The U.S. Fish and Wildlife Service is listing the distinct population segment of the wolverine in the contiguous U.S. as a threatened species under the Endangered Species Act. The Service is also issuing an interim rule under section 4(d) of the ESA to exempt the take of wolverines related to research activities, incidental trapping mortality, and forest management activities reducing the risk or severity of wildfire in the contiguous U.S. 

A distinct population segment is a vertebrate population or group of populations that are distinct from other populations of the species and significant to the entire species. Under the ESA, species, subspecies, or distinct population segments of vertebrate species are eligible for listing. NOAA Fisheries and the U.S. Fish and Wildlife Service have a joint policy defining the criteria for identifying a population as a DPS (61 FR 4722; February 7, 1996). 

The Service initially proposed a 4(d) rule for the wolverine in 2013 in association with the Service’s proposal to classify the wolverine as a threatened species (78 FR 7864). The Service took comments on the 2013 proposed 4(d) rule and has considered the comments received regarding the proposed 4(d) rule in developing this interim rule.

This 4(d) rule was prepared with notice and comment rulemaking, and the Service could have issued it as a final rule, and not as an interim rule with an additional comment period. However, the Service elected to issue this as an interim 4(d) rule and take public comments to assure a robust opportunity for the public to consider the prohibitions and exceptions prescribed while providing protections for the threatened wolverine and complying with our court-ordered deadline to finalize the listing determination.

For detailed information on previous federal actions, please visit https://www.federalregister.gov/documents/2016/10/18/2016-24929/endangered-and-threatened-wildlife-and-plants-proposed-rule-for-the-north-american-wolverine.

The U.S. Fish and Wildlife Service proposed to list the wolverine in the contiguous U.S. as a threatened species in 2013 (78 FR 7864; February 4, 2013). In 2020, after reevaluating the wolverine’s status, the Service determined listing the wolverine was not warranted (85 FR 64618; October 13, 2020). 

The 2020 not-warranted determination was withdrawn and litigated. In 2022, the District Court of Montana vacated that decision, meaning the wolverine in the contiguous U.S. was again considered a species proposed for listing under the ESA (Center for Biological Diversity et al. and Wild Earth Guardians et al. v. Haaland, et al., No. 9:20-cv-00181-DWM (D. Mont. May 26, 2022). 

A species status assessment is a biological risk assessment that helps decision-makers evaluate the best available scientific information to recommend and inform policy decisions under the ESA. Since 2018, a significant amount of new scientific information on the wolverine and its status has become available. Therefore, it was necessary to reevaluate our 2018 SSA and update our risk assessment with this new information. 

There were six primary differences between the 2018 and 2023 SSAs. These included connectivity with Canada, genetic diversity and adaptative capacity, ecological requirements, dispersal/human disturbance, winter recreation, and trapping in southern Canada. 

Connectivity with Canada - Connectivity with Canada is essential to the long-term viability of wolverines in the lower 48 states. However, new research shows the wolverine population in the southern Canadian Rockies in Canada, an important area for wolverine connectivity with the U.S., is declining, and major highways impede female dispersal, which has implications for gene flow. 

Genetic Diversity and Adaptive Capacity - A new comprehensive genetic evaluation spanning the U.S.-Canada border was completed in 2023 and evaluated 887 unique individuals. The research identified issues with low genetic diversity and increasing population fragmentation at the southern extent of the wolverine’s range in western North America. It also found that large highways in southern British Columbia appeared to be restricting the effective dispersal of females from Canada to the U.S.   

Ecological Requirements - New research highlights that wolverines are a snow-adapted species that depend upon areas with persistent spring snow for survival (e.g., caching food) in addition to denning and reproduction in the alpine habitats of the contiguous U.S.  

Dispersal/Human Disturbance - New research points to human development in valley bottoms between core habitats as limiting wolverine dispersal and population connectivity to some extent, especially for females. Human disturbance and food availability were major drivers of wolverine distribution in winter and may change competition dynamics with other carnivores that are advantaged in areas affected by some human disturbance.   

Winter Recreation - New scientific information now shows that backcountry winter recreation is negatively associated with wolverine habitat use. This recreation is likely to increase and become more concentrated in the future as snow-covered areas decline due to climate change climate change
Climate change includes both global warming driven by human-induced emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale.

Learn more about climate change . 

Trapping in Southern Canada - Regulated trapping for wolverines in southern Canada may have negatively impacted wolverine populations more than previously thought. Unsustainable trapping levels in southern Canada appear to have depressed the wolverine population in a portion of southern British Columbia and Alberta. Although the trapping of wolverines was subsequently closed along the U.S.-Canada border in British Columbia, the legacy effects of this population decline could limit the dispersal of individuals into the contiguous U.S. The dispersal of wolverines from southern Canada is vital to the genetic and demographic health of the U.S. population.

The analysis included various studies concerning the effects of backcountry recreation in wolverine habitat. The studies looked at various types of backcountry recreation including skiing, snowboarding, snowshoeing, and snowmobile use. The studies found that wolverines avoided high-quality habitats within their home ranges where these activities were occurring. The Service is not concerned about the effects of winter recreation in established and developed areas such as ski resorts at this time. 

The purpose of the ESA is to provide a means to conserve the ecosystems upon which endangered and threatened species depend and provide a program for the conservation of such species. The ESA directs all federal agencies to participate in conserving these species. Specifically, section 7(a)(1) of the ESA charges federal agencies to aid in the conservation of listed species, and section 7(a)(2) requires the agencies to ensure their activities are not likely to jeopardize the continued existence of federally listed species or destroy or adversely modify designated critical habitat. 

In 2018, the U.S. Fish and Wildlife Service projected snow loss out to 2050 in two modeling domains (Glacier National Park and the central Rocky Mountains) and found that a decline in spring snow in these areas due to climate change climate change
Climate change includes both global warming driven by human-induced emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale.

Learn more about climate change was likely. The new modeling effort projected snow loss out to the end of the century across five modeling domains that cover more of the breeding range than our modeling in 2018. This new assessment affirmed declines in spring snow due to climate change are likely and that predicted losses will be greater in 2100 than in 2050. 

There is no known snow depth threshold for successful wolverine denning on any date. However, based on historical den site melt-out dates (when there was no snow at the den sites) and historical snow models for Glacier National Park, the 2018 SSA used a snow depth threshold of greater than 0.5 meters on May 1. The Service received concerns from wolverine researchers that using the 0.5 m snow depth threshold on May 1 was not conservative enough based on prior studies (e.g., Copeland et al., 2010; McKelvey et al., 2011) that considered snow depth out to June. Other researchers suggested that snow depth on May 1 is not as important since young wolverine kits are usually out of their natal dens by mid-March. 

The Service addressed the concerns by increasing the snow depth measure representing persistent snow cover to greater than or equal to 1 meter but retained the May 1 end date. This provides a reasonable but more conservative estimate based on the best available information that was used in the 2018 SSA.

Section 4(d) rules provide for conserving a threatened species by tailoring protections to those needed to prevent further decline and support of conservation actions and otherwise lawful activities. First, the Service used these rules to incentivize proactive conservation efforts by streamlining ESA compliance for actions that have long-term benefits but might result in “take” in the short term. Secondly, the Service often uses 4(d) rules to streamline ESA compliance for actions that result in low levels of take but do not threaten a species’ continued existence. 

This approach focuses attention on the threats that individually or cumulatively make a difference to the species' recovery. The exact requirements depend on the species' biology, conservation needs, and threats affecting the species. A 4(d) rule can help maintain and improve a threatened species’ status to help prevent further declines while simultaneously reducing undue regulatory burden. The activities identified (scientific research, forest management activities to reduce the risk or severity of wildfire, and incidental trapping) are not likely to harm the species conservation.

Under the interim 4(d) rule, incidental take caused by forest vegetation management for wildfire mitigation that promotes the long-term stability and diversity of forests is allowed. These forest vegetation and fire management activities include but are not limited to, silviculture practices and forest-management activities that address fuels management, insect and disease impacts, vegetation management in existing utility rights-of-way, and wildlife-habitat management including planting seedlings or sowing seeds, mechanical cuttings as a restoration tool in stands experiencing advancing succession, full or partial suppression of fires, allowing fires to burn, and survey and monitoring of forest health.

Wolverines are occasionally incidentally trapped and killed in the contiguous U.S. in the course of legal trapping for other species, even when such trapping is conducted consistent with state trapping rules that contain steps to minimize the potential for capture of wolverine. This occurs at low levels in a portion of the breeding range and does not currently represent a threat to the wolverine in the contiguous U.S.  at the population or species level.  

Yes. The Service will initially prepare a recovery outline for wolverines in the contiguous U.S. A recovery outline is a brief document that sketches, in broad brushstrokes, the interim conservation and management program for a species during the time between the final listing under the ESA and completion of the recovery plan. 

At this time, critical habitat is not determinable. The Service has an additional year from the publication of the final listing to determine critical habitat designation.

Other species may benefit from the listing of the wolverine. However, the decision to list the wolverine was based solely on the Service’s evaluation of the best available information related to the status of the wolverine in the contiguous U.S. Any potential benefits to other species were not considered in the decision to list the wolverine as threatened.

The wolverine final listing rule, previous federal actions, the 2018 SSA report, and the 2023 SSA report addendum are available at: https://ecos.fws.gov/ecp/species/5123. Since this is a final agency action, the U.S. Fish and Wildlife Service is not seeking public comment on the listing rule. However, the Service is seeking input from the public on the interim 4(d) rule, and comments can be provided through www.regulations.gov, Docket No. FWS–R6–ES–2016–0106. The Service’s decision to affirm or revise this interim rule under section 4(d) will consider all written comments and any additional information.