug
Administration (FDA) allows the addition of up to 0.3 g/g of
selenium as a supplementation in livestock feed contrary to their own
analysis of the potential effects on the environment (58 FR 47961). It
was noted that selenium concentrations in a few sampled dairy cow
manure pits had been documented at levels of 63 to 88 g/L (58
FR 47961). By comparison, EPA's current selenium water quality
criterion for the protection of aquatic life is 5 g/L, and 2
g/L is recommended for the protection of wetland habitats.
Thus, direct contamination of fish and wildlife habitats is clearly a
potential hazard. Of equal or greater concern is the issue of selenium
loading into the environment via land applications of manure. As FDA
stated (58 FR 47968), ``Agricultural soils are highly manipulated
oxidized systems that tend to favor formation of selenite and selenate
and stimulate microbial activities.'' Much previous research has
revealed that selenium in the form of selenate is highly mobile in the
environment and is easily transported to aquatic ecosystems where it
can rapidly become bioaccumulated to toxic levels (e.g., papers in
Frankenberger and Engberg 1998). Thus, Buena Vista Lake shrews and
their prey base could be exposed to potentially toxic levels of
selenium from the on-farm and off-farm application of manure around the
aquatic and moist habitats that support them. Accidental discharges
from waste storage ponds during storm events could also release
additional selenium into the environment.
The potential of additional exposure to toxic levels of selenium
from beef cattle, dairy, swine, and poultry waste production appears to
be increasing. Using dairy as an example, the Council for Agricultural
Science and Technology (CAST) in 1994 published some vital statistics
regarding selenium dynamics of lactating Holstein cows. For a herd
receiving feed supplemented with 0.3 g/g selenium, each cow
excreted an average of 6.4 milligrams selenium (in urine and manure)
per day (CAST 1994:13). That works out to the equivalent of 1.668 g
selenium/year (yr) per animal unit (AU). This comes from a standard
assumption that a lactating Holstein cow in a producing dairy
operation, within the same geographic region that the Buena Vista Lake
shrew occurs in, equals 1.4 AU and there are 365 days in a year. Thus,
100,000 AU would result in about 166,800 g of selenium being introduced
into the environment each year. Now consider the number of dairy AU in
the Tulare Basin of California. In 2000, Kern County had 65,000 milk
cows; Fresno County, over 79,000 milk cows; Kings County had over
120,000 milk cows; and Tulare County had nearly 358,000 milk cows
(California Department of Food and Agriculture 2001). Combined, the
four counties had over 622,000 milk cows, and at 1.4 AU per milk cow,
this equals 870,800 AU. That translates to 1,452,494 g of selenium
being introduced into the environment. These dairies are large, with
the average size in Kern County of over 1,600 head and 1,100 head in
Tulare County. Also, they are not evenly spread across the landscape
and are often concentrated around urban centers, processing facilities,
or sources of water. The manure is also not evenly distributed across
the landscape and is most often used to fertilize the agricultural
lands on or adjacent to the dairies. Finally, this does not consider
beef cattle, swine, and poultry operations that can also use selenium
supplements.
The FDA (58 FR 47961) constructed a model to evaluate the addition
of 3.9 g of selenium per hectare via application of chicken manure and
calculated that such a scenario would lead to surface runoff from the
amended fields that contained 7.8 g/L of selenium, or 1.56
times EPA's aquatic life criterion. FDA's model did not consider the
cumulative effects of repeated annual additions of selenium to the
environment, but only looked at the scenario of a one-time land
application of manure. This model applied to the Tulare Basin would
mean that, to apply the 1.4 million g of selenium (from 870,800 AU) at
the same rate used in the FDA model, over 373,121 ha (922,000 ac) of
land would be required to safely land-apply dairy manure alone. The
Central Valley Regional Water Quality Control Board (RWQCB) recommends
that each dairy determine the manure application rates to their land
based on nitrogen loading, but offers a basic rule of 5 cows per acre
of double-cropped land as a ``reasonable rate'' for manure application
(RWQCB 2001). Using 870,800 AU, this would translate to 70,480 ha
(174,160 ac) needed in the Tulare Basin. Therefore, application of
manure in accordance with the RWQCB's basic rule for nutrient
management would likely result in selenium concentrations far in excess
of safe levels in runoff. Remaining shrew habitat is at the lowest
elevation within the surrounding agricultural region. Thus, it is the
area to which runoff will tend to flow unless carefully and actively
managed to avoid flooding and human error overflows that would affect
Buena Vista Lake shrew habitat.
Additional perspective can be gained from a study of Stewart Lake,
Utah (Stephens et al. 1992), where it was found that annual loading of
only 252 g (8.9 ounces) of selenium (to the 101 surface-hectare (250
surface-acre) lake) was sufficient to cause selenium bioaccumulation in
waterfowl eggs of over 20 g/g (a toxic dose that caused embryo
deformities). Thus, with an addition of only 2.5 g of selenium per
surface hectare of the lake, severe selenium poisoning of wildlife
occurred.
The number of dairy cows and new dairy operations that have been
proposed or approved for Kern County has suddenly increased in and
around the last remaining habitats of the Buena Vista Lake shrew. Six
dairies have approved conditional use permits, and another nine dairies
are pending approval, which could increase the number of dairies in
Kern County from 37 to 52, and the number of milk cows from 60,000 to
112,500 (Bedell 2000). If these animals are fed supplements that have
selenium concentrations of 0.3 g/g and each cow excretes 6.4
milligrams per day (CAST 1994), or 1.668 g/yr/AU, and if each lactating
dairy cow equals 1.4 AU, then 262,710 g (or 263 billion g) of
selenium could potentially enter the Kern County environment each year.
This only includes the dairy farms in
[[Page 10110]]
Kern County and not the additional dairy herds in Kings and Tulare
counties or other animal feeding operations.
Buena Vista Lake shrews are exposed to the wide-scale use of
pesticides throughout their range, because they currently exist on
small remnant patches of natural habitat in and around the margins of
an otherwise agriculturally dominated landscape. Buena Vista Lake
shrews could be directly exposed to lethal and sublethal concentrations
of pesticides from drift or direct spraying of crops, canals and ditch
banks, wetland or riparian edges, and roadsides where shrews might
exist. Reduced reproduction in Buena Vista Lake shrews could be
directly caused by pesticides through grooming, and secondarily from
feeding on contaminated insects (Sheffield and Lochmiller 2001). Buena
Vista Lake shrews could also die from starvation by the loss of their
prey base (Ma and Talmage 2001; Sheffield and Lochmiller 2001).
Exposure to organophosphate and carbamate insecticides can inhibit
brain acetylcholinesterase activity leading to alterations in behavior
and motor activity. Laboratory experiments have shown that behavioral
activities such as rearing, exploring for food, and sniffing can be
depressed for up to 6 hours in the common shrew (Sorex araneus) from
environmental and dietary exposure to sublethal doses of a widely used
insecticide called dimethoate (Dell'Omo et al. 1999). In their natural
habitat, depression in such behavioral and motor activities could make
the shrews more vulnerable to predation, and starvation. In addition,
shrews may feed heavily on intoxicated arthropods after application of
insecticides, and, therefore, ingest higher concentrations of
pesticides than would normally be available (Stehn et al. 1976;
Schauber et al. 1997; Sheffield and Lochmiller 2001). Fresno, Kern, and
Tulare counties are the three highest users of pesticides in California
with 16,773,126 kilograms (kg) (36,978,444 pounds (lb)); 10,985,201 kg
(24,218,242 lb); and 7,562,064 kg (16,671,512 lb) of pesticide active
ingredients used respectively in 1999 (Pesticide Board 2000).
One of the main reasons the Kern NWR was established was to provide
waterfowl wintering habitat in the San Joaquin Valley (Service 1986). A
waterfowl hunting program is provided in cooperation with the CDFG. In
order to attract large numbers of waterfowl, large areas of the Refuge,
including Unit 4A where Buena Vista Lake shrews were found, are flooded
each year. Starting in August and September, water is released, and
these areas remain flooded until March or April. This allows Buena
Vista Lake shrews to exist only on narrow patches of unsubmerged
habitat along the levee roads and trails that provide access to
thousands of hunters, their dogs, and vehicles yearly (Service 1986).
Hunters are also allowed to remain overnight, and their presence could
cause disruptions in the behavior of the shrews. Due to their small
size and high metabolic rates, shrews have short starvation times, and
any disturbance, even for a short period, could prove fatal (Hanski
1994). As mentioned, shrews need to capture and consume between 24 and
48 insects over a 24-hour period, even during the colder winter months
when thermoregulatory costs account for a major part of the energy
expenses (Genound 1988).
The only known populations of Buena Vista Lake shrews are also
vulnerable to environmental risks associated with small, restricted
populations. Impacts to populations that can lead to extinction include
the loss or alteration of essential elements for breeding, feeding, and
sheltering; the introduction of limiting factors into the environment
such as poison or predators; and catastrophic random changes or
environmental perturbations, such as floods, droughts, or disease
(Gilpin and Soule 1986). Many extinctions are the result of a severe
reduction of population size by some deterministic event such as
lowered birth rates due to exposure to certain toxins such as selenium,
followed by a random natural event such as a crash in insect
populations from an extended drought which causes the extirpation of
the species. The smaller a population is, the greater its vulnerability
to such perturbations (Terbough and Winter 1980; Gilpin and Soule 1986;
Shaffer 1987). The elements of risk that are amplified in very small
populations include: (1) The impact of high death rates or low birth
rates; (2) the effects of genetic drift (random fluctuations in gene
frequencies) and inbreeding; and (3) deterioration in environmental
quality (Gilpin and Soule 1986; Lande 1999). When the number of
individuals in a population of a species or subspecies is sufficiently
low, the effects of inbreeding may result in the expression of
deleterious genes in the population (Gilpin 1987). Deleterious genes
reduce individual fitness in various ways, most typically by decreasing
survivorship of young. Genetic drift in small populations decreases
genetic variation due to random changes in gene frequency from one
generation to the next. This reduction of variability within a
population limits the ability of that population to adapt to
environmental changes (Lande 1999).
One scenario where loss of habitat may lead to extinction is when a
species is a local endemic (because of its isolation and restricted
range) (Gilpin and Soule 1986). The Buena Vista Lake shrew is a limited
local endemic subspecies (Williams and Kilburn 1992) that has never
been found to be locally abundant and lives in very restricted areas of
marshy wetland habitat (Bradford 1992). Because there are less than 30
known individuals in four populations (on approximately 575 ac) the
Buena Vista Lake shrew is extremely vulnerable to natural or human-
caused environmental impacts.
Conclusion
In developing this rule, we have carefully assessed the best
scientific and commercial information available regarding the past,
present, and future threats facing this subspecies. The Buena Vista
Lake shrew is imperiled primarily by agricultural activities,
modifications and potential impacts to local hydrology, uncertainty of
water availability and delivery to support riparian and marsh habitat,
possible toxic effects from selenium poisoning, and by random,
naturally occurring events. Only four isolated populations are known to
exist. This subspecies is in danger of extinction ``throughout all or a
significant portion of its range'' (section 3(6) of the Act) and,
because of the high potential that these threats could result in the
extinction of the Buena Vista Lake shrew, the preferred action is to
list the subspecies as endangered.
Critical Habitat
Critical habitat is defined in section 3 of the Act as: (i) The
specific areas within the geographical area occupied by a species, at
the time it is listed in accordance with the Act, on which are found
those physical or biological features (I) essential to the conservation
of the species, and (II) that may require special management
consideration or protection; and (III) specific areas outside the
geographical area occupied by a species at the time it is listed in
accordance with the provisions of section 4 of the Act, upon a
determination that such areas are essential for the conservation of the
species. ``Conservation'' means the use of all methods and procedures
needed to bring the species to the point at which listing under the Act
is no longer necessary.
[[Page 10111]]
Section 4(a)(3) of the Act, as amended, and implementing
regulations (50 CFR 424.12) require that, to the maximum extent prudent
and determinable, we designate critical habitat at the time the species
is determined to be endangered or threatened. Our regulations (50 CFR
424.12(a)(1) state that the designation of critical habitat is not
prudent when one or both of the following situations exist--(1) the
species is threatened by taking or other human activity, and
identification of critical habitat can be expected to increase the
degree of threat to the species, or (2) such designation of critical
habitat would not be beneficial to the species.
The primary regulatory effect of critical habitat is the
requirement in section 7 of the Act that Federal agencies refrain from
taking any action that destroys or adversely modifies critical habitat.
While a critical habitat designation for habitat currently occupied by
this subspecies would not be likely to change the section 7
consultation outcome because an action that destroys or adversely
modifies such critical habitat would also be likely to result in
jeopardy to the subspecies, there may be instances where section 7
consultation would be triggered only if critical habitat is designated.
Examples could include unoccupied habitat or occupied habitat that may
become unoccupied in the future. Designating critical habitat may also
produce some educational or informational benefits. Therefore, we find
that designation of critical habitat is prudent for the Buena Vista
Lake shrew.
However, our budget for listing activities is currently
insufficient to allow us to immediately complete all the listing
actions required by the Act. Listing the Buena Vista Lake shrew without
designation of critical habitat will allow us to concentrate our
limited resources on other listing actions that must be addressed,
while allowing us to invoke protections needed for the conservation of
this subspecies without further delay. This is consistent with section
4(b)(6)(C)(i) of the Act, which states that final listing decisions may
be issued without critical habitat designations when it is essential
that such determinations be promptly published. We will prepare a
critical habitat designation in the future at such time when our
available resources and priorities allow.
Available Conservation Measures
Conservation measures provided to species listed as endangered or
threatened under the Act include recognition, recovery actions,
requirements for protection, and prohibitions against certain
activities. Recognition through listing results in public awareness and
conservation actions by Federal, State, and local agencies, private
organizations, and individuals. The Act provides for possible land
acquisition and cooperation with the States and requires that recovery
actions be carried out for all listed species. The protection required
of Federal agencies and the prohibitions against taking and harm are
discussed, in part, below.
Section 7(a) of the Act, as amended, requires Federal agencies to
evaluate their actions with respect to any species that is proposed or
listed as endangered or threatened, and with respect to its critical
habitat, if any is being designated. Regulations implementing this
interagency cooperation provision of the Act are codified at 50 CFR
part 402. Section 7(a)(4) of the Act requires Federal agencies to
confer with us on any action that is likely to jeopardize the continued
existence of a species proposed for listing or result in destruction or
adverse modification of proposed critical habitat. If a species is
listed subsequently, section 7(a)(2) of the Act requires Federal
agencies to ensure that activities they authorize, fund, or carry out
are not likely to jeopardize the continued existence of the species or
destroy or adversely modify its critical habitat. If a Federal action
may affect a listed species or its critical habitat, the responsible
Federal agency must enter into formal consultation with us.
Federal activities that could occur and impact the Buena Vista Lake
shrew include, but are not limited to, stream or river alterations,
applicable EPA permits concerning concentrated animal feeding
operations, water withdrawal projects, agricultural subsidy and
assistance programs, road and bridge construction, Federal loan
programs, Federal water deliveries, pesticide registration and use,
levee and canal construction or maintenance activities, and fire
management activities on Federal land.
We developed a Recovery Plan for Upland Species of the San Joaquin
Valley, California (Recovery Plan), on September 30, 1998 (Service
1998). This Recovery Plan includes a recovery strategy for the Buena
Vista Lake shrew which includes the general criteria for long-term
conservation. The recovery criteria for the subspecies are defined
under the following headings: Secure and protect three or more disjunct
occupied sites collectively with at least 2,000 ha (4,940 ac) of
occupied habitat; have a management plan approved and implemented for
recovery areas that include survival of the subspecies as an objective;
and monitor the specified recovery areas to demonstrate the continued
presence at known occupied sites. In spite of published recovery
objectives, habitat of the Buena Vista Lake shrew remains unprotected
and the subspecies is vulnerable to numerous threats as discussed.
Although the Recovery Plan delineated reasonable actions that were
believed to be required and adequate to recover and protect the species
at the time they were written, they are subject to modification as
dictated by new findings (Service 1998). The information contained in
the proposed rule (65 FR 35033) and this final rule (see Summary of
Factors Affecting the Species) may modify the criteria expected to be
necessary from those outlined in the Recovery Plan for the long-term
conservation of the Buena Vista Lake shrew.
The Act and its implementing regulations set forth a series of
general prohibitions and exceptions that apply to all endangered
wildlife. These prohibitions, in part, make it illegal for any person
subject to the jurisdiction of the United States to take, (includes
harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or to
attempt any of these), import or export, ship in interstate commerce in
the course of commercial activity, or sell or offer for sale in
interstate or foreign commerce any endangered wildlife species. It is
also illegal to possess, sell, deliver, carry, transport, or ship any
such wildlife that has been taken illegally. Certain exceptions apply
to our agents and State conservation agencies.
Permits may be issued to carry out otherwise prohibited activities
involving endangered wildlife under certain circumstances. Regulations
governing permits are codified at 50 CFR 17.22 and 17.23. For
endangered species, such permits are available for scientific purposes,
to enhance the propagation or survival of the species, and for
incidental take in connection with otherwise lawful activities.
Our policy, published in the Federal Register on July 1, 1994 (59
FR 34272), is to identify, to the maximum extent practicable,
activities that likely would or would not be contrary to section 9 of
the Act. The intent of this policy is to increase public awareness of
the effect of this listing on proposed and ongoing activities within
the subspecies' range.
With respect to the Buena Vista Lake shrew, based on the best
available information, the following actions would not be likely to
result in a violation of section 9, provided these
[[Page 10112]]
activities are carried out in accordance with existing regulations and
permit requirements:
(1) Possession of legally acquired Buena Vista Lake shrews; and
(2) Federally approved projects that involve activities such as
discharge of fill material, draining, flooding, ditching, tilling, pond
construction, wetland or riparian habitat enhancement or construction,
stream channelization or diversion, canal or pipeline construction,
alteration of surface or ground water into or out of riparian areas
(i.e., due to roads, impoundments, discharge pipes, storm water
detention basins, etc.), wildlife habitat restoration, or other such
activity when it is conducted in accordance with any reasonable and
prudent measures given by us in accordance with section 7 of the Act,
or in accordance with a section 10(a)(1)(B) permit.
With respect to the Buena Vista Lake shrew, activities that could
potentially result in a violation of section 9 of the Act include, but
are not limited to, the following:
(1) Unauthorized killing, injuring, harassing, collecting,
trapping, handling, or holding in captivity of Buena Vista Lake shrews;
(2) Unauthorized destruction or alteration of the Buena Vista Lake
shrew's habitat through discharge of fill material, draining, flooding,
ditching, tilling, pond construction, wetland or riparian habitat
enhancement or construction, stream channelization or diversion, canal
or pipeline construction, alteration of surface or ground water into or
out of riparian areas (i.e., due to roads, impoundments, discharge
pipes, storm water detention basins etc.);
(3) Burning, cutting, or mowing of riparian vegetation, repair and
maintenance of water and sewer lines, levee or road maintenance, and
the spraying of insecticides or herbicides on or in riparian or other
supportive habitat if not in accordance with reasonable and prudent
measures provided by us in accordance with section 7 of the Act or with
conditions of a section 10(a)(1)(A) permit;
(4) Discharge or dumping of toxic chemicals, silt, or other
pollutants (sewage, oil, and gasoline) into land supporting the
subspecies. This includes any application of terrestrial or aquatic
pesticide that results in mortality or injury of Buena Vista Lake
shrews, regardless if the pesticide was applied in accordance with the
labeling instructions. This includes drift from aerial applications and
runoff from surface applications; and
(5) Possessing, selling, transporting, or shipping illegally taken
Buena Vista Lake shrews.
Questions regarding whether specific activities risk violating
section 9 of the Act should be directed to our Sacramento Fish and
Wildlife Office (see ADDRESSES section). Requests for copies of the
regulations on listed plants and animals, and general inquiries
regarding prohibitions and permits may be addressed to the U.S. Fish
and Wildlife Service, Ecological Services, Endangered Species Permits,
911 N.E. 11th Avenue, Portland, OR, 97232-4181 (telephone 503/231-2063;
facsimile 503/231-6243).
National Environmental Policy Act
We have determined that Environmental Assessments or Environmental
Impact Statements, as defined under the authority of the National
Environmental Policy Act of 1969, need not be prepared in connection
with regulations adopted pursuant to sections 4(a) of the Act. We
published a notice outlining our reasons for this determination in the
Federal Register on October 25, 1983 (48 FR 49244).
Paperwork Reduction Act
This rule does not contain any new collections of information other
than those already approved under the Paperwork Reduction Act, 44
U.S.C. 3501 et seq., and assigned Office of Management and Budget
clearance number 1018-0094. An agency may not conduct or sponsor, and a
person is not required to respond to, a collection of information,
unless it displays a currently valid control number. For additional
information concerning permits and associated requirements for
endangered wildlife species, see 50 CFR 17.22.
References Cited
A complete list of all references cited in this rulemaking is
available upon request from the Sacramento Fish and Wildlife Office
(see ADDRESSES section).
Author
The primary authors of this final rule are the staff of the
Sacramento Fish and Wildlife Office (see ADDRESSES section) (telephone
916/414-6600).
List of Subjects in 50 CFR Part 17
Endangered and threatened species, Exports, Imports, Reporting and
recordkeeping requirements, Transportation.
Regulation Promulgation
Accordingly, we amend part 17, subchapter B of chapter I, title 50
of the Code of Federal Regulations, as follows:
PART 17--[AMENDED]
1. The authority citation for part 17 continues to read as follows:
Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C.
4201-4245; Pub. L. 99-625, 100 Stat. 3500, unless otherwise noted.
2. Amend section 17.11(h) by adding the following, in alphabetical
order under Mammals, to the List of Endangered and Threatened Wildlife:
Sec. 17.11 Endangered and threatened wildlife.
* * * * *
(h) * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
Species Vertebrate
------------------------------------------------------- population where Critical Special
Historic range endangered or Status When listed habitat rules
Common name Scientific name threatened
--------------------------------------------------------------------------------------------------------------------------------------------------------
MAMMALS
* * * * * * *
Shrew, Buena Vista Lake.......... Sorex ornatus U.S.A. (CA)........ Entire............. E NA NA
relictus.
* * * * * * *
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[[Page 10113]]
Dated: February 28, 2002.
Steve Williams,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 02-5274 Filed 3-5-02; 8:45 am]
BILLING CODE 4310-55-P