# Endangered and Threatened Wildlife and Plants; Withdrawal of the Proposed Rule for the North American Wolverine

> Briefs, arguments, decisions, and more.

URL: https://www.frixlaw.com/law-library/documents/fr%3A2020-19538

## Record

- **Collection:** Federal Register
- **Document type:** Proposed Rule
- **Published:** October 13, 2020
- **Citation:** 85 FR 64618

## Text

DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R6-ES-2016-0106; FF09E21000 FXES11110900000 201]
RIN 1018-BB78
Endangered and Threatened Wildlife and Plants; Withdrawal of the Proposed Rule for the North American Wolverine

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Proposed rule, withdrawal.

SUMMARY:

We, the U.S. Fish and Wildlife Service, withdraw the proposed rule to list the distinct population segment (DPS) of the North American wolverine (
Gulo gulo luscus
) occurring in the contiguous United States as a threatened species under the Endangered Species Act of 1973, as amended (Act). This withdrawal is based on our conclusion that the factors affecting the species as identified in the proposed rule are not as significant as believed at the time of the proposed rule. We base this conclusion on our analysis of current and future threat factors. We also find that North American wolverines occurring in the contiguous United States do not qualify as a DPS. Therefore, we are withdrawing our proposal to list the wolverine within the contiguous United States as a threatened species.

DATES:

The proposed rule that published February 4, 2013 (78 FR 7864), to list the distinct population segment of the North American wolverine occurring in the contiguous United States as a threatened species is withdrawn on October 13, 2020.

ADDRESSES:

The withdrawal of our proposed rule, comments, and supplementary documents are available on the internet at
http://www.regulations.gov
at Docket Nos. FWS-R6-ES-2012-0107 and FWS-R6-ES-2016-0106.

FOR FURTHER INFORMATION CONTACT:

Jodi Bush, Field Supervisor, U.S. Fish and Wildlife Service, Montana Ecological Services Office, (see
ADDRESSES
). Persons who use a telecommunications device for the deaf may call the Federal Relay Service at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Executive Summary

Why we need to publish a rule.
Under the Act, if we determine that a species may be an endangered or threatened species throughout all or a significant portion of its range, we are required to promptly publish a proposal in the
Federal Register
and make a determination on our proposal within 1 year. To the maximum extent prudent and determinable, we must designate critical habitat for any species that we determine to be an endangered or threatened species under the Act. Listing a species as an endangered or threatened species and designation of critical habitat can only be completed by issuing a rule.

What this document does.
We withdraw the proposed rule to list the DPS of the North American wolverine occurring in the contiguous United States as a threatened species under the Act.

The basis for our action.
Under the Act, we may determine that a species is an endangered or threatened species because of any of five factors: (A) The present or threatened destruction, modification, or curtailment of its habitat or range; (B) overutilization for commercial, recreational, scientific, or educational purposes; (C) disease or predation; (D) the inadequacy of existing regulatory mechanisms; or (E) other natural or manmade factors affecting its continued existence. We have determined that the factors affecting the species as identified in the proposed rule (loss of habitat due to climate change) are not as significant as believed at the time of the proposed rule. We also find that North American wolverines occurring in the contiguous United States do not qualify as a DPS.

Peer review.
In accordance with our July 1, 1994, peer review policy (59 FR 34270; July 1, 1994), the Service's August 22, 2016, Director's Memo on the Peer Review Process, and the Office of Management and Budget's December 16, 2004, Final Information Quality Bulletin for Peer Review (revised June 2012), we sought the expert opinions of four appropriate specialists regarding the species status assessment report. We received responses from four specialists, which informed this proposed rule. The purpose of peer review is to ensure that our listing determinations are based on scientifically sound data, assumptions, and analyses. The peer reviewers have expertise in the biology, habitat, and threats to the species. Results of this structured peer review process can be found at
https://www.fws.gov/mountain-prairie/science/peerReview.php.
A draft analysis was also submitted to our Federal, State, and Tribal partners for scientific review. In preparing this withdrawal, we incorporated the results of these reviews in the final SSA report, as appropriate.

During the reopening of the public comment periods for the proposed listing rule, we requested any new information and announced that we initiated a new and comprehensive status review of the North American wolverine to determine whether the species meets the definition of an endangered or threatened species under the Act, or whether the species is not warranted for listing. The wolverine SSA report provides the scientific basis for the decision to withdraw the proposed listing rule for the DPS of wolverine occurring in the contiguous United States. Both new and updated information and analyses presented in the wolverine SSA report, summarized below in support of our listing determination, along with public comment, have also prompted us to reevaluate our previous assessment of the DPS with respect to wolverine in the contiguous United States.

Supporting Documents

A team prepared a Species Status Assessment (SSA) for the North American Wolverine (
Gulo gulo luscus
) (Service, 2018) (hereafter referred to as the wolverine SSA report). The SSA team was composed of U.S. Fish and Wildlife Service biologists, who consulted with other species experts. The wolverine SSA report represents a compilation of the best scientific and commercial data available concerning the status of the species, including the impacts of past, present, and future factors (both negative and beneficial) affecting the wolverine. The wolverine SSA report underwent independent peer review by scientists with experience with mesocarnivores and their conservation and management, genetics, population modeling, and climate change. The wolverine SSA report and other materials relating to this proposal can be found on the Mountain-Prairie Region website at
https://www.fws.gov/mountain-prairie/ and at

http://www.regulations.gov
under Docket No. FWS-R6-ES-2016-0106.

Previous Federal Actions

Please refer to the proposed listing rule for the wolverine (78 FR 7864; February 4, 2013) for a detailed description of previous Federal actions concerning the wolverine prior to 2013. On February 4, 2013, we published a proposed rule to list the DPS of wolverine occurring in the contiguous United States as threatened, under the Act, with a proposed rule under section 4(d) of the Act that outlines the prohibitions necessary and advisable for the conservation of the wolverine (78 FR

7864). We also published a proposed rule on February 4, 2013, to establish a nonessential experimental population (NEP) area for the North American wolverine in the Southern Rocky Mountains of Colorado, northern New Mexico, and southern Wyoming (78 FR 7890). On October 31, 2013, we reopened the comment period on the proposed listing rule for an additional 30 days (78 FR 65248).

Following publication of the 2013 proposed rules, there was scientific disagreement and debate about the interpretation of the habitat requirements for wolverines and the available climate change information used to determine the extent of threats to the DPS. Based on this substantial disagreement regarding the sufficiency or accuracy of the available data relevant to the proposed listing, on February 5, 2014 (79 FR 6874), we announced a 6-month extension of the final determination of whether to list the wolverine DPS as a threatened species. We also reopened the comment period on the proposed rule to list the contiguous United States DPS of the North American wolverine for 90 days.

On August 13, 2014, we withdrew the proposed rule to list the DPS of the North American wolverine as a threatened species under the Act (79 FR 47522). This withdrawal was based on our conclusion that the factors affecting the DPS as identified in the proposed rule were not as significant as believed at the time of the proposed rule's publication in 2013. As a result, we also withdrew our associated proposed rule under section 4(d) of the Act contained in the proposed listing rule and withdrew the proposed NEP designation under section 10(j) of the Act for the southern Rocky Mountains.

In October 2014, three complaints were filed in the District Court for the District of Montana by Defenders of Wildlife, WildEarth Guardians, Center for Biological Diversity, and other organizations challenging the withdrawal of the proposal to list the North American wolverine DPS. Numerous parties intervened in the litigation. These three cases were consolidated, and on April 4, 2016, the court issued a decision. The court granted plaintiff's motion for summary judgment with respect to the Service's determination regarding (1) the threat posed to the wolverine by the effects of climate change at the reproductive denning scale, (2) the threat posed to the wolverine by small population size and lack of genetic diversity, and (3) the application of the significant portion of its range policy to the wolverine. As a result of the court order, the August 13, 2014, withdrawal (79 FR 47522) was vacated and remanded to the Service for further consideration consistent with the order. As documented in the SSA report, the Service conducted additional analyses and reviewed new literature regarding climate change effects at the denning scale (see pages 73-99 of the SSA report) and included additional life-history information relevant to this potential stressor (see pages 25-39). With regard to population size, we also provide in the SSA report an analysis of information on wolverine population abundance and distribution (to date) and have included a discussion of population structure (genetics, effective population size) in the context of the species' known genetic variability (see pages 44-50). Finally, in this withdrawal, we have provided an updated significant portion of its range analysis (see discussion below).

In effect, the court's action returned the process to the proposed rule stage, and the status of the wolverine under the Act reverted to that of a proposed species for the purposes of consultation under section 7 of the Act. On October 18, 2016, we published a notice (81 FR 71670) reopening the comment period on the February 4, 2013, proposed rule (78 FR 7864) to list the DPS of wolverine occurring in the contiguous United States as threatened, under the Act. We also requested new information and announced that we initiated a new and comprehensive status review of the North American wolverine, to determine whether the species meets the definition of an endangered or threatened species under the Act, or whether the species is not warranted for listing. The wolverine SSA report provides the scientific basis for the decision to withdraw the proposed listing rule for the DPS of wolverine occurring in the contiguous United States. Both new and updated information and analyses presented in the wolverine SSA report, summarized below in support of our listing determination, along with public comment, have prompted us to reevaluate our previous assessment of the DPS (presented in our 2013 proposed listing rule, which in turn relied on the DPS analysis completed in our 2010 12-month finding) with respect to wolverine in the contiguous United States.

Summary of Comments and Recommendations

As stated above in the Previous Federal Actions section, on October 18, 2016 (81 FR 71670), we opened a public comment period on our February 4, 2013, proposed rule (78 FR 7864) to list the DPS of wolverine occurring in the contiguous United States as threatened. We also contacted appropriate Federal and State agencies, scientific experts and organizations, Tribes, and other interested parties and invited them to comment on the proposed rule. Many of the comments we received from State agencies during our notice for reopening the comment period (81 FR 71670) were similar to those received for the previously proposed rule (78 FR 7864). All substantive information provided during comment periods has either been incorporated directly into this final determination or is addressed below.

Public Comments

(1) Comment:
We received several public comments claiming that the North American wolverine faces increasing threats from the effects of climate change, particularly habitat loss due to declining snow pack.

Our Response:
As discussed in the wolverine SSA report, we recognize that current climate trends and future (2055 and later) climate model projections indicate warming temperatures for much of western North America and changes to snow pack conditions. Our review of the literature found that, overall, higher elevation areas (
e.g.,
Rocky Mountains, Sierra Nevada Mountains) are more resilient to projected changes in temperature and precipitation as compared to lower elevations (Wobus
et al.
2017, p. 12). In general, models indicate higher elevations, where documented historical wolverine denning has occurred, will retain more snow cover than lower elevations, particularly in early spring (April 30/May 1). We present in the wolverine SSA report a summary of new, fine-scale analysis of future snow persistence in two regions of the western United States, Glacier National Park and Rocky Mountain National Park. The two regions studied include a high-latitude area near tree line within Glacier National Park, where tree line occurs at (~1,800 to 2,100 meters (m) (5,906 to 6,890 feet (ft))) that is currently occupied by wolverines; and a lower latitude area within Rocky Mountain National Park (occupied by a single male wolverine from 2009 to at least 2012, but not known to be currently occupied), where tree line occurs at higher elevation (~3,500 m (11,483 ft)) (Ray
et al.
2017, p. 2). These sites were chosen to bracket the range of latitude and elevation wolverines currently occupy in the contiguous United States (Ray
et al.
2017, p. 2). This effort built upon previous model projections presented in McKelvey
et al.
(2011), but with significant differences such as finer

spatial resolution, incorporation of slope and aspect, snow depth estimates, additional years of historical data, and wider temporal analyses of snow persistence (April-June). Details of this modeling exercise are presented in Ray
et al.
(2017), and summarized in the SSA report. That analysis indicates significant areas (several hundred square kilometers (km
2
)/square miles (mi
2
) for each study area) of future snow (greater than 0.5 m (20 inches (in) in depth) will persist on May 1 at elevations currently used by wolverines for denning. This is true, on average, across the range of climate models used out to approximately year 2055.

(2) Comment:
We received several public comments during our request for information claiming that low population size (and small effective population size) warrant listing of the North American wolverine as threatened or endangered.

Our Response:
Small populations in and of themselves do not constitute a threat such that a species would be endangered or threatened. When evaluating species status, we take into consideration the species' life history, population dynamics, and other impacts to populations and species to determine if small population dynamics increases the species' vulnerability to extinction such that listing as threatened or endangered is warranted. Wolverines are difficult animals to survey, and populations occur in naturally low densities across their North American range due, in large part, to their need for large, exclusive territories. At the present time, there is no reliable estimate of the number of wolverines that currently occupy or previously occupied the contiguous United States, nor are there reliable quantitative estimates of wolverine population trends in the contiguous United States. The often-cited population estimate of 318 wolverines (range: 249-626) in the contiguous United States is derived from a habitat modeling exercise presented in Inman
et al.
(2013). That publication also provided a model estimate of potential wolverine capacity of 644 (range: 249-626). However, both of these estimates did not consider important spatial considerations related to wolverine behavior, such as territoriality, relative to wolverine populations. Despite the paucity of information regarding wolverine populations, the SSA analysis is a thorough examination of all of the available population information.

As discussed in the wolverine SSA report, preliminary field results from a recent (2016-2017) occupancy study in four western States (Idaho, Montana, Washington, and Wyoming) and from a pilot occupancy study in Wyoming (2015-2016) indicate detections of wolverines in areas where they would be expected to be found, but also no detections in areas where they are known to occur (
e.g.,
areas within Glacier National Park) (see Service 2018, Appendix B for a descriptive map). To date, this study reports a total of 86 photographic detections through camera-trapping and 157 wolverine hair samples collected for genetic analysis. It has not yet been determined from the camera-trap images or hair samples how many of the detections are unique individuals. Preliminary analysis of the study results indicates an average estimated probability of occupancy of 0.42 suggesting that wolverines used nearly half of all sites during the study period (Montana FWP, pers. comm., 2017); however, the study did not encompass all potential wolverine habitat in the western United States (Service 2018, Appendix B). For example, wolverines have also been recently detected in northeastern Oregon (as of 2017) and in parts of Grand Teton National Park (two records during the winter of 2017), which were not included in the surveyed study cells. Our SSA report presents a visual summary of these recent detections (Service 2018, Figure 3). Although the sum of these reports cannot confirm previous estimates of population size or verify population trends, they offer recent evidence that wolverines continue to be observed across a large area of the western United States.

The 2013 proposed rule presented an effective population size estimate from a publication by Schwartz
et al.
(2009), which estimated a summed effective population size of 35, with credible limits from 28 to 52 (Schwartz
et al.
2009, p. 3,226). As described in the SSA report, the study used wolverine samples from the main part of the Rocky Mountain wolverine populations and did not include subpopulations from two other mountain regions in Montana, and samples were missing from other parts of the wolverine range in Idaho and other areas of Montana. Thus, the analysis missed both wolverine subpopulations and individuals, which would underestimate the results for this type of analysis.

In the wolverine SSA report, we provide a contextual discussion of the effective population size concept, particularly in the context of genetic studies related to the phylogeographic history of the North American wolverine that were not well described in the 2013 proposed rule. In sum, the spatial distribution of genetic variability currently observed in wolverines in North America appears to be a reflection of a complex history in which population abundance has fluctuated since the time of the last glaciation with insufficient time passing since human persecution since at least the 1700s to allow for full recovery of wolverine densities (Cardinal 2004, pp. 23-24; Zigouris
et al.
2012, p. 1,554). This history and the fact that wolverines in the contiguous United States occupy the southern periphery of the species' entire North American range are important considerations in estimating and interpreting current wolverine distribution and abundance. The wolverine SSA report also presents information from genetic and observational studies that provide support for wolverine movement across the international border of the contiguous United States and Canada. In the 2013 proposed rule, we stated there is an apparent lack of connectivity between wolverine populations in Canada and the United States based on genetic data (78 FR 7864; February 4, 2013). We now consider wolverines that occupy the contiguous United States to be genetically continuous with wolverines in adjacent Canadian provinces. A small effective population size would be more of a concern if the population was in isolation; however, wolverines in the contiguous United States are not genetically isolated from wolverines in Canada. For more information, see the
Small Total Population Size
and
Effective Population Size
sections under Distinct Population Segment below.

(3) Comment:
We received several public comments during our request for information claiming that North American wolverine face threats from indiscriminant trapping in the contiguous United States, or are threatened by incidental trapping.

Our Response:
At the present time, trapping or hunting of wolverine is not allowed in any State within the range of the wolverine (with the exception of Alaska). Legal protections for wolverines are codified in western State laws and regulations and include: Endangered in Colorado, threatened in California and Oregon, candidate species in Washington, non-game species protections in Idaho and Wyoming, a species of concern and a furbearer with a closed season in Montana, and protection from collection, importation, and possession in Utah. Since 2013, there has been a zero quota for trapping or harvest of wolverine in Montana.

Incidental trapping of wolverines has been documented in the contiguous

United States (as recently as December 2017), though not all events have resulted in mortality. In the wolverine SSA report, we provide a summary of the number of wolverines that have been incidentally trapped in Idaho (18 since 1965, including 6 known to be released alive and 7 known mortalities), Montana (4 since 2013, 3 mortalities and 1 released unharmed), and Wyoming (2 since 1996, 1 mortality and 1 released unharmed) (Service 2018, p. 66). Both Idaho and Montana are implementing trapper education programs to minimize nontarget wolverine captures.

As discussed in the SSA report, regulated trapping and hunting of wolverines occurs in parts of Alaska and Canada, and appears to be sustainable based on population and density estimates.

(4) Comment:
We received several public comments identifying potential threats to wolverines from winter recreation activities, such as snowmobiling and back-country skiing.

Our Response:
In the SSA report, we present a summary of winter recreation studies (Heinemeyer
et al.
2015; Heinemeyer
et al.
2017), future projections of winter recreation activity in the contiguous United States (White
et al.
2014), and projections of snowpack relative to changes in the length of the winter recreation season (Wobus
et al.
2017). We reported results from Heinemeyer (2016, pers. comm.) indicating a behavioral response to recreation activities, but also maintenance of home ranges within some areas of relatively high recreation activity over several years. The study has not yet been able to determine whether resident wolverines are reproductively successful due to the limited monitoring information available for reproducing female wolverines. Nor was the study able to determine if recreational activities had a negative impact on wolverine reproductive success.

We also note here that we received the final report of this multiyear study (Heinemeyer
et al.
2017) in mid-December 2017 (results of this study were recently published (Heinemeyer
et al.
2019)), which was after we submitted the draft SSA report for review to four peer reviewers and to our State, Federal, and Tribal partners. Much of the report presents a modeling exercise to evaluate wolverine behavior patterns with winter recreation activities. The study found that wolverines maintained multiyear home ranges, and the authors suggest that wolverines are able to tolerate winter recreation at some scales (Heinemeyer
et al.
2017, p. iv; Heinemeyer
et al.
2019, p. 16). The study described habitat selection as complex for female wolverines and was likely driven by a combination of abiotic (snow, cold) and biotic (predator avoidance, food availability) factors (Heinemeyer
et al.,
2017, p. 36; Heinemeyer
et al.
2019, p. 16). This study did not assess demographic effects, fitness effects, or population level effects of winter recreation on wolverines (Heinemeyer
et al.
2019, p. 17 and 19). As discussed in the wolverine SSA report, management measures being implemented in areas within the wolverine's current extent of occurrence include road closures to minimize disturbance to wildlife on lands managed by the U.S. Forest Service and National Park Service (Service 2018, p. 61 and Appendix F). In addition, management strategies are identified in State Wildlife Action Plans (
e.g.,
Oregon, Montana, Idaho) to address potential impacts from recreation to the wolverine. Although we did not rely on these conservation measures to support our decision, they do provide some level of protection to address potential impacts from disturbance from winter recreation activity and mortality from roads.

(5) Comment:
We received public comments claiming that wolverines are dependent on deep snow for survival and expressing concern for future changes in snow pack due to the effects of climate change.

Our Response:
After reviewing studies not previously considered and the results of new studies/publications made available after the 2013 and 2014 proposed rules (
e.g.,
Aronsson 2017, Aronsson and Persson 2016, Aronsson
et al.
2017, Magoun
et al.
2017, Persson
et al.
2017, Stewart
et al.
2016, Webb
et al.
2016, see complete list of citations in the wolverine SSA report), we present in the SSA report a detailed discussion of the North American wolverine's physiology and other life-history characteristics (
e.g.,
reproductive behavior). This summary speaks to several presumed aspects of the relationship of denning behavior and other needs of this species regarding the presence of persistent spring snow. As summarized below, we now know that wolverines can and have denned outside of heavy snowpack, multiple factors play a role in den site selection, females will move dens as young become mobile, and areas of significant snowpack will likely persist in the future in areas where wolverines are known to den at levels that will continue to support wolverines.

Denning habitat for the wolverine varies over its range and is dependent on local and regional environmental conditions (
e.g.,
topographic and other structural features) and biotic (
e.g.,
availability of prey; protection from predators) factors. Reproductive (natal) dens are not always excavated in deep snow, particularly in boreal forest habitats (Dawson
et al.
2010; Novikov 1962; Webb
et al.
2016; Jokinen 2019.), and have been observed in spruce tree root balls, logging slash piles, and beaver dens/dams. In the contiguous United States, dens are found at high elevations, often in talus slopes, which provides conditions for protection and food caching (
e.g.,
restricted access and cold temperatures). Our review of studies of wolverine denning activity found no quantitative data reporting snow depth at the den site when wolverines abandon the den. More importantly, wolverine reproductive success has not been studied relative to a number of abiotic and biotic conditions, including depth and temporal aspect of spring snow cover.

Wolverines begin shifting den locations in late April, when young become more mobile and reliant on solid food brought to them by the mother (Aronsson 2017, p. 46; Aubry
et al.
2016, p. 24). The bioclimatic model presented in Copeland
et al.
(2010) was used to test wolverine distribution at a broad scale based on climate variables, including spring snow cover, using May 15 conditions. They then tested their hypothesis by comparing and correlating the location of wolverine dens across their circumboreal range, and telemetry locations from wolverine studies in North America and Scandinavia (Copeland
et al.
2010, p. 234). Since that publication, wolverines and wolverine dens have been observed outside the boundaries defined by the model presented in Copeland
et al.
(2010) (
e.g.,
Webb
et al.
2016, Webb 2017 pers. comm., Persson 2017, pers. comm.). While these observations are found at higher latitudes in the circumboreal region, they also indicate wolverines and wolverine dens are observed in environments that are not characterized by several feet of spring snow on May 15. In sum, Copeland
et al.
(2010) provided a fairly accurate assessment of where wolverine populations are expected to occur, but it did not evaluate (model) snow persistence at the den site scale based on location and denning period.

In the SSA report, we present an analysis of 34 wolverine den locations (years 2002-2015) from studies in the western contiguous United States relative to “melt out” dates, which represents the first day of an 8-day satellite (Moderate Resolution Imaging

Spectroradiometer (MODIS)) composite of when the den switches from “snow” to “no snow” at a 500-by-500-m (1,640-by-1,640-ft) spatial resolution. For natal den locations, the range of the melt-out dates was from May 25 to June 12, which is considerably later than the May 15 date used in the Copeland
et al.
(2010) analysis. The estimated melt-out dates indicate that snow is persistent at these locations past the time when young wolverines are generally moving out of natal dens (
i.e.,
late April).

The Copeland
et al.
(2010) snow model was then used by McKelvey
et al.
(2011) to model effects of climate change to wolverine habitat in the western United States to develop projections of habitat loss. This modeling exercise used May 1 snow presence as a proxy for May 15 snow disappearance and a spatial resolution of 36.3 km
2
(14 mi
2
)), which is not relevant at the at the den site scale. As described in our Response to Comment #1, in the SSA report, we presented a finer scale analysis (0.0625 km
2
(0.24 mi
2
)) for two study areas (Glacier National Park and Rocky Mountain National Park) that focused directly on May 15, in addition to the presence or absence of snow on May 1 and April 15 in our evaluation of the effects of climate change to snowpack. These dates are more relevant to wolverine life-history needs. We also modeled the depth of “significant” snow (0.5 m (1.64 ft)) on these dates. We found that large areas (several hundred km
2
/mi
2
for each study area) of future snow (greater than 0.5 m (20 in) in depth) are projected to persist on May 1 at elevations currently used by wolverines for denning. This is true, on average, across the range of climate models used out to approximately year 2055. We recognize that wolverines are difficult to study and evaluation of denning habitat and behavior is challenging. Additional research is needed to evaluate other potential physical and biotic variables that could be important in defining wolverine distribution and den locations. These additional variables include: prey availability, risk of predation, den-site scale factors such as structure/snow conditions, and temporal use of dens.

(6) Comment:
We received public comments identifying the need for additional research and recommendations for conservation measures for the North American wolverine, including estimates of population size and further evaluation of life-history characteristics, and recommendations for conservation measures.

Our Response:
We appreciate the comments acknowledging the need for additional studies as well as the difficulties in studying wolverines given its occupation of remote habitats in the contiguous United States. In the wolverine SSA report, we provide a summary of the preliminary field and genetic results from the recent Western States Wolverine Conservation Project (WSWCP)-Coordinated Occupancy Study in four western (contiguous United) States, as well as results from several new studies presented in peer-reviewed publications and in other reports from Canada and Scandinavia. As discussed in the SSA report, the Western States Wolverine Working Group is continuing to develop studies to evaluate wolverine population distribution and occupancy, and connectivity across four western States.

(7) Comment:
We received additional comments from the public including the need for collaboration with local government and community stakeholders and use of best available science in developing the proposed rule.

Our Response:
During our preparation of the wolverine SSA report, we coordinated extensively with many wolverine researchers in the United States (including Alaska), Canada, and Scandinavia. Those communications are identified in our References Cited section of the wolverine SSA report. Their expertise, insights, and published or soon-to-be published research papers were invaluable in ensuring that we used the best available science in preparing the new status review. We also communicated with biologists at several State and Federal agencies to ensure that we had incorporated the most recent wolverine detections in the western United States. The wolverine SSA report was sent to four independent peer reviewers, selected by an outside contractor, and those non-attributable comments were incorporated, to the extent possible, in the final document. We also reviewed comments received from the public and previous peer reviewers during our request for comments for our previous proposed rule and considered the information provided (78 FR 7864; February 4, 2013) during the preparation of the wolverine SSA report. As a result, this determination is based upon the best scientific and commercial data available to us, as required by the Act.

(8) Comment:
We also received public comments recommending that the North American wolverine not be listed as threatened or endangered under the Act. One commenter stated that State wildlife agencies are capable of managing the species and are able to provide protections that ensure continued population growth towards population objectives established by these agencies and that mandates of various Federal resource management agencies provide a commitment to managing wildlife habitat in a way that benefits all wildlife species, including wolverines and other forest carnivores.

Our Response:
We acknowledge that some members of the public support our decision to withdraw our proposed rule to list the North American wolverine as threatened under the Act. In the wolverine SSA report (Service 2018, Appendix G), we provide a summary of the regulatory protections provided by western States and Federal agencies as well as management measures being implemented to conserve the wolverine and its habitat. Legal protections in the contiguous United States include State listing in California and Oregon (threatened), endangered in Colorado, a candidate species in Washington, non-game species protections in Idaho and Wyoming, a species of concern and furbearer with a closed season in Montana, and protection from collection, importation, and possession in Utah. Trapping or hunting of wolverines is currently prohibited in the contiguous United States.

(9) Comment:
In response to our request for information in our public notice, several members of the public provided specific information related to personal wolverine sightings of the North American wolverine in the contiguous United States (
e.g.,
New Mexico, Wyoming), and information regarding past and ongoing research studies of the species in the western United States and in Canada.

Our Response:
We appreciate the personal observations provided and encourage members of the public to document sightings of the North American wolverine with photographs and provide additional details to State wildlife agencies. Information we received regarding results from research studies has been incorporated, as appropriate, in the final wolverine SSA report.

(10) Comment:
We received comments from several organizations that support the listing of the North American wolverine and designation of critical habitat. Threats cited include concerns related to migration, habitat loss and connectivity related to threats from effects of climate change, nontarget trapping pressures, road mortality and other effects of roads (
e.g.,
noise, pollution, fragmentation of habitat), motorized recreation and traffic in wildlife corridors, timber sales and

associated roads, and effects of snowmobile traffic (habitat fragmentation and pollution, and change in behavior).

Our Response:
As discussed in the
Risk Factors for the North American Wolverine
section below, we identified several potential stressors that may be affecting the species and its habitat currently or in the future, including impacts associated with climate change effects. We recognize there is limited information available for the wolverine, including population estimates and abundance trends. Based on the best available information, demographic risks to the species from either known or most likely potential stressors (
i.e.,
disturbance due to winter recreational activities, other human disturbances, effects of wildland fire, disease, predation, overutilization, genetic diversity, small population effects, climate change, and cumulative effects) are low based on our evaluation of the best available information as it applies to current and potential future conditions for the wolverine and in the context of the attributes that affect the needs of the species (Service 2018, p. 103). Thus, we determined that, based on the best available information, the North American wolverine in the contiguous United States does not meet the definition of a threatened species or an endangered species under the Act.

(11) Comment:
We received public comments stating that protection of North American wolverines in the contiguous United States is needed under the Act in order to provide resources and attention needed for research and monitoring, to better understand threats, and sustain wolverines into the future. The commenter also stated that federally sponsored wolverine reintroduction in Colorado will help increase chances of long-term species survival.

Our Response:
We appreciate the recognition of the need for continued resources for research and monitoring. However, we base our listing decisions on a determination of whether the species meets the Act's definitions of a threatened species or an endangered species. Regardless, as summarized in the SSA report, in 2015, State wildlife agencies in Idaho, Montana, Washington, and Wyoming, along with Federal, tribal, and nongovernmental organization partners, developed a collaborative and coordinated monitoring program to be implemented in a coordinated fashion across the species' range in the western United States. In 2015, the State of Wyoming contracted with the Wolverine Initiative to conduct the Wyoming Wolverine Occupancy Pilot Study to address questions pertaining to the status and distribution of wolverines throughout the Greater Yellowstone Ecosystem and the Bighorn Mountains in the winter of 2015-2016. Expanding on this study, the Western States Wolverine Working Group designed and implemented the WSWCP-Coordinated Occupancy Survey in the winter of 2016-2017, and preliminary results are presented in the SSA report. The Western Association of Fish and Wildlife Agencies (WAFWA) Wildlife Chiefs Wolverine Subcommittee (formally endorsed in 2014) currently provides a forum for western States to work collaboratively with each other and with the Service, Tribes, and other partners, for conserving wolverines across the western United States. To date, approximately $1.5 million of that funding has been applied towards conservation and management actions, including the WSWCP (McDonald 2017, pers. comm.). This group is also developing a connectivity study project to support conservation planning efforts for the Rocky Mountains and North Cascades regions.

In addition, multiple western States have identified the North American wolverine as a Species of Greatest Conservation Need in their State Wildlife Action Plans, and the North American wolverine is a focal species of conservation strategies for conservation targets in a number of ecoregions (
e.g.,
Cascades, Sierra Nevada) that support forested lowlands, subalpine-high montane conifer forest where wolverines occur. These State designations provide information to assist resource managers with proactive decision making regarding species conservation and data collection priorities. Finally, the Nez Perce Tribe is currently preparing an Integrated Resource Management Plan, a Plant and Wildlife Conservation Strategy, and a Forest Management plan with the wolverine defined as a species of conservation concern in all three draft plans (Miles 2017, pers. comm.).

In total, these funded and volunteer collaborative, landscape-level conservation efforts ensure continued support for the conservation of the North American wolverine. Although we did not rely on these plans to support our decision, we recognize that these plans, when implemented, will likely benefit wolverines and their habitat.

(12) Comment:
We received comments from several industry groups supporting our August 13, 2014, withdrawal (79 FR 47522) of our February 4, 2013, proposed rule (78 FR 7864) to list the North American wolverine as threatened. In general, their support rests on the following: (1) The DPS determination presented in our previous proposed rules (both 2010 and 2013) was flawed; (2) the North American wolverine does not meet the definition of a threatened species; (3) the obligate relationship with denning and need for snow has not been adequately addressed (and may be a habitat preference); and (4) climate model projections do not support complete loss of snow. They also urged us to reaffirm prior findings that winter recreation (motorized and nonmotorized) is not a threat to wolverines.

Our Response:
Given that our updated analysis and new information included in the wolverine SSA report directly relates to our previous DPS determination in the 2013 proposed rule, we reevaluated wolverines in the contiguous United States under our DPS Policy. See the Distinct Population Segment section below for more information. We provide our analysis of the status of wolverines in the contiguous United States below in the Determination of Species Status. The topic of denning behavior is discussed in the wolverine SSA report (see Use of Dens and Denning Behavior discussion in the
Reproduction and Growth
section in the wolverine SSA report (Service 2018, pp. 23-28)). For our analysis of the effects of climate change to wolverines and denning habitat, see
Climate Change and Potential for Cumulative Effects
below.

(13) Comment:
We received a comment from an industry group stating that our decision to prepare the February 4, 2013, proposed rule (78 FR 7864) to list the North American wolverine as threatened was due to a “misreading” of the Service's obligation under our 2011 Settlement Agreement, and therefore the proposed rule was not developed from “an open-ended scientific inquiry.” We received a comment from an industry group stating that the Service should not “revert back to the 2013 proposed rule” and should conduct a new analysis of potential impacts to the species, revise the proposed listing using newly available information, and reevaluate our previous DPS determination.

Our Response:
The Service properly prepared its 2013 proposed rule. On October 18, 2016, we published a document in the
Federal Register
(81 FR 71670) announcing that we would initiate a new status review of the North American wolverine, to determine whether this DPS meets the definition of an endangered or threatened species

under the Act, or whether the species is not warranted for listing. The Service has prepared the wolverine SSA report that includes discussion and analyses of the best available scientific information regarding life history, biology, and consideration of current and future vulnerabilities. This information was used to evaluate the current and future conditions of the species, and to inform our current determination.

Comments From Tribes

(14) Comment:
We received comments from one consortium of Tribal nations stating that, based on the weight of evidence provided in our previous rules, the North American wolverine meets the definition of endangered or threatened and is therefore warranted for listing. Specific threats mentioned in the comment letter included current population status, winter recreation activities, and effects of climate change. The Tribes also included comments documenting the cultural value of the wolverine and connection to cultural practices and concern for the loss of wolverine populations in the contiguous United States. The Tribes encouraged the Service to use sound and solid science in the listing determination, and noted that additional population monitoring and Tribal climate change modeling efforts are under way to evaluate the status of the wolverine.

Our Response:
We appreciate the unique perspective provided by the Tribal nations regarding the contribution of the North American wolverine to the Tribes' culture and spirituality. We also appreciate the commitment of the Tribal nations to continue ongoing studies of wolverines.

As described in the wolverine SSA report, we evaluated new information, as well as information not previously considered, and contacted several wolverine researchers (both within and outside the United States) to provide a more detailed description of the wolverine's life history and ecology, including a detailed discussion of wolverine denning habitat and behavior. We conducted new analyses to develop a current potential extent of occupancy using the most recent verified observations. Current potential extent is the perimeter of the outermost geographic limits based on all (available) occurrence records (that is, the maximum extent of occurrences) of a species minus those areas where we believe the species has been extirpated (Service 2017). Conservation measures and regulatory mechanisms relative to the wolverine were also provided in the wolverine SSA report. This information was used to evaluate the current (potential stressors) and future conditions of the species, and inform our current determination. We evaluated results from a fine-scale analysis of the potential effects of climate change to future snowpack conditions in two regions of the Rocky Mountains. This analysis found that significant areas (several hundred km
2
/mi
2
) will persist on May 1 at elevations used by wolverines for denning. We determined that, based on the best available information, the North American wolverine in the contiguous United States does not warrant listing as threatened or endangered under the Act.

(15) Comment:
We received comments from one Tribe whose aboriginal territory is occupied by the North American wolverine. The Tribe submitted a comment letter in 2013 supporting our proposed listing. The Tribe stated that the conservation and restoration of the wolverine and other species within this homeland is of great importance to the Tribe's subsistence, culture, religion, and economy. The letter also identified conservation and management plans currently under development and highlighted that the wolverine is designated as a species of concern in these current draft plans. Specific comments were provided relative to threats from climate change (including relative to demographic stochasticity), recreation and urban development, and incidental take. Included in those comments were references to other studies under way (
e.g.,
Adaptation Partners and climate change vulnerability assessments; winter recreation study) to evaluate these potential stressors.

Our Response:
We appreciate the perspective provided regarding the importance of the wolverine and other species to the Tribe and its commitment to current and future conservation and management actions. We also appreciate and evaluated the information presented in the citations that were provided in the comment letter. As described in the wolverine SSA report, we evaluated several new scientific publications and information not previously considered in preparing a new status review. This information was used to evaluate the current conditions (
i.e.,
potential stressors, including winter recreation) and future conditions (
e.g.,
effects of climate change) of the species. Based on the best available information, we determined that the North American wolverine in the contiguous United States does not warrant listing as threatened or endangered under the Act.

State Agency Comments

We received extensive comments from several western States, requesting that we consider previously submitted comments in response to our previously proposed listing rule (78 FR 7864; February 4, 2013) as well as additional comments submitted in response to our 2016 notice reopening public comment (81 FR 71670; October 18, 2016). These comments were grouped together and summarized as described below:

(16) Comment:
We received detailed comments critical of our reliance on “unverified” climate model projections in our 2013 proposed rule, the lack of discussion of assumptions in adopting the model findings, the lack of evaluating alternative hypotheses, and the need to evaluate these effects at the den-site scale. One State agency recommended that, given the disagreements in the scientific community on the interpretation of these results, the Service solicit an independent, scientific review of the proposed rule.

Our Response:
This withdrawal was based on the scientific analysis using the structure of the Service's Species Status Assessment (SSA) Framework (
https://www.fws.gov/endangered/improving_ESA/ssa.html
). An SSA is a focused and rigorous assessment of a species' ability to maintain self-sustaining populations over time. This assessment is based on the best available scientific and commercial information regarding life history, biology, and consideration of current and future vulnerabilities. The result is a single document (SSA report) that delivers foundational science for informing decisions under the Act, including listing determinations, consultations, grant allocations, permitting, and recovery planning.

In preparing the final SSA report for the North American wolverine (available at
www.regulations.gov,
at Docket No. FWS-R6-ES-2016-0106), we reviewed available reports and peer-reviewed literature, incorporated survey information for the purpose of preparing updated maps of the known species' current and historical occurrences, and contacted species experts to collect additional unpublished information. We evaluated the appropriate analytical tools to address data gaps and uncertainties. In some instances, we used publications and other reports of the Eurasian subspecies (
Gulo gulo gulo
) to fully inform our knowledge of the North American wolverine (
Gulo gulo luscus
).

Before finalizing the SSA report, the draft wolverine SSA report was

submitted for peer review to four independent peer reviewers in accordance with our July 1, 1994, peer review policy (59 FR 34270), the Service's August 22, 2016, Director's Memo on the Peer Review Process, and the Office of Management and Budget's December 16, 2004, Final Information Quality Bulletin for Peer Review (revised June 2012). Results of this structured peer review process can be found at
https://www.fws.gov/mountain-prairie/science/peerReview.php.
This draft was also submitted to our Federal, State, and Tribal partners for scientific review. In preparing this determination to withdraw the proposed rule, we incorporated the results of these reviews in the final wolverine SSA report, as appropriate.

As noted in our previous responses to public comments (see response to
Comments 1
and
5
above), in our wolverine SSA report, we recognize that current climate trends and future (2055 and later) climate model projections indicate warming temperatures for much of western North America, and changes to snow pack conditions. Our review of the literature found that, overall, higher elevation areas (
e.g.,
Rocky Mountains, Sierra Nevada Mountains) are more resilient to projected changes in temperature and precipitation as compared to lower elevations (Wobus
et al.
2017, p. 12). In general, models indicate higher elevations will retain more snow cover than lower elevations, particularly in early spring (April 30/May 1). We present in the wolverine SSA report a summary of new, fine-scale analysis of future snow persistence in two regions of the western United States, Glacier National Park and Rocky Mountain National Park. Glacier National Park represents a high-latitude and relatively low-elevation area currently occupied by North American wolverines. Rocky Mountain National Park is a lower latitude and high-elevation area within the North American wolverine's historical range, which was occupied by a male wolverine from 2009 to at least 2012.

As described above in
Comment 5,
this new analysis built upon previous model projections presented in McKelvey
et al.
(2011), but with significant differences such as finer spatial resolution, incorporation of slope and aspect, snow depth estimates, additional years of historical data, and wider temporal analyses of snow persistence (April-June). Details of this modeling exercise are presented in Ray
et al.
(2017), and summarized in the wolverine SSA report. That analysis indicates large areas (several hundred km
2
/mi
2
for each study area) of future snow (greater than 0.5 m (20 in) in depth) will persist on May 1 at elevations currently used by wolverines for denning. This is true, on average, across the range of climate models used out to approximately year 2055.

After reviewing studies not previously considered and new studies/publications made available after the 2013 and 2014 proposed rules, we present in the wolverine SSA report, a detailed discussion of the North American wolverine's physiology and other life-history characteristics (
e.g.,
reproductive behavior). The analysis speaks to several presumed aspects of the relationship of denning behavior and other needs of this species regarding the presence of persistent spring snow.

Also, see our response to
Comment 5
above for a short summary and our SSA report for more details regarding our analysis of the effects of climate change to denning habitat.

(17) Comment:
We received comments critical of our previous support for findings by Schwartz
et al.
2009 regarding effective population size. Relatedly, several States commented on recent dispersal/movements of wolverines into California, Colorado, and Utah as evidence of population expansion.

Our Response:
See our response to
Comment 2
above for a discussion of effective population size. Regarding recent occurrences of wolverines in the contiguous United States, wolverines have recently been found in areas where they were once extirpated in the contiguous United States. See the Population Abundance and Density section below for more information.

(18) Comment:
We received comments from several western States presenting clarifications or updates to incidental trapping events and trapping regulations.

Our Response:
In the wolverine SSA report, we include a summary of trapping or hunting of wolverines in the contiguous United States. At the present time, trapping or hunting of wolverines is not allowed in any western State (with the exception of Alaska, which was not included in the DPS in our proposed rule). Legal protections for wolverines are codified in western State laws and regulations concerning hunting and trapping. These protections include: Endangered in Colorado, threatened in California and Oregon, candidate species in Washington, non-game species protections in Idaho and Wyoming, a species of concern and furbearer with a closed season in Montana, and protection from collection, importation, and possession in Utah. Since 2013, there has been a zero quota for trapping or harvest of wolverine in Montana.

Incidental trapping of wolverines has been documented in the contiguous United States (as recently as December 2017), though not all events have resulted in mortality (see response to
Comment
3 above). Both Idaho and Montana are implementing trapper education programs to minimize nontarget wolverine captures.

(19) Comment:
Several States provided comments in response to our 2013 proposed rule and to our 2016 reopening of the public comment period indicating their disagreement with our determination of a DPS for the contiguous United States. Specifically, some commenters stated that the criteria of significance should be reevaluated, noting that the proposed rule did not provide any substantive information to support our conclusion that the loss of the wolverine in the contiguous United States would result in a significant gap in the range of the species; that is, our previous use of the loss of latitudinal range does not provide a rational basis for concluding that the loss of the wolverine in the contiguous United States would be significant in relation to the taxon. Another commenter stated that the wolverine population in the contiguous United States is connected geographically and genetically to the Canada/Alaska populations and these northern populations were likely the source of recolonization during the 20th century. Further, this commenter stated there is not a difference in control of exploitation and conservation status between the United States and Canada.

Another commenter noted that, throughout the 2013 proposed rule, the Service acknowledged that, historically, the wolverine population in the contiguous United States was markedly reduced by systematic predator control programs and unregulated trapping. Yet, as the commenter pointed out, areas of suitable habitat in the North Cascades, where trapping has been minimal or nonexistent for decades, and northern Rockies, were recolonized by animals from Canada, where relatively liberal trapping is still allowed. Thus, our characterization in the 2013 proposed rule of “liberal” Canadian regulations as sufficient to “maintain the robust conservation status of the Canadian population,” does not comport with our characterization that the very limited trapping in the contiguous United States (Montana only) is insufficient to maintain the rebounding population designated as a DPS.

Our Response:
In light of the updated analysis and new information included in the wolverine SSA report, we reevaluated wolverines in the contiguous United States under our DPS Policy. We conclude that the population of wolverines in the contiguous United States is not discrete in relation to the remainder of the species in North America. As a result, the population of wolverines in the contiguous United States is not a listable entity under section 3(16) of the Act. See the Distinct Population Segment section below for more information.

(20) Comment:
State agencies provided citations or copies of publications and reports relevant to wolverine ecology that were published after the 2013 proposed rule.

Our Response:
We appreciate the comprehensive lists of published literature and survey reports provided by the State agencies. We evaluated this information during the preparation of the wolverine SSA report, and have incorporated this information, as appropriate, to ensure that the wolverine SSA report presents the best available information regarding the status of the North American wolverine.

(21) Comment:
We received information providing background information and preliminary results of ongoing collaborative conservation efforts being implemented through the WSWCP-Coordinated Occupancy Survey.

Our Response:
We appreciate the additional information provided by the State agencies participating in the WSWCP-Coordinated Occupancy Study. In the wolverine SSA report, we provide a summary of the preliminary field and genetic results from the recent WSWCP-Coordinated Occupancy Study in four western (contiguous United) States (see wolverine SSA report for additional details). We also incorporated technical comments received from several State agencies during the review of the draft wolverine SSA report into the final report. As discussed in the wolverine SSA report, the Western States Wolverine Working Group is continuing to develop studies to evaluate wolverine population distribution and occupancy, and connectivity across four western States.

(22) Comment:
Information was provided by State agencies describing the legal protections of wolverines in individual States and conservation measures being implemented.

Our Response:
In the wolverine SSA report (Service 2018, Appendix G), we provide a detailed discussion of current State (and Federal) regulatory mechanisms and other conservation measures that offer protections for the North American wolverine. In addition to the WSWCP-Coordinated Occupancy Study (Service 2018, Appendix B), several western States have identified the North American wolverine as a Species of Greatest Conservation Need in their State Wildlife Action Plans, and the North American wolverine is a focal species of conservation strategies for conservation targets in a number of ecoregions (
e.g.,
Cascades, Sierra Nevada) that support forested lowlands, subalpine-high-montane conifer forest where wolverines occur. These State designations provide information to assist resource managers with proactive decision-making regarding species conservation and data collection priorities, and support the conservation of the North American wolverine and its habitat.

(23) Comment:
We received a comment from one State agency noting that the State does not recognize the North American wolverine as a native species due to lack of evidence that a population ever existed within New Mexico (
i.e.,
unverified species); thus, the State does not recognize the species in any of its wildlife statutes or regulations.

Our Response:
We appreciate the clarification and information provided by the State agency and have considered this in our analysis to define the current potential extent of occurrence for the North American wolverine in the contiguous United States (see Figures 1 and 2 below) and in our assessment of population status in the wolverine SSA report. In their analysis of wolverine distribution records in the contiguous United States, Aubry
et al.
(2001, p. 2,150) identified 1860 as the most recent verifiable documentation of wolverine in northern New Mexico. We received two unverified accounts of wolverine sightings in New Mexico from the general public during the most recent public comment period. We are unaware of any recent verifiable individuals or populations of wolverines in New Mexico.

(24) Comment:
In response to our request for information in our October 18, 2016,
Federal Register
document (81 FR 71670), we received comments from the U.S. Forest Service submitting verifiable and new records of wolverines from 2000 to 2016. These records include observations from camera surveys by both governmental and nongovernmental organizations, photos from private citizens, and locations from a regional study.

Our Response:
We appreciate the information provided and incorporated these observations and detections in our analysis to define the current potential extent of occurrence for the North American wolverine in the contiguous United States (see Figures 1 and 2 below) and in our assessment of population status in the wolverine SSA report.

Background

A comprehensive review of the life history, population trends, and ecology of the North American wolverine is presented in the wolverine SSA report (Service 2018, pp. 3-44). The Service recognizes the North American wolverine as the subspecies
Gulo gulo luscus
(Service 2018, p. 8). Wolverines are a medium-sized (about 1 m (3.3 ft) in length) carnivore, with a large head, broad forehead, and short neck (Service 2018, p. 4). Wolverines have heavy musculature and relatively short legs, and large feet with strong, curved claws for digging and climbing (Service 2018, p. 4). Their feet are adapted for travel through deep snow and, during the winter, dense, stiff, bristle-type hairs are found between the toes and around the foot pad; this characteristic becomes diminished in the summer (Service 2018, p. 4). The wolverine is the largest terrestrial member of the Mustelidae family (weasels, fisher, mink, marten, and others) and resembles a small bear with a bushy tail (Service 2018, p. 1). Wolverines possess a number of morphological and physiological adaptations that allow them to travel long distances and they maintain large territories in remote areas (Service 2018, p. 1). They have been described as curious, intelligent, and playful, but cautious animals, though their social behavior and social organization has not been well-studied (Service 2018, p. 1). Wolverines have a distribution that includes the northern portions of Europe, Asia, and North America. In North America, they are found in Alaska, much of Canada, and the western-northwestern United States.

During the late 1800s and early 1900s, the wolverine population declined or was extirpated in much of the contiguous United States (lower 48 States), which has been largely attributed to unregulated trapping (Hash 1987, p. 583). Wolverine numbers have recovered to some extent from this decline and, in the United States, wolverines are currently found in parts of Washington, Oregon, Idaho, Montana, Wyoming, California (single male), and Alaska, and as recently as 2010 in Michigan, 2012 in Colorado, and 2016 in Utah. Known reproducing wolverine populations are found in Washington, Idaho, Montana, and Wyoming (Service 2018, p. 1).

Regulatory and Analytical Framework

Regulatory Framework

Section 4 of the Act (16 U.S.C. 1533) and its implementing regulations (50 CFR part 424) set forth the procedures for determining whether a species is an “endangered species” or a “threatened species.” The Act defines an endangered species as a species that is “in danger of extinction throughout all or a significant portion of its range,” and a threatened species as a species that is “likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.” The Act requires that we determine whether any species is an “endangered species” or a “threatened species” because of any of the following factors:

(A) The present or threatened destruction, modification, or curtailment of its habitat or range;

(B) Overutilization for commercial, recreational, scientific, or educational purposes;

(C) Disease or predation;

(D) The inadequacy of existing regulatory mechanisms; or

(E) Other natural or manmade factors affecting its continued existence.

These factors represent broad categories of natural or human-caused actions or conditions that could have an effect on a species' continued existence. In evaluating these actions and conditions, we look for those that may have a negative effect on individuals of the species, as well as other actions or conditions that may ameliorate any negative effects or may have positive effects.

We use the term “threat” to refer in general to actions or conditions that are known to or are reasonably likely to negatively affect individuals of a species. The term “threat” includes actions or conditions that have a direct impact on individuals (direct impacts), as well as those that affect individuals through alteration of their habitat or required resources (stressors). The term “threat” may encompass—either together or separately—the source of the action or condition or the action or condition itself.

However, the mere identification of any threat(s) does not necessarily mean that the species meets the statutory definition of an “endangered species” or a “threatened species.” In determining whether a species meets either definition, we must evaluate all identified threats by considering the expected response by the species, and the effects of the threats—in light of those actions and conditions that will ameliorate the threats—on an individual, population, and species level. We evaluate each threat and its expected effects on the species, then analyze the cumulative effect of all of the threats on the species as a whole. We also consider the cumulative effect of the threats in light of those actions and conditions that will have positive effects on the species, such as any existing regulatory mechanisms or conservation efforts. The Secretary determines whether the species meets the definition of an “endangered species” or a “threatened species” only after conducting this cumulative analysis and describing the expected effect on the species now and in the foreseeable future.

The Act does not define the term “foreseeable future,” which appears in the statutory definition of “threatened species.” Our implementing regulations at 50 CFR 424.11(d) set forth a framework for evaluating the foreseeable future on a case-by-case basis. The term “foreseeable future” extends only so far into the future as the Services can reasonably determine that both the future threats and the species' responses to those threats are likely. In other words, the foreseeable future is the period of time in which we can make reliable predictions. “Reliable” does not mean “certain”; it means sufficient to provide a reasonable degree of confidence in the prediction. Thus, a prediction is reliable if it is reasonable to depend on it when making decisions.

It is not always possible or necessary to define foreseeable future as a particular number of years. Analysis of the foreseeable future uses the best scientific and commercial data available and should consider the timeframes applicable to the relevant threats and to the species' likely responses to those threats in view of its life-history characteristics. Data that are typically relevant to assessing the species' biological response include species-specific factors such as lifespan, reproductive rates or productivity, certain behaviors, and other demographic factors.

Analytical Framework

The SSA report documents the results of our comprehensive biological status review for the species, including an assessment of the potential threats to the species. The SSA report does not represent a decision by the Service on whether the species should be proposed for listing as an endangered or threatened species under the Act. It does, however, provide the scientific basis that informs our regulatory decisions, which involve the further application of standards within the Act and its implementing regulations and policies. The following sections provide summaries of the key results and conclusions from the SSA report; the full SSA report can be found on the Mountain-Prairie Region website at
https://www.fws.gov/mountain-prairie/
and at
http://www.regulations.gov
under Docket No. FWS-R6-ES-2016-0106.

To assess wolverine viability, we used the three conservation biology principles of resiliency, redundancy, and representation (Shaffer and Stein 2000, pp. 306-310). Briefly, resiliency supports the ability of the species to withstand environmental and demographic stochasticity (for example, wet or dry, warm or cold years), redundancy supports the ability of the species to withstand catastrophic events (for example, droughts, large pollution events), and representation supports the ability of the species to adapt over time to long-term changes in the environment (for example, climate changes). In general, the more resilient and redundant a species is and the more representation it has, the more likely it is to sustain populations over time, even under changing environmental conditions. Using these principles, we identified the species' ecological requirements for survival and reproduction at the individual, population, and species levels, and described the beneficial and risk factors influencing the species' viability.

The SSA process can be categorized into three sequential stages. During the first stage, we evaluated the individual species' life-history needs. The next stage involved an assessment of the historical and current condition of the species' demographics and habitat characteristics, including an explanation of how the species arrived at its current condition. The final stage of the SSA involved making predictions about the species' responses to positive and negative environmental and anthropogenic influences. This process used the best available information to characterize viability as the ability of a species to sustain populations in the wild over time. We use this information to inform our regulatory decision.

Distinct Population Segment

Pursuant to the Act, we must consider for listing any species, subspecies, or, for vertebrates, any distinct population segment (DPS) of these taxa, if there is sufficient information to indicate that such action may be warranted. To interpret and implement the DPS provision of the Act and Congressional guidance, the Service and the National Marine Fisheries Service published, on February 7, 1996, an interagency Policy

Regarding the Recognition of Distinct Vertebrate Population Segments under the Act (61 FR 4722; February 7, 1996). This policy addresses the recognition of DPSs for potential listing actions. The policy allows for more refined application of the Act that better reflects the biological needs of the taxon being considered, and avoids the inclusion of entities that do not require its protective measures.

Under our DPS policy, three elements are considered in a decision regarding the status of a possible DPS as endangered or threatened under the Act. These are applied similarly for additions to the list of endangered and threatened species, reclassification, and removal from the list. They are: (1) Discreteness of the population segment in relation to the remainder of the taxon; (2) the biological or ecological significance of the population segment to the taxon to which it belongs; and (3) the population segment's conservation status in relation to the Act's standards for listing (
i.e.,
whether the population segment is, when treated as if it were a species or subspecies, an endangered or threatened species). Discreteness refers to the degree of isolation of a population from other members of the species, and we evaluate this factor based on specific criteria. If a population segment is considered discrete, we must consider whether the discrete segment is “significant” to the taxon to which it belongs by using the best available scientific and commercial information. When determining if a potential DPS is significant, our policy directs us to sparingly list DPSs while encouraging the conservation of genetic diversity. If we determine that a population segment is both discrete and significant, we then evaluate it for endangered or threatened species status based on the Act's standards.

Both new and updated information and analyses presented in the wolverine SSA report, summarized below in support of our listing determination, along with public comment, have prompted us to reevaluate our previous assessment of the DPS (presented in our 2013 proposed listing rule, which in turn relied on the DPS analysis completed in our 2010 12-month finding) with respect to wolverine in the contiguous United States. Below we provide our revised evaluation of discreteness under the DPS policy of the segment of the North American wolverine occurring in the contiguous United States.

Distinct Population Segment Analysis for Wolverine in the Contiguous United States

Analysis of Discreteness

Under our DPS Policy, a population segment of a vertebrate species may be considered discrete if it satisfies either one of the following conditions: (1) It is markedly separated from other populations of the same taxon as a consequence of physical, physiological, ecological, or behavioral factors (quantitative measures of genetic or morphological discontinuity may provide evidence of this separation); or (2) it is delimited by international governmental boundaries within which differences in control of exploitation, management of habitat, conservation status, or regulatory mechanisms exist that are significant in light of section 4(a)(1)(D) of the Act (inadequacy of existing regulatory mechanisms).
Discreteness Based on Marked Separation

In our February 4, 2013, proposed listing rule (78 FR 7864), we did not rely on marked separation from other populations to support discreteness of the contiguous United States wolverine population. As supported by information in the SSA report, we maintain that there are no physical, physiological, ecological, or behavioral factors separating wolverines in the contiguous United States from wolverines in Canada. We do not consider wolverines in the contiguous United States to be genetically isolated from wolverines in Canada (McKelvey
et al.
2014; Pilgrim and Schwartz 2018). Therefore, wolverines in the contiguous United States are not discrete based on marked separation from other populations of the same taxon.

Discreteness Based on the International Border—Legal Status Conveyed by National, State, and Provincial Governments; Differences in Control of Exploitation

Our 2013 proposed rule (78 FR 7864), which incorporated by reference our DPS analysis from our 2010 12-month finding, found there was no significant difference between the legal status of wolverines between Canada and the United States (75 FR 78030; December 14, 2010). In the wolverine SSA report, we provide an updated assessment of legal protections and regulatory mechanisms for wolverine in North America (Service 2018, pp. 70-71, Appendix G). Legal protections in the contiguous United States include State listing in California and Oregon (threatened), endangered in Colorado, a candidate species in Washington, non-game species protections in Idaho and Wyoming, a species of concern and furbearer with a closed season in Montana, and protected from collection, importation, and possession in Utah. In Canada, provincial designations range from endangered to threatened in eastern provinces, and sensitive/special concern to no ranking in other provinces (definitions provided by the Committee on the Status of Endangered Wildlife in Canada, 2014). As was determined in our 2013 proposed listing rule (78 FR 7864), we again find no significant differences in legal status.

In the 2010 12-month finding (75 FR 78030) and reiterated in our 2013 proposed listing rule (78 FR 7864), we stated that differences in control of exploitation exist, but favor the contiguous United States population. Trapping or hunting of wolverines is currently prohibited in the contiguous United States and regulated as appropriate in Canada (Service 2018, pp. 68-69). In the wolverine SSA report, we included a new analysis of trapping in southern Canada and trapping effort along the U.S.-Canada border, which we found to be limited. Thus, we conclude that the differences in exploitation are not significant in light of section 4(a)(1)(D) of the Act (inadequacy of existing regulatory mechanisms).

Discreteness Based on the International Border—Differences in Management of Habitat

As we outlined in the proposed 4(d) rule (78 FR 7888) management activities (
e.g.,
timber harvest, wildland firefighting, prescribed fire, and silviculture) can modify wolverine habitat, but this generalist species appears to be little affected by changes to the vegetative characteristics of its habitat. In addition, most wolverine habitat occurs at high elevations in rugged terrain that is not conducive to intensive forms of silviculture and timber harvest. Habitat management is not a conservation need for wolverine. Therefore, differences in management of habitat between the United States and Canada are not significant in light of section 4(a)(1)(D) of the Act.

Discreteness Based on the International Border—Differences in Conservation Status

In the December 14, 2010, 12-month finding (75 FR 78030), which is incorporated and discussed in the February 4, 2013, proposed listing rule (78 FR 7864), we found that the wolverine population in the contiguous United States met the second DPS discreteness condition because of

differences in conservation status as delimited by the U.S.-Canada international governmental boundary. We found that those differences were substantial and significant in light of section 4(a)(1)(D) of the Act. We stated that in the remaining current range in Canada and Alaska, wolverines exist in well-distributed, interconnected, large populations. We added that, conversely, wolverine populations in the remaining United States range appear to be at numbers so low that their continued existence could be at risk, especially in light of the threats to the species. In the 2010 finding, we stated that risks come from three main factors: (1) Small total population size; (2) effective population size below that needed to maintain genetic diversity and demographic stability; and (3) the fragmented nature of wolverine habitat in the contiguous United States that results in smaller, isolated sky island patches separated by unsuitable habitat. We stated it was apparent that maintaining wolverines within their native range in the contiguous United States into the future is likely to require regulatory mechanisms that are not currently in place. As a result, we concluded that the contiguous United States population of the wolverine meets the discreteness criterion in our DPS Policy (61 FR 4722, February 7, 1996). Consequently, we used the international border between the United States and Canada to define the northern boundary of the contiguous United States wolverine DPS in our December 14, 2010, 12-month finding (75 FR 78030) and our February 4, 2013, proposed listing rule (78 FR 7864). Below we provide a reevaluation of that determination supported by information presented in the wolverine SSA report.

Small Total Population Size—
Wolverine densities vary across North America and have been described as naturally low (van Zyll de Jong 1975, p. 434); wolverine populations are naturally uncommon given the species' large home range, wide-ranging movements, and solitary characteristics (Service 2018, p. 56). There are many fewer wolverines in the contiguous United States than there are in Canada and Alaska (Committee on the Status of Endangered Wildlife in Canada (COSEWIC) 2014, p. 36; Inman
et al.
2013, p. 282; Service 2018, p. 71), but this is more a reflection of the amount of suitable habitat available within the contiguous United States (both currently and historically) for a species that needs large exclusive territories, than it is a reflection of poor conservation status. Wolverines in Canada are considered to occur as a single large group as they are easily able to move between areas of suitable habitat and because wolverine habitat is relatively contiguous (Harrower 2017, pers. comm.). However, wolverines in the contiguous United States are considered to be a metapopulation connected with wolverine populations in Canada (Inman
et al.
2013, p. 277). Wolverines currently occupy areas in the contiguous United States where they were once extirpated and continue to repopulate the contiguous United States after decades of unregulated trapping, hunting, and poisoning (Service 2018, p. iv). The same holds true for Canada, where wolverines are being detected in areas once extirpated (COSEWIC 2014, p. v).

These movement patterns are supported by recent genetic information that indicates wolverines from Canada have slowly repopulated the contiguous United States over the past century since the era of unregulated persecution (Service 2018, pp. 45-50). This point is discussed in detail below in the
Genetic Diversity
section of this withdrawal. We stated in the December 14, 2010, finding that differences in population sizes between the contiguous United States and Canada were reflective of a difference in conservation status (75 FR 78030). However, based on new information, we now conclude that the contiguous United States wolverines represent a peripheral population at the southern extent of the North American wolverine range. Thus, we now consider the small population size of wolverines in the United States to be a natural result of habitat fragmentation and not reflective of a difference in conservation status (see
Habitat Fragmentation
below for more detail). Therefore, any difference in population size on the contiguous United States side of the international border is not a significant difference in conservation status in light of section 4(a)(1)(D) of the Act as it applies to discreteness.

Effective Population Size
—Effective population size (
N
e
) is defined as “the size of an idealized population that would experience the same amount of genetic drift and inbreeding as the population of interest (Service 2018, Box 2). In popular terms,
N
e
is the number of individuals in a population that contribute offspring to the next generation” (Hoffman
et al.
2017, p. 507). Effective population size can be interpreted differently depending on how it's defined and used, and the concept of effective population size (
N
e
) (see review by Wang
et al.
2016) and, relatedly, minimum viable population, has been a topic of debate, particularly the 50/500 rule (population size of 50 for short-term, and 500 for long-term genetic health). Importantly, the concept and guidelines for genetically effective population size were developed for a single, isolated population (Laikre
et al.
2016, p. 280). The term “effective population size” is not a meaningful term unless additional context is provided relative to which concept of population size is being evaluated (Ewens 1990, p. 309). Demographic factors are needed when interpreting actual population size from an effective population size; thus, there is no justification for a fixed, genetically derived minimum viable population size value of `500' as each case is unique and is dependent on such factors as sex ratio, subpopulations, dispersal, and immigration (Ewens 1990, pp. 311-313).

As noted above, we do not consider the wolverine population in the contiguous United States to be genetically isolated from wolverines on the other side of the international border in Canada. In the wolverine SSA report, we provide a contextual discussion of the effective population size concept, particularly in the context of genetic studies related to the phylogeographic history of the North American wolverine (Service 2018, pp. 45-50), which was not well described in the 2013 proposed rule. In sum, the spatial distribution of genetic variability currently observed in wolverines in North America appears to be a reflection of a complex history in which population abundance has fluctuated since the time of the last glaciation with insufficient time passing since human persecution, since at least the 1700s, to allow for full recovery of wolverine densities (Cardinal 2004, pp. 23-24; Zigouris
et al.
2012, p. 1,554). This history and the fact that wolverines in the contiguous United States occupy the southern periphery of its entire North American range are important considerations. The wolverine SSA report also presents information from genetic and observational studies that provide support for wolverine movement across the international border of the contiguous United States and Canada (Aubry
et al.
2016, pp. 16, 20; Lucid
et al.
2016, p. 184; Service 2018, pp. 9-23). Thus, we consider wolverines that occupy the contiguous United States to be genetically continuous with wolverines in adjacent Canadian provinces.

Wolverines travel (disperse) through areas outside high-elevation, forested habitats. For example, tracked movements of a male wolverine, M56, from Wyoming into Colorado and its subsequent discovery in North Dakota, indicate extensive travel outside of

modeled primary wolverine habitat (
i.e.,
Inman
et al.
2013), including through arid grasslands and shrubland habitats of the Wyoming Basin ecoregion (Packila
et al.
2017, entire). This animal's movement also supports some level of connectivity (and potential gene flow) between currently occupied habitat (Wyoming) and unoccupied habitat within the wolverine's historical range (Colorado) (Packila
et al.
2017, p. 404). Similarly wolverines in the North Cascades region have moved from Washington and Idaho into British Columbia, and from Montana to British Columbia and Alberta (Service 2018, p. 45). Based on genetic analyses, the male wolverine currently occupying an area within the Sierra Nevada Mountains of California also represents evidence of connectivity between wolverine populations of the Rocky and Sierra Nevada Mountain Ranges (Moriarty
et al.
2009, p. 154). Within the Southwestern Crown of the Continent (SWCC) in northwestern Montana, cross-valley movements of wolverines have been detected, which researchers believe is an indication of good connectivity in this region (SWCC Working Group 2016, pers. comm.).

A preliminary mitochondrial DNA analysis was prepared for wolverine samples collected during the winters of 2015-2016 and 2016-2017 as part of the Western States Wolverine Conservation Project—Coordinated Occupancy Survey (Pilgrim and Schwartz 2018, entire). All 45 wolverines identified from samples collected in Idaho, Montana, and Wyoming match haplotype Wilson-A, which is common throughout the Rocky Mountains, Alaska, and Canada, while all 5 wolverines identified from samples collected in Washington match haplotype Wilson-C (Pilgrim and Schwartz 2018, p. 3). Previous analyses of recent or modern (1989-2012) samples from the Cascades Range in northern Washington and southern British Columbia, as presented in McKelvey
et al.
(2014, p. 328), were characterized as haplotype C, and one historical (defined in this study as pre-1930) sample as haplotype A (McKelvey
et al.
2014, p. 327). Outside of this region, haplotype C has been found only in Alberta, Saskatchewan, and Nunavut provinces (McKelvey
et al.
2014, p. 330). Based on mitochondrial DNA, McKelvey
et al.
(2014, p. 330) concluded that modern (defined in their study as 1989-2012) wolverine populations in the contiguous United States are the result of recolonization (following persecution during a period of unregulated hunting or trapping and poisoning) from the north. The additional mitochondrial analysis from samples collected in 2015, 2016, and 2017 provides further support that all contiguous United States historical (pre-1900) and recent wolverine populations are likely descendants of immigrants from Canada.

The 2013 proposed rule presented an effective population size estimate for wolverines in the contiguous United States from a publication by Schwartz
et al.
(2009), which estimated a summed effective population size of 35, with credible limits from 28 to 52 (Schwartz
et al.
2009, p. 3,226). As described in the wolverine SSA report, the study used wolverine samples from the main part of the Rocky Mountain wolverine populations and did not include subpopulations from two other mountain regions in Montana, and samples were missing from other parts of the wolverine range in Idaho and other areas of Montana. Thus, the analysis missed wolverine subpopulations and individuals, which would underestimate the results for this type of analysis. Furthermore, a small effective population size would be more of a concern if the population was in isolation; however, wolverines in the contiguous United States are not genetically or physically isolated from wolverines in Canada.

To summarize, the currently known spatial distribution of genetic variability in wolverines in North America appears to be a reflection of a complex history where population abundance has fluctuated since the time of the last glaciation and insufficient time has passed since human persecution for a full recovery of wolverine densities (Cardinal 2004, pp. 23-24; Zigouris
et al.
2012, p. 1,554). Zigouris
et al.
(2012, p. 1,545) noted that the genetic diversity reported in Cegelski
et al.
(2006) and Kyle and Strobeck (2001, 2002) for the southwestern edge of the North American range represented only part of the diversity in the northern populations of wolverines. Zigouris
et al.
(2012, p. 1,545) posit that the irregular distribution of wolverines in the southwestern periphery and the genetic diversity observed in those analyses is a result of population bottlenecks that were caused by range contractions from a panmictic (random mating) northern core population approximately 150 years ago coinciding with human persecution. Recent dispersals of wolverines into Colorado (2009), California (2008), and Utah (2014) provide evidence for connectivity and the potential for gene flow between Northern Rocky Mountain populations and areas where wolverines were extirpated. As noted above, there is also recent evidence of wolverine movement across the international border. Furthermore, our analysis of trapping levels in the wolverine SSA report does not support previous assumptions that trapping in Canada near the border acts as a barrier to wolverine movement into the contiguous United States (Service 2018, pp. 68-69). Finally, very few successful migrants are needed per generation to maintain at least 95 percent of the genetic variation in the next 100 generations (approximately 750 years) in the contiguous United States (Cegelski
et al.
2006, p. 209).

We conclude that this level of migration from the north has already been occurring following the end of intense persecution of this species; wolverines are currently observed in previously occupied areas within the contiguous United States. Given the recent observations of wolverines moving vast distances over varied terrain and across the U.S.-Canada border, our recent assessment of the low levels of trapping mortality in Canada near the border, and further confirmation of Canada as the source of wolverine genetics present in contiguous United States wolverines, we believe that wolverines in the contiguous United States are not separated genetically from the larger population in Canada. Wolverines in the contiguous United States exhibit genetic and phenotypic similarities with wolverines in Canada that implies connectivity with Canada. As such, we conclude that it is not biologically appropriate to consider the low effective population size of wolverines on the contiguous United States side of the border as a difference in conservation status that is significant in light of section 4(a)(1)(D) of the Act as it applies to discreteness. For additional information related to wolverine genetic diversity and effective population size, see
Genetic Diversity
below and the wolverine SSA report (Service 2018, pp. 45-50).

Habitat Fragmentation
—In our 2010 12-month finding (incorporated into the 2013 proposed listing rule), we stated that wolverine habitat in the contiguous United States consists of small, isolated islands of high-elevation habitat separated from each other by low valleys of unsuitable habitat. We also described that these `habitat islands' are represented by areas containing spring snow, citing Copeland
et al.
(2010). We concluded that the fragmented nature and distribution of wolverine habitat in the contiguous United States results in a population that is highly vulnerable to extirpation because of lack of

connectivity between subpopulations, and this also makes them more vulnerable to external threats (75 FR 78030; December 14, 2010).

Our previous analysis of wolverine habitat fragmentation relied upon the assumption that wolverines are constricted to habitats that contain deep, persistent spring snow cover and, therefore, are more or less confined to areas that were defined by the Copeland
et al.
(2010) spring snow cover model. However, wolverines are observed in and move through areas without snow cover (
e.g.,
male wolverines dispersing to California and Colorado), and female wolverines have successfully denned in areas outside previously modeled projections of deep, persistent spring snow cover (
e.g.,
Webb
et al.
2016; Persson 2017, pers. comm.; Jokinen 2018, pers. comm.).

We now conclude that it is not accurate to categorize the occupied habitat of wolverines in the contiguous United States as `habitat islands.' As discussed above, wolverine populations in the contiguous United States represent the southern periphery of a much larger range of the North American wolverine due to naturally occurring landscape features such as high elevation and topographic roughness of mountain regions. Thus, the distribution of persistent spring snow cover in mountainous regions does not represent the only determining habitat feature for wolverines. The availability of prey and avoidance of predators are also important elements of wolverine habitat (Inman
et al.
2012, p. 785; Scrafford
et al.
2017, p. 34)). As described in the SSA report, wolverines use a unique and productive ecological niche that allows them to occupy high-elevation regions across the northwestern portion of the contiguous United States (Service 2018, pp. 27, 38). Finally, as noted above, wolverine movement in the contiguous United States is not constrained by high-elevation habitat or snow cover, and wolverines can easily move and disperse long distances in the western United States (
e.g.,
SWCC Working Group 2016, pers. comm.; Packila
et al.
2017, entire). Therefore, habitat fragmentation in the context of availability of persistent spring snow cover or loss of connectivity in the contiguous United States is not an appropriate difference in conservation status in light of section 4(a)(1)(D) of the Act as it applies to discreteness.

Discreteness Based on the International Border—Differences in Regulatory Mechanisms

Because there aren't significant differences in control of exploitation, legal conservation status, and management of habitat, nor other threats to the wolverine requiring regulatory mechanisms to address them, we conclude that there are not differences in regulatory mechanisms between the United States and Canada that are significant in light of section 4(a)(1)(D).

Conclusion on Discreteness

Based on our updated analysis described above and supported by information in the wolverine SSA report, the contiguous United States population of wolverine does not meet the discreteness criterion in our DPS Policy (61 FR 4722; February 7, 1996). As a result, the contiguous United States population of wolverines does not qualify as a DPS and is not a listable entity under section 3(16) of the Act. After determining that a vertebrate population is not discrete, we are not required to complete an analysis to determine if the population in question is significant according to our DPS Policy.

DPS Conclusion

Based on the best available information, we conclude that the population of wolverines in the contiguous United States is not discrete in relation to the remainder of the species in North America. As a result, the population of wolverines in the contiguous United States is not a listable entity under section 3(16) of the Act.

The DPS Policy sets forth a three-step process for determining whether a vertebrate population as a separate entity warrants listing: (1) Determine whether the population is discrete; (2) if the population is discrete, determine whether the population is significant to the taxon as a whole; and (3) if the population is both discrete and significant, then evaluate the conservation status of the population to determine whether it is endangered or threatened. Although we have determined that wolverines in the contiguous United States do not qualify as a DPS and, therefore, are not a listable entity, we provide below a status determination of the wolverine population in the contiguous United States. The DPS Policy neither requires nor prohibits completion of a status determination once we have determined that a population does not qualify as a DPS. Nevertheless, in this instance, we concluded that completing an assessment—and detailing the nature, scope, and likely effect of the threats to the population and the species—would provide us and the public with useful information regarding wolverines occupying the contiguous United States.

Summary of Biological Status and Threats

In preparing the SSA report for the wolverine, we reviewed available reports and peer-reviewed literature, incorporated survey information, and contacted species experts to collect additional unpublished information for the North American subspecies (
Gulo gulo luscus),
including Canada and Alaska. We identified uncertainties and data gaps in our assessment of the current and future status of the species. We also evaluated the appropriate analytical tools to address these gaps and conducted discussions with species experts and prepared updated maps of the known species' range in North America. In some instances, we used publications and other reports (primarily from Fenno-Scandinavia) of the Eurasian subspecies (
G. g. gulo
) in completing this assessment.

Since the publication of the February 4, 2013, proposed listing rule (78 FR 7864), several new wolverine studies have been published (
e.g.,
Aronsson 2017, Aronsson and Persson 2016, Aronsson
et al.
2017, Heinemeyer
et al.
2019, Jokinen et al, 2019, Magoun
et al.
2017, Persson
et al.
2017, Stewart
et al.
2016, Webb
et al.
2016, see additional list of citations in the wolverine SSA report), which have added to our understanding of wolverine biology while also highlighting new insights into identifying key species' needs and their interactions with both abiotic and biotic factors. This new information is particularly relevant for a difficult-to-study animal like the wolverine.

Using the species, individual, and population needs identified for the wolverine and location results from surveys and studies, we conducted a geospatial analysis to estimate the current potential extent of occurrence for the North American wolverine in North America including the contiguous United States (Figure 1; Service 2018). “Current potential extent” represents the perimeter of the outermost geographic limits based on all (available) occurrence records (that is, the maximum extent of occurrences) of a species minus those areas where we believe the species has been extirpated (Service 2017). We then evaluated this area and previous estimates of potentially suitable habitat in the western-northwestern United States to

assess the species' current conditions within that region. Our future-condition analysis includes the potential conditions that the species or its habitat may face, that is, the most probable scenario if those conditions are realized in the future. This most probable scenario includes consideration of the sources that have the potential to most likely impact the species at the population or rangewide scales in the future, including potential cumulative impacts.

BILLING CODE 4333-15-P

EP13OC20.000

BILLING CODE 4333-15-C

Our analysis of potential future effects to the North American wolverine and its habitat that are associated with climate change (probabilistic estimates for temperature and precipitation) is presented in the SSA report and summarized here. This analysis was based on downscaled (high resolution local climate information derived from global climate models) climate model projections, including a detailed study of two regions in the western United States—Glacier National Park (currently occupied by reproducing wolverines) and Rocky Mountain National Park (occupied by a single male wolverine from 2009 to at least 2012, but not known to be currently occupied). The two regions studied include a high-latitude area near tree line within Glacier National Park, where tree line occurs at ~ 1,800 to 2,100 m (5,906 to 6,890 ft) that is currently occupied by wolverines; and a lower latitude area within Rocky Mountain National Park, where tree line occurs at higher elevation (~ 3,500 m (11,483 ft)) (Ray
et al.
2017, p. 2). These sites were selected to bracket the range of latitude and elevation wolverines currently occupy in the contiguous United States (Ray
et al.
2017, p. 2).

For the purpose of this assessment, we generally define viability as “consisting of self-sustaining populations that are well distributed throughout the species' range,” and where “[s]elf-sustaining populations are those that are sufficiently abundant and have sufficient genetic diversity to display the array of life history strategies and forms that will provide for their persistence and adaptability in the planning area over time” (Committee of Scientists 1999, p. 38). We use a timeframe of approximately 38 to 50 years for assessing future effects to wolverine viability. This timeframe captures consideration of the projected future conditions related to trapping/harvesting, climate change, or other potential cumulative impacts (Service 2018, p. 73). Beyond this range, climate

modeling uncertainty increases substantially. We believe this is a reasonable timeframe to consider as it includes the potential for observing these effects over several generations of the wolverine.

As discussed above in
Analytical Framework,
we consider what the species needs to maintain viability by characterizing the status of the species in terms of resiliency, redundancy, and representation (Wolf
et al.
2015, entire). Resiliency is having sufficiently large populations for the species to withstand stochastic events (arising from random factors). We can measure resiliency based on metrics of population health; for example, birth versus death rates and population size. Resilient populations are better able to withstand disturbances such as random fluctuations in birth rates (demographic stochasticity), variations in rainfall (environmental stochasticity), or the effects of anthropogenic activities.

Redundancy is having a sufficient number of populations for the species to withstand catastrophic events (such as a rare destructive natural event or episode involving many populations). Redundancy is about spreading the risk and can be measured through the duplication and distribution of populations across the range of the species. The greater the number of populations a species has distributed over a larger landscape, the better it can withstand catastrophic events.

Representation is having the breadth of genetic makeup of the species to adapt to changing environmental conditions. Representation can be measured through the genetic diversity within and among populations and the ecological diversity (also called environmental variation or diversity) of populations across the species' range. The more representation, or diversity, a species has, the more it is capable of adapting to changes (natural or human caused) in its environment. In the absence of species-specific genetic and ecological diversity information, we evaluate representation based on the extent and variability of habitat characteristics within the geographical range.

Life-History Needs

Wolverines are capable of moving and dispersing over great distances over short periods of time. Wolverine populations are characterized by naturally low densities in North America. The species is highly territorial, with very little overlap between same-sex adults. Wolverines occupy a variety of habitats, but generally select habitat in locations away from human settlements. Wolverines consume a variety of food resources, and seasonal switching of prey is commonly observed. As with other Arctic mammals, wolverines have the ability to adapt to both warm and cold ambient temperatures and solar radiation through both physiological and behavioral responses, such as vasodilation, increase in skin temperature, seasonal adjustments in fur insulation, and micro- and macro-habitat selection.

Wolverine reproduction includes the following characteristics: polygamous behavior (
i.e.,
male mates with more than one female each year), delayed implantation (up to 6 months), a short gestation period (30-40 days), denning behavior, and an extended period of maternal care. The reproductive behavior in wolverines is temporally adapted to take advantage of the availability of food resources, limited interspecific competition, and snow cover in the winter.

Since the publication of the Service's 2013 proposed rule to list the distinct population segment of the North American wolverine in the contiguous United States (78 FR 7864; February 4, 2013), several new wolverine studies have been published (
e.g.,
Aronsson 2017, Aronsson and Persson 2016, Aronsson
et al.
2017, Heinemeyer
et al.
2019, Jokinen et al, 2019, Magoun
et al.
2017, Persson
et al.
2017, Stewart
et al.
2016, Webb
et al.
2016, see additional list of citations in the wolverine SSA report). These studies have improved our understanding of wolverine biology while also highlighting new insights into identifying key species' needs and their interactions with both abiotic and biotic factors. Of particular importance relative to life history needs and wolverine reproductive behavior, wolverine populations and wolverine dens have been observed outside previously modeled projections of spring snow cover.

Overall, the best available information indicates that within the contiguous United States the wolverine's physical and ecological needs include:

(1) Large territories in relatively inaccessible landscapes, at high elevation (1,800 to 3,500 m (5,906 to 11,483 ft));

(2) access to a variety of food resources, which vary with seasons; and

(3) physical/structural features (
e.g.,
talus slopes, rugged terrain) linked to reproductive behavioral patterns.

Current Condition

Current Potential Extent of Occurrence

As noted above, using the best available information on current distribution and recent occurrences, we created maps to describe an area of “current potential extent of occurrence” (current potential extent) of wolverine for the western-northwestern contiguous United States (Service 2018, pp. 12-13, 15). The current potential extent represents the perimeter of the outermost geographic limits based on all (available) occurrence records (that is, the maximum extent of occurrences) for the wolverine minus those areas where we believe the species has been extirpated (Service 2018, pp. 11-12). The current potential extent area identified in Figure 2 encompasses approximately 280,316 km
2
(69,267,592 acres (ac)) (Service 2018, p. 12). We also prepared a current potential extent map for all of North America, including Canada and Alaska, for a total estimated current potential extent of 8,114,878 km
2
(2,005,230,024 ac) (Service 2018, p. 12 and Figure 1 of this document). The current potential extent area in the contiguous United States represents approximately 3.5 percent of the total current potential extent of wolverines in North America (Service 2018, p. 13 and Figure 2 of this document).

BILLING CODE 4333-15-P

EP13OC20.001

BILLING CODE 4333-15-C
Population Abundance and Density

Areas in the western contiguous United States have been previously identified as suitable for wolverine survival (long-term survival; used by resident adults) or primary habitat, reproduction (used by reproductive females), and dispersal (female and male) of wolverines (see methodology in Inman
et al.
2013, pp. 279-280). From these results, the researchers estimated potential and current distribution and abundance of wolverines in the western contiguous United States. They estimated current population size of wolverines to be 318 individuals (range 249-626) located within the Northern Continental Divide (Montana) and areas within the following ecoregions: Salmon-Selway (Idaho, portion of eastern Oregon), Central Linkage (primarily Idaho, Montana), Greater Yellowstone (Montana, Idaho, Wyoming), and Northern Cascades (Washington) (Inman
et al.
2013, p. 282). Potential wolverine population capacity based on habitat modeling was estimated to be 644 individuals (range: 506-1,881) (Inman
et al.
2013, p. 282); however, we do not have information indicating wolverine abundance in the contiguous United States.

In the wolverine SSA report, we provide a discussion of recent studies of wolverine detections and observations in the western United States (Service 2018, pp. 51-56); however, no comprehensive surveys have been conducted across the entire area defined as the species' maximum extent of occurrence (Service 2018, p. 14; Figure 2) or current potential extent of occurrence (Figure 2 above) in the contiguous United States. Below we

provide a summary of recent wolverine observations and detections in the western United States.

A recent study (2007-2015) has demonstrated that the Cascades region of Washington and Canada supports a resident wolverine population (Aubry
et al.
2016, p. 40). For the first time in recent history, a breeding female wolverine was detected south of I-90 in the south Cascades of Washington, as well as her potential mate, indicating wolverines may be extending their current range in that area (Flatt 2018, p. 1). Wolverines have been detected in the Eagle Cap Wilderness Area in the Wallowa Mountains of northeastern Oregon in 2011-2012, 2016, and 2017 (Magoun
et al.
2013, p. 17; Magoun 2017, pers. comm.). In California, a single male wolverine occurs in the Truckee area as of March 2017 (Shufelberger 2017, pers. comm.).

Since 2010, survey and monitoring efforts in the Idaho Panhandle and adjoining areas of Washington, Montana, and British Columbia, Canada, have detected five individual male wolverines (Service 2018, p. 52). One male was also detected in British Columbia, north of Canadian Highway 3 (Lucid
et al.
2016, p. 184), which some consider to be a barrier to wildlife passage (IDFG 2017, pers. comm.). This male was most recently detected in Idaho, on March 6, 2013 (Lucid
et al.
2016, p. 175). One likely wolverine den was located in the Saint Joe Mountains in Idaho (Lucid
et al.
2017, p. 12).

Results from a pilot study to evaluate wolverine occupancy in Wyoming indicated at least three individual wolverines (at five stations) with at least one individual in the Gros Ventre and Wind River mountain ranges, and at least two individuals in the Southern Absaroka mountain range (Inman
et al.
2015, p. 9). Occupancy modeling estimated a probability of occupancy for sampled sites of 62.9 percent (Inman
et al.
2015, p. 8).

Building on the results of the Wyoming pilot study, the Western Association of Fish and Wildlife Agencies (WAFWA), in coordination with Tribal partners, formed a multi-State, multi-agency working group (Western States Wolverine Working Group) to design and implement the Western States Wolverine Conservation Project (WSWCP)-Coordinated Occupancy Survey. The primary objectives of the WSWCP include: (1) Implement a monitoring program to define a baseline wolverine distribution and genetic characteristics of the metapopulation across Montana, Idaho, Wyoming, and Washington; (2) model and maintain the connectivity of the wolverine metapopulation in the western United States; and (3) develop policies to address socio-political needs to assist wolverine population expansion as a conservation tool, including translocation of wolverines (IDFG 2016, pers. comm.; Montana FWP 2016, pers. comm.; WGFD 2016, pers. comm.).

The Wyoming Game and Fish Department began implementation of the survey in Wyoming in the Greater Yellowstone Ecosystem region and the Bighorn Mountains in the winter of 2015-2016 (WGFD 2016, pers. comm.). That initial survey detected at least three unique wolverines in the Wind River and southern Absaroka Mountain Ranges (WGFD 2016, pers. comm.).

The monitoring effort was expanded in the winter of 2016-2017 in four States (Washington, Idaho, Montana, and Wyoming), and our review of the results indicate that wolverines were detected in all four States (Service 2018, p. 53). From this study, a total of 43 unique individuals were identified, 20 males and 23 females (Pilgrim
et al.
2018, no page number).

We also received additional wolverine observations from State and Federal agencies in northwestern Wyoming. A wolverine was detected by camera in northern Grand Teton National Park, and a member of the public reported wolverine tracks in southwestern Grand Teton National Park while skiing, which was confirmed by a Forest Service biologist (Service 2018, p. 53). Both of these observations occurred in March 2017. South of this area in the Wyoming Range (about 4 miles east of Alpine, Wyoming), a wolverine was detected by camera in May 2017 (Service 2018, p. 53).

Wolverine densities vary across North America and have been described as naturally low and wolverine populations as naturally uncommon given the species' large home range, wide-ranging movements, and solitary characteristics (Service 2018, p. 56). In the contiguous United States, density estimates (number of wolverines per 1,000 km
2
(386 mi
2
)) ranged from 3.5 for the Greater Yellowstone region (2001-2008) (areas above 2,150 m (7,054 ft) (latitude-adjusted elevation), 4.5 for central Idaho (1992-1995), to 15.4 for northwestern Montana (1972-1977) (Service 2018, p. 57).

We note here that in our 2013 proposed listing rule for the wolverine (78 FR 7864), we discussed the occurrences of two dispersing individuals in California and Colorado (the Colorado wolverine was later killed in North Dakota). We know of one male wolverine in California that has consistently occupied an area much farther north in the Sierra Nevada Mountains, and we have no evidence of any other wolverines currently in the State. We have no recent records of wolverines in Arizona. Aubry
et al.
(2007, p. 2,150) identified the year 1860 as the most recent verifiable documentation of wolverines in northern New Mexico. We know of no wolverines currently occupying Colorado. As presented in Aubrey
et al.
(2007, p. 2,151; Figure 1), prior to 1900, the most recent verifiable record for wolverine in New Mexico was 1860 and 1887 for Nebraska; no records were found for Arizona, Texas, Oklahoma. This was also true for most midwestern and mid-Atlantic States (Aubrey
et al.,
2007, p. 2,152, Figure 1). Additionally, historical range maps shown in Seton (1909, p. 947; Map 51), Aubrey
et al.
(2007, p. 2,152; Figure 1), and the assessment and status review for the wolverine in Canada (COSEWIC 2014, p. 12; Figure 3) do not extend the distribution of wolverines into these regions.

Our updated analysis of wolverine occurrence in the contiguous Unted States is based on a more scientifically robust and spatially explicit assessment of the current areas occupied by wolverines in the contiguous United States, which was prepared based on verifiable wolverine records and comments received by reviewers of a draft of the wolverine SSA report (see the Historical Range and Distribution section of the wolverine SSA report for more on

[Text truncated at 120,000 characters. The full text is on the page linked above.]

---

Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2020-19538. Public record. Not legal advice.