Endangered and Threatened Wildlife and Plants; Threatened Species Status With Section 4(d) Rule for North American Wolverine

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R6-ES-2023-0216; FF09E21000 FXES11110900000 245]

RIN 1018-BH27

Endangered and Threatened Wildlife and Plants; Threatened Species Status With Section 4(d) Rule for North American Wolverine

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Final rule and interim rule with request for comments.

SUMMARY:

We, the U.S. Fish and Wildlife Service (Service), determine threatened species status under the Endangered Species Act of 1973 (Act), as amended, for the distinct population segment (DPS) of the North American wolverine (

Gulo gulo luscus

) occurring in the contiguous United States. This rule adds the contiguous U.S. DPS of the North American wolverine to the Federal List of Endangered and Threatened Wildlife. We are also issuing an interim rule under the authority of section 4(d) of the Act (an “interim 4(d) rule”) that provides the prohibitions, and exceptions to those prohibitions, necessary and advisable for the conservation of the contiguous U.S. DPS of the North American wolverine.

DATES:

Effective date:

This rule is effective January 2, 2024.

Comments due:

Comments on the interim 4(d) rule must be received or postmarked by January 29, 2024.

ADDRESSES:

Written comments on the interim 4(d) rule:

You may submit comments on the interim 4(d) rule by one of the following methods:

(1)

Electronically:

Go to the Federal eRulemaking Portal:

https://www.regulations.gov.

In the Search box, enter FWS-R6-ES-2023-0216, which is the docket number for this rulemaking. Then click on the Search button. On the resulting page, in the panel on the left side of the screen, under the Document Type heading, click on the Rules box to locate this document. You may submit a comment by clicking on “Comment.”

(2)

By hard copy:

U.S. mail: Public Comments Processing, Attn: FWS-R6-ES-2023-0216; U.S. Fish and Wildlife Service; MS: PRB/3W; 5275 Leesburg Pike; Falls Church, VA 22041-3803.

We will post all comments on

https://www.regulations.gov.

This generally means that we will post any personal information you provide us (see Public Comments Solicited on the Interim 4(d) Rule, below, for more information).

Availability of supporting materials:

This document is available on the internet at

https://www.regulations.gov

and at

https://ecos.fws.gov/ecp/species/5123.

Supporting materials we used in preparing this rule, including the 2018 species status assessment (SSA) report and the 2023 addendum to the SSA report, are available on the Service's website at

https://ecos.fws.gov/ecp/species/5123,

at

https://www.regulations.gov

at Docket No. FWS-R6-ES-2023-0216, or both.

FOR FURTHER INFORMATION CONTACT:

Jodi Bush, U.S. Fish and Wildlife Service, Pacific Region, 911 NE 11th Ave., Portland, OR 97232; telephone: (503) 231-6131. Individuals in the United States who are deaf, deafblind, hard of hearing, or have a speech disability may dial 711 (TTY, TDD, or TeleBraille) to access telecommunications relay services. Individuals outside the United States should use the relay services offered within their country to make international calls to the point-of-contact in the United States.

SUPPLEMENTARY INFORMATION:

Executive Summary

Final Rule To List the Contiguous U.S. DPS of the North American Wolverine

Why we need to publish a rule.

The Act (16 U.S.C. 1531

et seq.

) defines “species” as any subspecies of fish or wildlife or plants, and any distinct population segment (DPS) of any species of vertebrate fish or wildlife which interbreeds when mature. Under the Act, a species warrants listing if it meets the definition of an endangered species (in danger of extinction throughout all or a significant portion of its range) or a threatened species (likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range). If we determine that a species warrants listing, we must list the species promptly and designate the species' critical habitat to the maximum extent prudent and determinable. We have determined that the DPS of the North American wolverine occurring in the contiguous United States (the “contiguous U.S. DPS”) meets the Act's definition of a threatened species; therefore, we are listing it as such. Listing a species as an endangered or threatened species can be completed only by issuing a rule through the Administrative Procedure Act rulemaking process (5 U.S.C. 551

et seq.

).

What this document does.

This document is both (1) a final rule listing the contiguous U.S. DPS of the North American wolverine as a threatened species under the Act; and (2) an interim rule issued under the authority of section 4(d) of the Act (an “interim 4(d) rule”) providing the prohibitions, and exceptions to those prohibitions, that are necessary and advisable to provide for the conservation of the contiguous U.S. DPS of the North American wolverine.

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 contiguous U.S. DPS of the North American wolverine is a threatened species due primarily to the ongoing and increasing impacts of climate change and associated habitat degradation and fragmentation.

Section 4(a)(3) of the Act requires the Secretary of the Interior (Secretary) to designate critical habitat concurrent with listing to the maximum extent prudent and determinable. We have not yet obtained the necessary economic information needed to develop a proposed critical habitat designation for the contiguous U.S. DPS of the North American wolverine. Therefore, we find that designation of critical habitat for the DPS is currently not determinable.

Interim 4(d) Rule

The need for the regulatory action and how the action will meet that need.

Consistent with section 4(d) of the Act, this interim 4(d) rule provides measures that are tailored to our current understanding of the conservation needs of the North American wolverine.

Under section 4(d) of the Act, the Secretary of the Interior has discretion to issue such regulations as she deems necessary and advisable to provide for the conservation of the species. The Secretary also has the discretion to prohibit by regulation with respect to a threatened species, any act prohibited by section 9(a)(1) of the Act.

Summary of the major provisions of the regulatory action.

This interim 4(d) rule will provide for the conservation of the contiguous U.S. DPS of the North American wolverine by prohibiting the following activities, unless they fall

within the specific identified exceptions or are otherwise authorized or permitted: importing or exporting; take; possession and other acts with unlawfully taken specimens; delivering, receiving, carrying, transporting, or shipping in interstate or foreign commerce in the course of commercial activity; or selling or offering for sale in interstate or foreign commerce.

The interim 4(d) rule will also provide for the conservation of the species by allowing exceptions to the general prohibitions against “take” of the species in support of conservation actions and otherwise lawful activities that could take wolverines but at minimal levels not likely to have a negative impact on the species' conservation. The exceptions include take due to scientific research conducted on wolverines by a Federal or Tribal biologist in the course of their official duties, incidental take resulting from forest management activities for the purposes of reducing the risk or severity of wildfire, and incidental take resulting from legal trapping conducted consistent with State and Tribal trapping rules or guidelines that contain steps to minimize the potential for capture of wolverine.

Supporting Documents

A team prepared a species status assessment (SSA) for the North American wolverine (

Gulo gulo luscus

) (Service 2018, entire) (hereafter referred to as the wolverine SSA report). The SSA team was composed of U.S. Fish and Wildlife Service (Service) biologists, who consulted with other species experts. The wolverine SSA report represented a compilation of the best scientific and commercial data available (known at that time) concerning the status of the North American wolverine, 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.

More recently, the Service prepared an SSA addendum for the North American wolverine (

Gulo gulo luscus

) (Service 2023, entire) (hereafter referred to as the wolverine SSA report addendum). The wolverine SSA report addendum contains a synthesis of relevant new information that has become available since the 2018 wolverine SSA report. The wolverine SSA report addendum 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 addendum also underwent technical review by State, Federal, and Tribal biologists.

The wolverine SSA report, the wolverine SSA report addendum, and other materials relating to this rulemaking can be found at the Service's website at

https://ecos.fws.gov/ecp/species/5123,

and at

https://www.regulations.gov

at Docket No. FWS-R6-ES-2023-0216.

Previous Federal Actions

On February 4, 2013, we published in the

Federal Register

(78 FR 7864) a proposed rule to list the DPS of the North American wolverine occurring in the contiguous United States as a threatened species under the Act, with a proposed rule under section 4(d) of the Act that outlined the prohibitions, and exceptions to those prohibitions, necessary and advisable for the conservation of the wolverine. Please refer to that February 4, 2013, proposed rule (78 FR 7864) for a detailed description of previous Federal actions concerning the wolverine prior to 2013. We published a separate proposed rule in the

Federal Register

on February 4, 2013 (78 FR 7890), 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. 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 available climate change information used to determine the extent of threats to the contiguous U.S. DPS of the North American wolverine. Based on this substantial disagreement regarding the sufficiency or accuracy of the available data relevant to the proposed listing, on February 5, 2014, we announced in the

Federal Register

(79 FR 6874) a 6-month extension of the final determination of whether to list the contiguous U.S. DPS of North American wolverine as a threatened species under the Act. That document reopened the comment period on the February 4, 2013, proposed listing rule for an additional 90 days.

On August 13, 2014, we published in the

Federal Register

(79 FR 47522) a document withdrawing both proposed rules published on February 4, 2013: (1) the proposed rule to list the contiguous U.S. DPS of the North American wolverine as a threatened species under the Act, including the provisions proposed under section 4(d) of the Act; and (2) the proposed NEP designation under section 10(j) of the Act for the North American wolverine in the Southern Rocky Mountains of Colorado, northern New Mexico, and southern Wyoming. These withdrawals were based on our conclusion that the factors affecting the DPS as identified in the listing proposed rule were not as significant as believed at the time of that proposed rule's publication in 2013.

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 February 4, 2013, proposed rule to list the contiguous U.S. DPS of the North American wolverine. Numerous parties intervened in the litigation. These three cases were consolidated, and on April 4, 2016, the court issued a decision. The court granted plaintiffs' 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 the range policy to the wolverine. As a result of the court order, the August 13, 2014, withdrawal (79 FR 47522) of the February 4, 2013, proposed listing rule was vacated and remanded to the Service for further consideration consistent with the order.

In effect, the court's action returned the process to the proposed rule stage, and the status of the contiguous U.S. DPS of the North American 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 in the

Federal Register

(81 FR 71670) a document reopening the comment period on the February 4, 2013, proposed rule to list the DPS of the North American wolverine occurring in the contiguous United States as threatened under the Act (78 FR 7864). The October 18, 2016, publication also requested new information and announced that we were initiating 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. Both new and updated information and analyses presented in the wolverine 2018 SSA report, along with public comments, prompted us to reevaluate our previous assessment of the DPS (presented in our 2013 proposed listing rule (78 FR 7864), which in turn relied on the DPS analysis completed in our 2010 12-month finding (75 FR 78030)) with respect to the North American wolverine in the contiguous United States.

On October 13, 2020, we published in the

Federal Register

(85 FR 64618) another document withdrawing the February 4, 2013, proposed rule to list the DPS of the North American wolverine occurring in the contiguous United States as threatened under the Act. Our 2020 withdrawal decision was based on our conclusion that the factors affecting the North American wolverine occurring in the contiguous United States as identified in the 2013 proposed listing rule were not as significant as believed at the time of the proposed rule's publication in 2013. We also found that the North American wolverines occurring in the contiguous United States did not qualify as a DPS.

The Center for Biological Diversity and WildEarth Guardians filed lawsuits in the District Court for the District of Montana challenging the Service's 2020 decision to withdraw the February 4, 2013, proposal to list the contiguous U.S. DPS of the North American wolverine. The cases were consolidated, and the State of Idaho's motion to intervene was granted. On February 4, 2022, the Service filed a motion asking the court to voluntarily return (remand) the 2020 withdrawal decision to the Service to allow the Service to re-examine the decision in light of the intervening decision in

Center for Biological Diversity

v.

Haaland,

998 F.3d 1061 (9th Cir. 2021) (“Pacific Walrus Decision”) and to reevaluate the decision in light of new scientific information that had become available since the completion of the 2018 SSA. The Service also requested that the 2020 withdrawal decision remain in effect pending that reevaluation. On May 26, 2022, the court granted the Service's request for a voluntary remand of the 2020 withdrawal decision, but the court decided to vacate the withdrawal decision (

Ctr. for Biological Diversity

v.

Haaland,

No. CV 20-181-M-DWM (D. Mont. May 26, 2022)).

The court's May 26, 2022, action returned the listing process for the North American wolverine to the proposed rule stage. On November 23, 2022, the Service published in the

Federal Register

(87 FR 71557) a document soliciting new information on the North American wolverine and notifying the public that the February 4, 2013, proposed rule to list the contiguous U.S. DPS of the North American wolverine as threatened under the Act (78 FR 7864) had been reinstated. As of May 26, 2022, for purposes of consultation under section 7 of the Act, the North American wolverine was again a species proposed for listing and subject to conferencing requirements.

The Service then completed the wolverine SSA report addendum (Service 2023, entire), which contains a synthesis of all relevant new information that has become available since the 2018 wolverine SSA report to inform this final listing rule and the associated interim 4(d) rule.

Peer Review

Our assessment of the status of the North American wolverine contained in this document is supported by information in both the 2018 SSA report (Service 2018, entire) and the 2023 wolverine SSA report addendum (Service 2023, entire). In accordance with our joint policy on peer review published in the

Federal Register

on July 1, 1994 (59 FR 34270), and our August 22, 2016, memorandum updating and clarifying the role of peer review in listing actions under the Act, we solicited independent scientific review of the information contained in the 2018 wolverine SSA report. We sent the SSA report to four independent peer reviewers and received four responses; we incorporated the results of that review into the SSA report, as appropriate. More recently, we solicited independent scientific review of the 2023 wolverine SSA report addendum. We sent the wolverine SSA report addendum to six peer reviewers and received three responses; we incorporated the results of the peer review into the wolverine SSA report addendum, as appropriate. The peer reviews on the wolverine SSA report and the wolverine SSA report addendum can be found at

https://www.regulations.gov.

Summary of Changes

Since the publication of the February 4, 2013, proposed listing rule (78 FR 7864), the development of the 2018 SSA report (Service 2018, entire), and the publication of the October 13, 2020, withdrawal document (85 FR 64618), a substantial number of new studies have become available, refining our understanding of wolverine biology and threats affecting North American wolverines in the contiguous United States. We incorporated this new information into the 2023 wolverine SSA report addendum. We summarize the information most salient to our determination in this final rule below. We also discuss these changes where appropriate in the remainder of the document to provide further detail and context.

Ecological Requirements

The snow model used in the climate change analysis in the 2018 SSA report and October 13, 2020, withdrawal document (85 FR 64618) projected snow loss out to year 2050 in only two modeling domains (Glacier National Park and the central Rocky Mountains) (Service 2018, p. 88). Results indicated a decline in spring snow in these areas due to climate change was likely, but we were unable to extrapolate those projections across the remainder of the North American wolverine's breeding range in the contiguous United States. Persistent spring snow (greater than or equal to 1 meter on May 1; see

Climate Change,

below) was not identified as an ecological requirement for wolverines, and we assumed that if snow was necessary for denning, there would be enough spring snowpack in the future to fulfill denning needs.

Our updated climate analysis reported in the 2023 wolverine SSA report addendum projects snow loss out to 2100 across five modeling domains that cover a much larger extent of the breeding range in the contiguous United States when compared to the 2018 SSA report. In our 2023 wolverine SSA report addendum, we found declines in spring snow due to climate change are likely across the North American wolverine's range and predicted losses will be greater in 2100 than in 2050. In general, when compared to historical amounts of snow cover, nearly every area modeled (except for the Mid-Rockies) sees a decrease in snow cover and that decrease becomes larger over time. In the Mid-Rockies, snow cover increases in the short term, but as with the other areas, it decreases over time.

New research indicates that areas characterized by persistent spring snow are likely important for wolverine survival (

e.g.,

caching food) in addition to denning and reproduction. One new study reported wolverines cache food year-round, indicating that warmer temperatures could impact the ability of wolverines to store food resources by decreasing the shelf-life (usability) of cached food, and increasing competition from pilferers that benefit from a warmer climate (van der Veen et al. 2020, p. 1). Another study found evidence to support a functional

relationship between North American wolverines and persistent spring snow that could be explained by the distribution of food, disturbance, or mortality risk (Kortello et al. 2019, p. 8).

Connectivity With Canada

Connectivity with Canada is essential to the long-term viability of North American wolverines in the contiguous United States (Cegelski et al. 2006, p. 209). In the 2018 SSA report and October 13, 2020, withdrawal document (85 FR 64618), we assumed that wolverines could move freely between Canada and the United States (Service 2018, p. 104). We also concluded that trapping of wolverines did not represent a barrier to wolverine movement and dispersal along the international border (Service 2018, p. 69). Additionally, we concluded that major highways did not represent a barrier to wolverine movement (Service 2018, p. 60).

In the 2023 wolverine SSA report addendum, we affirm that connectivity with Canada is essential to the long-term viability of North American wolverines in the lower 48 States. However, our understanding of the ability of wolverines to move between Canada and the United States in the Rocky Mountains has changed. New research found an estimated 41 percent decline in the wolverine population from 2011-2020 in a portion (7,583,417 acres (ac) (30,689 square kilometers (km

2

))) of the southern Canadian Rockies, Purcell Mountains, and Selkirk Mountains important for wolverine connectivity with the United States; this decline could be attributed to one or more of the following causes: trapping, backcountry recreation, human development, and food availability (Barrueto et al. 2022, p. 4). In addition, new transboundary genetic research indicates the Trans-Canada Highway in southern British Columbia is impeding female dispersal from Canada to the United States, thereby limiting gene flow and the ability of dispersing wolverines to supplement the contiguous U.S. DPS (Sawaya et al. 2023, pp. 12, 17).

Genetic Diversity and Adaptive Capacity

In the October 13, 2020, withdrawal document (85 FR 64618), we found there was no available information to indicate that the current abundance of the North American wolverine across its range in the contiguous United States was at a level that was causing inbreeding depression or loss of genetic variation that would affect its ability to adapt to changing conditions.

New transboundary genetic research shows a sharp decline in genetic diversity and increasing population fragmentation at the southern extent of the North American wolverine's range in western North America (Sawaya et al. 2023, p. 17). As a result, there is potential for inbreeding given the relatively small population sizes and low levels of genetic diversity of wolverines in the contiguous United States, especially in the Cascade Mountains of Washington and southern British Columbia (Sawaya 2023, pers. comm.); however, inbreeding depression has not been observed. New analysis of the North American wolverine's adaptive capacity shows that their specialized habitat associations, low genetic diversity and population size, narrow ecological niche, low tolerance for human disturbance, and slow reproductive rate all contribute to the wolverine's relative difficulty in adapting in-place to future environmental change (Service 2023, p. 66).

Roads and Development

We analyzed the effects of roads and development (human disturbance) to North American wolverines in the 2018 SSA report (Service 2018, p. 62) and determined in our October 13, 2020, withdrawal document (85 FR 64618) that impacts to wolverines are small and narrow in scope and scale. We did not consider roads and development to be an impediment to wolverine movement and gene flow.

New habitat and landscape genetic research indicates multi-lane roads and human development in valley bottoms between core habitats may limit dispersal and population connectivity to some extent, especially for female wolverines. Connectivity among wolverine habitats appears to be particularly sensitive to housing developments (Balkenhol et al. 2020, p. 797). Also, new research indicates that human disturbance (road density) and food availability are major drivers of wolverine distribution in winter (Kortello et al. 2019, p. 1). Wolverine density and detection probability declined in areas with more human development (Barrueto et al. 2022, p. 4). Human development may also have cascading impacts of increasing competition from other mesocarnivores that are less affected by human disturbance (Frey et al. 2020, pp. 1136-1138; Chow-Fraser et al. 2022, p. 6; Milanesi et al. 2022, pp. 10-11).

Winter Recreation

In our 2018 SSA report and October 13, 2020, withdrawal document (85 FR 64618), we concluded that winter recreation is a low-level stressor for wolverines in the contiguous United States (Service 2018, p. 62). The limited research available at the time indicated some avoidance behavior exhibited by wolverines in areas with backcountry winter recreation, but not to the extent that we had concerns about population-level impacts.

In the 2023 wolverine SSA report addendum, we provide an updated assessment of the effects of winter recreation based on new studies. Research indicates winter recreation is negatively associated with North American wolverine habitat use, and that winter recreation is likely to increase and become more concentrated in the future as snow-covered areas decline due to climate change (Heinemeyer et al. 2019, p. 1). A large multi-State analysis of winter recreation impacts in the Northern Rocky Mountains was published in 2019, indicating greater concern for impacts to wolverines than we found in 2018 and showing a negative functional response to the level of recreation exposure within their home ranges (Heinemeyer et al. 2019a, pp. 13-14, 17-18). Additionally, new research found an incremental loss of wolverines in portions of central Idaho where winter recreation impacts are increasing (Mack and Hagan 2022, p. 13). Furthermore, forest roads used by snowmobilers in the Canadian Rockies were found to have a strong negative correlation with wolverine distribution (Kortello et al. 2019, p. 10). Wolverine detection probability in protected and non-protected habitat of southwestern Canada was found to be strongly and negatively correlated with nonmotorized recreation in summer and winter (Barrueto et al. 2022, p. 5).

Trapping

In our 2018 SSA and the October 13, 2020, withdrawal document (85 FR 64618), we concluded that overutilization does not currently represent a stressor to the North American wolverine in the contiguous United States at the individual, population, or species level. We also concluded that trapping in Canada has been and appears to be sustainable, and trapping or harvesting of wolverines along the contiguous U.S.-Canada border does not represent a stressor to wolverines migrating into the contiguous United States and does not represent a barrier to wolverine movement and dispersal along the international border (Service 2018, p. 71).

Legal trapping of wolverines has not occurred in the contiguous United States in the past 10 years, and lethal

incidental trapping of wolverines has been minimal (Service 2023, p. 38). We expect recent changes to wolf trapping regulations in Idaho and Montana to have little effect on wolverines at a population level, as long as trapping is done in a manner to limit wolverine bycatch (Idaho Department of Fish and Game (IDFG) 2023, in litt., p. 1; IDFG 2022, p. 40; Montana Fish, Wildlife and Parks (MFWP) 2023, in litt., p. 1; MFWP 2022, entire). Below, under

Overutilization for Commercial, Recreational, Scientific, or Educational Purposes,

we provide an assessment of incidental trapping and the measures States are taking to reduce incidental trapping of wolverines.

Recent research on wolverine trapping in Southern Canada indicates that trapping may be having more of a negative effect on wolverine populations in Canada than previously thought (Kortello et al. 2019, pp. 1, 10; Mowat et al. 2020, entire; Barrueto et al. 2020, p. 296; Barrueto et al. 2022, entire). Unsustainable trapping levels in Canada could limit dispersal of individuals into the contiguous United States, where the dispersal of wolverines from Southern Canada is vital to the genetic and demographic health of the U.S. population (Sawaya 2023, pers. comm.).

Summary of Comments and Recommendations

Comments on the 2013 Proposed Listing Rule

Upon publication of our February 4, 2013, proposed rule to list the DPS of North American wolverine occurring in the contiguous United States as a threatened species (78 FR 7864), we opened a 90-day public comment period, ending May 6, 2013. After we withdrew the proposed rule, on October 18, 2016 (81 FR 71670), we again opened a public comment period on our 2013 proposed listing rule; that comment period was open for 30 days, ending November 17, 2016. At both times, we contacted appropriate Federal and State agencies, scientific experts and organizations, Tribes, and other interested parties and invited them to comment on the 2013 proposed listing rule. Many of the comments we received from State agencies during our 2016 reopened comment period (81 FR 71670) were similar to those we received during the initial 2013 public comment period (78 FR 7864). All substantive information provided during both comment periods on our 2013 proposed listing rule has either been incorporated directly into this final determination or is addressed below.

Below, we present the comments received on the 2013 proposed listing rule and a summary of our responses as presented in the October 13, 2020, withdrawal document (85 FR 64618). We also provide updated responses to several of the comments based on new information presented in the 2023 wolverine SSA report addendum and this final rule. Comments are numbered below as they were numbered in the October 13, 2020, withdrawal document (85 FR 64618). Several of the comments and responses from the October 13, 2020, withdrawal document did not require revision, and they are incorporated here by reference; those comments with responses that remain the same are comments 6, 7, 9, 11, 13, 20, 21, 22, 23, and 24 (85 FR 64618 at 64622-64626).

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 snowpack.

Our 2020 Response Summarized:

Our climate assessment in the 2018 wolverine SSA report and October 13, 2020, withdrawal document focused on the impact of climate change to denning conditions for wolverines. We stated 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. 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 (on April 30/May 1). We referenced a climate analysis that included two regions, Glacier National Park and Rocky Mountain National Park. Details of this climate analysis are presented in Ray et al. (2017) and are summarized in the 2018 SSA report. Climate models in Ray et al. (2017) 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). Model projections from Ray et al. (2017) indicate significant areas (several hundred square kilometers (km

2

)/square miles (mi

2

) for each study area) of future snow (greater than 0.5 meters (m) (20 inches (in)) in depth) are likely 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.

Our 2023 Response:

Our assessment of climate change impacts to North American wolverines in the 2023 wolverine SSA report addendum, and applied in this final rule, evaluates the impact of climate warming and changes in snowpack on various aspects of wolverine ecology, not just denning habitat (see

Climate Change,

below). We now consider habitats characterized by the presence of persistent spring snow for survival and reproduction to be a physical and ecological requirement for wolverines in the contiguous United States (see

Life-History Needs,

below). New evidence from around the world reinforces that snow—especially persistent spring snow—is an important predictor of broad-scale wolverine distribution and density (Aubry et al. 2023, pp. 15-16; Carroll et al. 2020, p. 8; Fisher et al. 2022, p. 10; Glass et al. 2021, entire; Mowat et al. 2020, p. 220). Snow cover appears to influence wolverine dispersal and resulting genetic structure (Balkenhol et al. 2020, pp. 798-799). Warming future conditions could make caching food more difficult for wolverines year-round (Van der Veen et al. 2020, pp. 8-10). Climate change also has the potential to exacerbate the impacts of other stressors, including effects from roads, winter recreational activity, development, low genetic diversity, and small populations (see

Threats,

below). Wolverines have denned outside of spring snowpack in the boreal forests of Canada and Scandinavia; however, the importance of spring snow for denning may vary among areas depending on the abundance of alternative den site structures, competitors, and food resources (Persson et al. 2023, p. 5810). Furthermore, there is no evidence that North American wolverines have denned in areas outside of spring snowpack in their alpine habitats in the contiguous United States. In light of this, we do not expect North American wolverines to continue to have the same or better resiliency in the contiguous United States in the future when cold and snowy conditions are expected to decrease, with spring snowpack decreasing as much as 50 percent in some areas. Although we are not seeing deleterious effects of climate change on the contiguous U.S. population of North American wolverines currently, we expect future impacts at the population level. For further detail, see the discussion under

Climate Change,

below.

(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 2020 Response Summarized:

We stated that 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 that time (and still today), the only estimate of the number of wolverines that currently occupy the contiguous United States is the often-cited population estimate of 318 wolverines (range: 249-926) in the contiguous United States. This estimate was derived from habitat modeling presented in Inman et al. (2013). That publication also provided a modeled estimate of potential wolverine capacity in the contiguous United States of 644 wolverines (range: 506-1881). We also reported the preliminary results from the Western States Wolverine Conservation Project (WSWCP) occupancy study in four western States (Idaho, Montana, Washington, and Wyoming) and from a pilot occupancy study in Wyoming (2015-2016) (Service 2018, appendix B). Preliminary analysis of the study results indicated an average estimated probability of occupancy of 0.42, suggesting that wolverines used nearly half of all sites during the study period (MFWP 2017, pers. comm.). Although the sum of these reports cannot confirm the previous estimate 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.

We also discussed the estimated effective population size 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). We stated that the analysis missed two wolverine subpopulations as well as individuals, which would underestimate the results for this type of analysis. We went on to discuss the apparent connectivity between wolverines in the contiguous United States and Canada, and we considered the contiguous United States to be genetically continuous with wolverines in adjacent Canadian provinces. We concluded that 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.

Our 2023 Response:

The best available estimate of effective population size for the wolverine in the Northern Rocky Mountains continues to be 35 (credible interval = 28-52) (Schwartz et al. 2009, p. 3226). We estimated the effective population size of wolverines in the North Cascades to be four (Service 2023, p. 27). Overall, the effective population size estimates of wolverines in the contiguous United States are small compared to conservation guidelines, and the contiguous U.S. DPS of North American wolverines appear to be vulnerable to inbreeding and loss of genetic diversity when considered in isolation. However, only one or two effective migrants per generation (

i.e.,

the number of migrants that reproduce at the same rate as residents) are likely needed to achieve genetic population connectivity and maintain existing levels of genetic diversity (Cegelski et al. 2006, p. 209).

At the time we published the October 13, 2020, withdrawal document (85 FR 64618), we considered the contiguous U.S. population to be genetically continuous with Canada. We now know that wolverine populations in southern British Columbia and Alberta near the transboundary interface are less genetically connected to the contiguous United States than we found in our 2018 SSA. New information has revealed that female wolverines appear to avoid crossing major roadways, including the Trans-Canada Highway (Highway 1) and the Crowsnest Highway (Highway 3) in southern British Columbia (Sawaya et al. 2023, pp. 11-14). Substantially lower mitochondrial DNA diversity in the United States, as compared to mitochondrial DNA diversity in Canada, is consistent with the nuclear DNA signals of limited contemporary female gene flow between the countries and the wolverine's relatively recent recolonization at the southern edge of their range (Sawaya et al. 2023, p. 17). See “Gene Flow Between the United States and Canada” and “Population Structure and Gene Flow Within Canada,” below, for more detail. Given the new information on limited gene flow with Canada and the potential impacts of climate change to future dispersal, the low effective population size in the contiguous U.S. population of North American wolverines is a concern to future population viability.

(3) Comment:

We received several public comments during our request for information claiming that the North American wolverine faces threats from indiscriminate trapping in the contiguous United States, or are negatively impacted by incidental trapping.

Our 2020 Response Summarized:

In our October 13, 2020, withdrawal document (85 FR 64618), we stated that trapping or hunting of wolverines was not allowed in any State within the range of the wolverine in the contiguous United States, and we presented the legal protections afforded to wolverines in each State. We summarized what we knew at the time about incidental trapping. In the wolverine SSA report, we provided 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. We noted that regulated trapping and hunting of wolverines occurs in parts of Alaska and Canada, and appears to be sustainable based on population and density estimates.

Our 2023 Response:

Legal trapping of wolverines has not occurred in the contiguous United States in the past 10 years. Wolverine trapping remains closed throughout the western United States, and wolverines have retained various protected status designations in the States within their current U.S. range (Service 2023, table 10). Therefore, legal direct trapping is no longer a stressor on wolverines in the contiguous United States. In the past 10 years, lethal incidental trapping of wolverines has been minimal (approximately 1 to 2 animals per year or fewer), primarily occurring in Idaho and Montana (see

Overutilization for Commercial, Recreational, Scientific, or Educational Purposes,

below). New information suggests that recent overharvest from trapping has occurred in southern Canada in areas that could provide dispersing individuals to the contiguous United States (Mowat et al. 2020, entire). Trapping in southern Canada appears to have had a more negative effect on wolverine populations in Canada than previously thought. Legacy effects of recent unsustainable trapping levels in a portion of the southern Rocky Mountains of Canada could limit dispersal of individuals into the contiguous United States in an area where wolverine connectivity between the United States and southern Canada is vital to the genetic and demographic health of the U.S. wolverine population. See

Overutilization for Commercial, Recreational, Scientific, or Educational Purposes

and Provisions of the Interim 4(d) Rule, below, for further details.

(4) Comment:

We received several public comments identifying potential threats to wolverines from winter recreation activities, such as snowmobiling and backcountry skiing.

Our 2020 Response Summarized:

When we published our October 13, 2020, withdrawal document (85 FR 64618), there was little information on the effect of winter recreation on wolverines. We received a final report of a multiyear study on the effects of winter recreation on wolverines (Heinemeyer et al. 2017, entire) in mid-December 2017, and the results of this study were published (Heinemeyer et al. 2019a, entire) prior to the publication of our 2020 withdrawal document. The study found that wolverines were displaced from habitat by winter recreation but 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. 2019a, p. 16). The study described habitat selection as complex for female wolverines and stated that habitat selection 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. 2019a, p. 16). This study did not assess demographic effects, fitness effects, or population-level effects of winter recreation on wolverines (Heinemeyer et al. 2019a, pp. 17, 19).

Our 2023 Response:

There are multiple recent studies that indicate wolverines are negatively affected and displaced (at least temporarily) by various types of backcountry winter recreation (Barrueto et al. 2022, entire; Heinemeyer et al. 2019a, entire; Heinemeyer et al. 2019b, entire; Kortello et al. 2019, entire; Mack and Hagen 2022, entire; Regan et al. 2020, entire). The effect of winter recreation activity (of concern due to potential impacts to denning and survival), in isolation, represents a low threat to wolverines in the contiguous United States at the population level. However, in combination with other threats, including decreased snow availability (see

Climate Change,

below) and increased overlap with winter recreationalists in the future due to climate change, winter recreation could negatively affect wolverine population resilience in the future. See

Disturbance Due to Winter Recreational Activity,

below, for further details.

(5) Comment:

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

Our 2020 Response Summarized:

Our response to this comment in our October 13, 2020, withdrawal document (85 FR 64618) focused on snow availability for denning and the wolverine's ability to cope with changing snow conditions in the denning context. We stated 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 the contiguous United States in areas where wolverines are known to den at levels that will continue to support wolverines. 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.

In our evaluation of the effects of climate change to snowpack (see Service 2018, pp. 73-99), 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. These dates are more relevant to the North America wolverine's life-history needs. We also modeled the depth of “significant” snow (0.5 m (20 in)) on these dates. We found that large areas (several hundred km

2

/mi

2

for each study area) of future snow cover (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.

Our 2023 Response:

As discussed above in our response to

(1) Comment,

the wolverine is a snow-adapted species that utilizes cold and snowy habitats for multiple aspects of its life history. To inform our assessment of the wolverine's status in the contiguous United States, we updated our previous climate change analysis, the details of which are summarized in the wolverine SSA report addendum (Service 2023, pp. 47-60). Our analysis focuses on the expected loss of snowpack out to 2100 in five modeling domains that overlap with occupied and potential wolverine habitat in the contiguous United States across latitudinal, longitudinal, and elevation gradients. The Service chose a snow depth threshold of greater than or equal to 1 m (3.3 ft) to represent significant snow cover on May 1, which provides a more conservative estimate than was used in the 2018 SSA (

i.e.,

greater than or equal to 0.5 m (20 in.) on May 1). This updated analysis shows that cold and snowy conditions at high elevations are expected to decrease, with spring snowpack at denning elevations decreasing as much as 50 percent in some areas. As a result, we expect wolverine population resiliency in the contiguous United States to decrease in the future. For more information see

Climate Change,

below.

(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 2020 Response Summarized:

We acknowledged that some members of the public supported our decision to withdraw our proposed rule to list the North American wolverine occurring in the contiguous United States as a threatened species under the Act. In the wolverine SSA report (Service 2018, appendix G), we provided 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. Trapping or hunting of wolverines was prohibited in the contiguous United States when our October 13, 2020, withdrawal document (85 FR 64618) published.

Our 2023 Response:

We appreciate the regulatory protections and management measures our State wildlife agency partners and Federal resource management agencies have enacted to conserve the North American wolverine and its habitat (Service 2018, appendix G). However, we have determined that the contiguous U.S. DPS of North American wolverine meets the Act's definition of a threatened species as described in this rule due to future threats, including the reduction in spring snowpack from climate change. This determination is not a reflection on the adequacy of State management or the capability of States to manage the species but rather an acknowledgement of the serious threat posed to the species

by climate change. Along with the listing, we are finalizing an interim 4(d) rule that will promote conservation of the contiguous U.S. DPS of North American wolverine by encouraging management of the landscape by our partners in ways that meet the conservation needs of the wolverine. The provisions of this 4(d) rule provide one of many tools we will use to promote the conservation of the contiguous U.S. DPS of North American wolverine.

(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 restricted 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 2020 Response Summarized:

We found that 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) were low based on our evaluation of the best available information at the time in relation to current and potential future conditions for the North American wolverine occurring in the contiguous United States and in the context of the attributes that affect the needs of the DPS (Service 2018, p. 103). Thus, we determined that the North American wolverine in the contiguous United States did not meet the definition of an endangered species or a threatened species under the Act.

Our 2023 Response:

Our 2018 wolverine SSA report and 2023 SSA report addendum provide a thorough assessment of the threats affecting the North American wolverine in the contiguous United States. New information related to the threats affecting the contiguous U.S. DPS of the North American wolverine have led us to a different conclusion than the one we presented in our October 13, 2020, withdrawal document (85 FR 64618). In this final rule, we examine the best available information about threats to the wolverine, including effects from roads, disturbance due to winter recreational activity, other human disturbance, effects from wildland fire, disease, predation, overutilization (trapping), genetic diversity, small population effects, and climate change, including the cumulative effects of these threats. See Summary of Biological Status and Threats, below, for a complete discussion of threats affecting the DPS. After assessing the best available information, we conclude that the contiguous U.S. DPS of the North American wolverine is not currently in danger of extinction but is likely to become in danger of extinction within the foreseeable future throughout all of its range.

(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 2020 Response Summarized:

We reevaluated wolverines occurring in the contiguous United States under our Policy Regarding the Recognition of Distinct Vertebrate Population Segments Under the Endangered Species Act (DPS policy; 61 FR 4722, February 7, 1996). See Distinct Population Segment in the October 13, 2020, withdrawal document (85 FR 64618 at 64628-64631) for more information. We provided our analysis of the status of wolverines in the contiguous United States under Determination of Species Status in the October 13, 2020, withdrawal document (85 FR 64618 at 64645-64647). The topic of denning behavior is discussed in the wolverine SSA report (see “Use of Dens and Denning Behavior” under

Reproduction and Growth

in the wolverine SSA report (Service 2018, pp. 23-28)). For our analysis of the effects of climate change to North American wolverines and denning habitat, see “Climate Change and Potential for Cumulative Effects” in the October 13, 2020, withdrawal document (85 FR 64618 at 64642-64644).

Our 2023 Response:

In this final rule, we provide our revised evaluation of discreteness and significance under our DPS policy of the segment of the North American wolverine occurring in the contiguous United States considering new information available since the publication of our October 13, 2020, withdrawal document (85 FR 64618). We also explain how new information has led us to a different determination from previous DPS analyses. The analysis contained in this rulemaking supersedes and replaces any previous DPS analysis for the segment of the North American wolverine occurring in the contiguous United States. We conclude that the population of wolverines in the contiguous United States is discrete and significant in relation to the remainder of the species in North America. For more information, see Distinct Population Segment Analysis for Wolverine in the Contiguous United States, below.

The wolverine population in the contiguous United States is expected to decrease in resiliency, redundancy, and representation in the foreseeable future. The best available information suggests that habitat loss as a result of climate change, and the resulting exacerbating effect on other stressors, are likely to decrease the viability of wolverines in the contiguous United States within this century (see “Summary of Future Condition” and Determination of North American Wolverine's Status, below). Our review of the best scientific and commercial data available indicates that the contiguous U.S. DPS of the North American wolverine meets the Act's definition of a threatened species.

We acknowledge the precise causal mechanism(s) for the apparent association of wolverine distribution with persistent spring snow are not yet clear. The association could involve the importance of snow for denning or other aspects of the species' biology and ecology. We address uncertainties under

Areas of Uncertainty for Wolverine Habitat Needs,

below. That said, we know that wolverines are a species that is adapted to, and has a strong preference for, cold and snowy conditions and that these conditions will be reduced in the future. The commenter is accurate in that climate models do not predict a complete loss of snow within the North American wolverine's range in the contiguous United States. However, we expect climate change to reduce snowpack in areas used by wolverines by as much as 50 percent in some places (see our analysis under

Climate Change,

below). We conclude increasing temperatures and decreasing snowpack have the

largest potential to influence the population viability of the contiguous U.S. DPS of the North American wolverine in the future.

Regarding winter recreation, new information supports our understanding that some forms of winter recreation, backcountry motorized recreation especially, have the potential to negatively impact wolverines. See our response to

(4) Comment,

above, and

Disturbance Due to Winter Recreational Activity,

below, for further details.

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 Act's 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 2020 Response Summarized:

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 studies of wolverines.

We used the best available scientific information to provide a detailed description of the North American wolverine's life history and ecology, including a detailed discussion of wolverine denning habitat and behavior. We conducted an analysis to assess the current population status. Conservation measures and regulatory mechanisms relative to the North American wolverine were also provided in the wolverine SSA report. This information was used to evaluate the current and future conditions of the DPS. We evaluated results from a fine-scale analysis of the potential effects of climate change to future snowpack conditions and found significant areas of snow (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 did not warrant listing as threatened or endangered under the Act in 2020.

Our 2023 Response:

We appreciate the commitment of the Tribal nations to further our knowledge of this unique species. We have gathered the best available information on North American wolverines and used this information to assess the current and future population status of wolverines in the contiguous United States.

Regarding winter recreation, see our response to

(4) Comment,

above, and

Disturbance Due to Winter Recreational Activity,

below, for further details.

Regarding the effects of climate change to North American wolverines, see our response to

(1) Comment,

above, and

Climate Change,

below. We conclude that the contiguous U.S. DPS of the North American wolverine is not currently in danger of extinction but is likely to become in danger of extinction within the foreseeable future throughout all of its range.

(15) Comment:

We received comments from one Tribe whose 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 2020 Response Summarized:

We appreciate the perspective provided regarding the importance of the North American 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. The best available scientific 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 DPS. Based on the best available information, we determined that the North American wolverine in the contiguous United States did not warrant listing as endangered or threatened under the Act in 2020.

Our 2023 Response:

Information previously provided by the Tribe was considered in the 2018 SSA report. We include new and updated scientific information in the 2023 wolverine SSA report addendum, including information on the current conditions (

i.e.,

potential stressors, including winter recreation) and future conditions (

e.g.,

effects of climate change) of the DPS. Based on the best available information, we now determine that the contiguous U.S. DPS of the North American wolverine meets the Act's definition of a threatened species.

State Agency Comments

In our October 13, 2020, withdrawal document (85 FR 64618), we also addressed the extensive comments from several western States, including previously submitted comments in response to the February 4, 2013, proposed listing rule (78 FR 7864) as well as additional comments submitted in response to our October 18, 2016, document that reopened the public comment period on the 2013 proposed listing rule (81 FR 71670). 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 February 4, 2013, proposed listing 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 February 4, 2013, proposed listing rule.

Our 2020 Response Summarized:

In preparing the 2018 SSA report for the North American wolverine, our foundational science document for informing the October 13, 2020, withdrawal (85 FR 64618), we reviewed available reports and peer-reviewed literature, incorporated survey information for the purpose of preparing updated maps of the known current and historical occurrences of the North American wolverine, 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 2018 SSA report, the draft wolverine SSA report was submitted for peer review to four independent peer reviewers and submitted to our Federal, State, and Tribal partners for scientific review. We incorporated the results of these reviews in the 2018 wolverine SSA report, as appropriate.

We recognized that climate trends and future (2055 and later) climate model projections indicated warming temperatures for much of western North America, and changes to snowpack conditions. Our assessment of climate change impacts indicated 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) would persist on May 1 at elevations currently used by wolverines for denning. This was true, on average, across the range of climate models used out to approximately year 2055.

Our 2023 Response:

In the 2023 wolverine SSA report addendum, we expanded upon our climate analysis from the 2018 SSA report. Both SSA documents went through an independent, scientific peer review process. The assessment of the climate modeling results, presented below under

Climate Change,

and applied in the “Summary of Future Condition” discussion, replaces and supersedes the analysis of modeling results presented in the February 4, 2013, proposed listing rule (78 FR 7864) and the October 13, 2020, withdrawal document (85 FR 64618). We acknowledge there are uncertainties around the nature of the wolverine's relationship with cold and snowy conditions (see

Areas of Uncertainty for Wolverine Habitat Needs,

below). Cold and snowy conditions at high elevations favored by wolverines in the contiguous United States are expected to decrease, with spring snowpack at denning elevations decreasing as much as 50 percent in some areas.

(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 2020 Response Summarized:

In the October 13, 2020, withdrawal document (85 FR 64618), we referred to our response to

(2) Comment

for a discussion of effective population size (85 FR 64618 at 64620). Regarding recent occurrences of wolverines in the contiguous United States, we noted that wolverines had recently been found in areas where they were once extirpated in the contiguous United States. See “Population Abundance and Density” in the October 13, 2020, withdrawal document (85 FR 64618 at 64634-64636) for more information.

Our 2023 Response:

The best available estimate of effective population size for the Northern Rocky Mountains continues to be that provided by Schwartz et al. 2009 (p. 3226): 35 (credible interval = 28-52). We estimated the effective population size of wolverines in the North Cascades to be four (Service 2023, p. 27). We are not aware of any other estimates of the effective population size of North American wolverines in the contiguous United States. See also our response to

(2) Comment,

above, and

Effective Population Size in the Contiguous United States,

below, for more information.

We have gathered updated occurrence information in our 2023 wolverine SSA report addendum (Service 2023, figure 2). We acknowledge that there are recent occurrences of wolverines in the western United States in areas where they have not been reported for years or very rarely (California, Colorado, Oregon, and Utah). These occurrences outside of the known breeding distribution are encouraging, but there is no evidence of breeding population expansion into California, Colorado, Oregon, and Utah.

(18) Comment:

We received comments from several western States presenting clarifications or updates to incidental trapping events and trapping regulations.

Our 2020 Response Summarized:

We noted that trapping or hunting of wolverines was not allowed in any western State (with the exception of Alaska, which was not included in the DPS in our February 4, 2013, proposed listing rule (78 FR 7864)). Legal protections for wolverines are codified in western State laws and regulations concerning hunting and trapping. Since 2013, there has been a zero quota for trapping or harvest of wolverines in Montana. We described the documentation of incidental trapping of wolverines in the contiguous United States (as recently as December 2017) and noted that not all events resulted in mortality. We acknowledged that both Idaho and Montana are implementing trapper education programs to minimize nontarget wolverine captures.

Our 2023 Response:

We gathered updated information from States within the North American wolverine's range about incidental trapping, trapping regulations, and measures taken by States to prevent incidental trapping of wolverines. Lethal incidental trapping of wolverines has been minimal (1 to 2 animals per year), primarily occurring in Idaho and Montana. In the

Overutilization for Commercial, Recreational, Scientific, or Educational Purposes

discussion, below, we provide an assessment of incidental trapping and the measures States are taking to reduce incidental trapping of wolverines.

(19) Comment:

Several States provided comments in response to our February 4, 2013, proposed listing rule (78 FR 7864) and our October 18, 2016, reopening of the public comment period (81 FR 71670) indicating their disagreement with our determination of a wolverine DPS for the contiguous United States. Specifically, some commenters stated that the criteria of significance should be reevaluated, noting that the February 4, 2013, proposed listing 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 February 4, 2013, proposed listing 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. The commenter pointed out that 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. The commenter asserted that our characterization in the February 4, 2013, proposed listing 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 2020 Response Summarized:

In light of the updated analysis and new information included in the 2018 wolverine SSA report, we reevaluated wolverines in the contiguous United States under our DPS policy. We concluded that the population of wolverines in the contiguous United States was not discrete in relation to the remainder of the species in North America. As a result, in 2020, the population of wolverines in the contiguous United States was not a listable entity under section 3(16) of the Act. See Distinct Population Segment in the October 13, 2020, withdrawal document (85 FR 64618 at 64627-64631) for more information.

Our 2023 Response:

As stated above, in this final rule we provide our revised evaluation of discreteness and significance under the DPS policy of the segment of the North American wolverine occurring in the contiguous United States considering new information. We also explain how new information has led us to different conclusions from previous DPS analyses. The analysis contained in this rulemaking supersedes and replaces any previous DPS analysis for the segment of the North American wolverine occurring in the contiguous United States.

Regarding the commenter's concern with the significance analysis, we have determined, as we did in the February 4, 2013, proposed listing rule, that there is evidence that the loss of the wolverine in the contiguous United States would result in a significant gap in the range of the taxon. Based upon the loss of approximately 58,998,140 acres (238,757 km

2

) of high-quality wolverine habitat from the southern extent of the range and the adaptive potential that part of the range provides against oncoming climate change impacts, and the 12-degree latitudinal gap in the wolverine's range that would result if the U.S. population was lost, we determine that the loss of the contiguous U.S. wolverine population would result in a significant gap in the range of the taxon. Thus, the DPS meets the definition of significant in our DPS policy. For more information see

Analysis of Significance,

below.

Regarding the commenter's assertion that wolverines in the contiguous United States are connected to Canada, which relates to the discreteness analysis of our DPS policy, we do not consider wolverines in the contiguous United States to be genetically or morphologically discontinuous from wolverines in Canada (McKelvey et al. 2014, entire; Pilgrim and Schwartz 2018, entire; Sawaya et al. 2023, entire). Therefore, wolverines in the contiguous United States are not discrete based on marked separation from other populations of the same taxon. However, we determined that the wolverine meets the discreteness criterion in our DPS policy (61 FR 4722; February 7, 1996), as delimited by the international boundary with Canada and given differences in control of exploitation, conservation status, and regulatory mechanisms that are significant in light of section 4(a)(1)(D) of the Act. See

Analysis of Discreteness,

below, for more information.

Finally, regarding the commenter's point about our characterization in the February 4, 2013, proposed listing rule of trapping in Canada versus the contiguous United States, we have considered updated trapping information in our DPS analysis. New information available since the publication of our October 13, 2020, withdrawal document (85 FR 64618) indicates that overharvest from trapping in Canada was likely causing more of an impact than previously thought. Recent studies show that harvest levels in portions of southeastern British Columbia and southwestern Alberta were unsustainable and causing population declines (Mowat et al. 2020, entire; Barrueto et al. 2022, entire) and could negatively impact movement of individuals from Canada to the contiguous United States (Sawaya 2023, pers. comm.). We now conclude that the differences between Canada and the United States in control of exploitation are significant in light of section 4(a)(1)(D) of the Act and the wolverine population in the contiguous United States meets the DPS policy's standard for “discreteness.” See

Analysis of Discreteness,

below, for more information.

We conclude that the population of wolverines in the contiguous United States is discrete and significant in relation to the remainder of the species in North America. For our complete DPS analysis, see Distinct Population Segment Analysis for Wolverine in the Contiguous United States, below.

Comments Received in Response to Our November 23, 2022, Publication

As stated above, on November 23, 2022, we published a document in the

Federal Register

(87 FR 71557) soliciting new information to update the wolverine SSA so that we could reevaluate whether the North American wolverine occurring in the contiguous United States is a distinct population segment and, if so, whether the distinct population segment meets the definition of an endangered or threatened species under the Act. This document also notified the public that the February 4, 2013, proposed listing rule (78 FR 7864) had been reinstated as a result of court action. In response to the November 23, 2022, publication, we received additional information including survey results, reports, documented mortalities, management efforts, and recent wolverine literature that we evaluated and incorporated as appropriate into our wolverine SSA report addendum. Although not requested, we also received comments from submitters on topics related to determinations regarding wolverine, including whether the wolverine should or should not be listed as an endangered or threatened species under the Act. The comments we received are similar to those we present and respond to above.

Peer Reviewer Comments on the 2023 Wolverine SSA Report Addendum

We received comments from three peer reviewers on the draft wolverine SSA report addendum. We reviewed all comments we received from the peer reviewers for substantive issues regarding the information contained in the wolverine SSA report addendum, as well as any new information. The peer reviewers generally provided additional references, clarifications, and suggestions, including further definitions of some of the terms used in the wolverine SSA report addendum. We updated the wolverine SSA report addendum based on the peer reviewers' comments, including revising some of our adaptive capacity scores, clarifying specific points where appropriate, and adding additional details and suggested references where needed. Peer reviewer comments are addressed in the following summary.

(PR1) Comment:

Regarding our climate change analysis, one peer reviewer did not agree with our initial characterization of the shared socioeconomic pathway (SSP) 5-8.5 emissions scenario as worst case, and stated there are possible scenarios that could be more extreme. They also recommended the wolverine SSA report addendum more clearly point out the uncertainty around the climate models and emissions scenarios by stating the scenarios are representative of a large

portion of plausible outcomes, but not all.

Our Response:

We addressed the peer reviewer's concern by removing mention of likelihood when discussing specific emissions scenarios. We also modified the text to include the latest guidance from the White House Office of Science and Technology Policy on Selecting Climate Information to Use in Climate Risk and Impact Assessments (OSTP 2023, entire), which recommends using SSP5-8.5 as an upper bounding scenario. We applied SSP5-8.5 as the upper bound to estimate future snow cover available for wolverines within the selected domains.

(PR2) Comment:

A peer reviewer questioned why we used the SSP2-4.5 and SSP5-8.5 emissions scenarios for our future condition analysis. They suggested we use SSP1-1.9 instead of SSP2-4.5 since it is the opposite extreme of SSP5-8.5.

Our Response:

For our future analysis, we used SSP2-4.5 because that emissions scenario is closest to the current emissions trajectory we are on now, which provides a plausible lower boundary estimate of future snow cover available for North American wolverines. The Intergovernmental Panel on Climate Change (IPCC) has recently deemed our ability to limit warming to 1.5 °C (2.7 °F) (SSP1-1.9) as “impossible” with no or limited overshoot in its 2022 gap analysis (Riahi et al. 2022, p. 298). Scenario SSP5-8.5 reflects a no-emissions mitigation policy, which provides a plausible upper boundary estimate of available future snow cover.

(PR3) Comment:

A peer reviewer was concerned that the wolverine SSA report addendum did not list snow as an important attribute when studies have shown dens are concordant with spring snow coverage. The peer reviewer disagreed with our reasoning for excluding snow, which was because we do not know how it impacts survival and reproduction, and stated we should also remove food habits, physical features, and home range size since it is not clear how any of these impact survival and reproduction. They believe the case for snow is much stronger than any of these other factors.

Our Response:

We considered the information provided and addressed the peer reviewer's concern by updating the wolverine SSA report addendum to include snow as an important attribute of wolverine habitat.

(PR4) Comment:

One peer reviewer was concerned about the use of spring snow cover for distribution. They questioned our use of the term “persistent spring snow” and the May 15 end date that is often associated with the term. The peer reviewer recommended analyzing snow cover between February and March, when young are newborn and most in need of thermal cover in natal dens. The reviewer believed that any analysis of climate change effects at those more critical times for denning would not likely show impacts.

Our Response:

We used the term “persistent spring snow” in the wolverine SSA report addendum because it is a term frequently used in the scientific literature for wolverines and appears to be correlated to the wolverine's circumpolar distribution. Snow model outputs for May 1 are presented in the 2023 wolverine SSA report addendum. May 1 was used based on previous studies documented in the 2018 SSA (Service 2018, p. 26), indicating wolverine den site abandonment generally occurs before May 1. We acknowledge that young kits are in natal dens usually from mid-February to mid-March, so the use of May 1 snow projections is a conservative approach, but one which is consistent with the literature.

As described in the wolverine SSA report addendum, there are a number of hypotheses for why wolverines prefer cold and snowy habitats, and not all of them are limited to denning (

i.e.,

easier to get food, more food caching sites, etc.). These things could be important for adults throughout the breeding cycle or for juveniles as they become more independent from their mothers. We also discuss the possibility of other factors that are correlated to persistent spring snow, such as low temperatures (also analyzed in Copeland et al. 2010, entire), being the causal mechanisms for the observed relationship. In the wolverine SSA report addendum, we acknowledge wolverines have been documented denning in areas without persistent spring snow (Aronsson and Persson 2017, p. 266; Copeland et al. 2010, pp. 240-242; Fisher et al. 2022, p. 8; Jokinen et al. 2019, pp. 6-8; Persson et al. 2023, entire; Webb et al. 2016, pp. 1466-1467); however, this phenomenon appears to be associated with cold, high-latitude boreal or arctic forests rather than the alpine habitats used by wolverines in the contiguous United States. In the contiguous United States, there is no evidence that wolverines have denned in areas without persistent spring snow.

(PR5) Comment:

One peer reviewer recommended including potential ways wolverines could adapt their denning behavior or use smaller or shallower patches of snow for denning in response to effects from climate change.

Our Response:

We added language to the wolverine SSA report addendum to address this comment and we also included additional text that snow may be important for more than just denning. As stated above, there is no evidence that wolverines have denned in areas without persistent spring snow in the contiguous United States.

(PR6) Comment:

A peer reviewer pointed out that future recreation will not just increase due to an increase in the human population, but also because snow-dependent recreational activities will be constrained to a smaller area that still contains quality snow in the future.

Our Response:

We included text in the wolverine SSA report addendum reflecting the reviewer's comment.

(PR7) Comment:

One peer reviewer suggested adding Colorado's wolverine reintroduction plan to the wolverine SSA report addendum as a voluntary conservation measure.

Our Response:

We updated the wolverine SSA report addendum to include a description of Colorado Parks and Wildlife's previous consideration of reintroducing wolverines to Colorado as a nonessential experimental population (see 78 FR 7890, February 4, 2013). We also describe how this proposal was subsequently withdrawn in 2014 (see 79 FR 47522, August 13, 2014), when we withdrew the February 4, 2013, proposed listing rule (78 FR 7864), and that there is currently no formal proposal to reintroduce wolverines to Colorado.

(PR8) Comment:

Two peer reviewers provided additional documentation regarding roads acting as a barrier to wolverine dispersal. Both provided different situations where at least one wolverine was seen crossing roadways, including a multiple-lane highway. One peer reviewer also mentioned regularly seeing wolverine tracks crossing roadways.

Our Response:

We updated the wolverine SSA report addendum to reflect these observations and modified the text to clarify that highways can limit female gene flow in some situations, but they are not complete barriers to wolverine movements.

(PR9) Comment:

One peer reviewer questioned how the artificial cutoff of the U.S.-Canada international border influenced the results of the 2009 effective population size analysis (Schwartz et al. 2009, entire).

Our Response:

The effective population size estimate was only for the U.S. portion of the Northern Rockies, and there were no samples taken from Canada. As we stated in the wolverine SSA report addendum, connectivity to larger source

populations can alleviate the adverse effects of small effective population sizes (Frankham et al. 2014, entire). We also added a paragraph to the wolverine SSA report addendum to explain that because effective population size estimates for wolverine are small, connectivity with populations in Canada to allow for migration and gene flow is crucial to maintaining genetic diversity.

(PR10) Comment:

One peer reviewer was concerned that current data for the wolverine are not being compared to what is known historically. They specifically called out the comparison of population sizes, the distribution and abundance of wolverines in the contiguous United States, and the results of genetic studies.

Our Response:

As the peer reviewer mentioned, there is a lack of historical data to compare to current conditions. However, our assessment is a forward-looking one, based on current and future conditions, and not the change from historical conditions to current conditions.

(PR11) Comment:

One peer reviewer questioned the 40 percent decline in wolverine abundance within a national park complex in southwestern Canada (Mowat et al. 2020, entire; Barrueto et al. 2022, entire).

Our Response:

The Barrueto et al. (2022) effort is a decade-long research project that was peer reviewed and published in a scientific journal. We note that the initial population estimate was approximately 50 wolverines at the start of the study, so a 40 percent decline over 10 years results in the loss of approximately 15-20 wolverines. The wolverine SSA report addendum has been updated to provide this additional detail.

(PR12) Comment:

A peer reviewer suggested including additional detail on how species-specific trapping and snaring reduce the likelihood of incidentally capturing a wolverine.

Our Response:

We updated the wolverine SSA report addendum to include how trappers use pan tension, site selection, and snare height to reduce the likelihood of incidental capture. We also included additional information we received from the States on their efforts to reduce incidental trapping of wolverines.

(PR13) Comment:

One peer reviewer suggested that the median and quartiles presented in our modeling may not accurately capture the variability in environmental conditions. The reviewer suggested that in addition to calculating the lower-quartile, median, and upper-quartile at each individual grid cell and timestep, we should also calculate the maximum and minimum bracketing response.

Our Response:

We did not conduct the additional suggested analysis. The additional analysis would require significant work and time, and we conclude our approach includes the majority of plausible future outcomes and incorporates the best available information to inform our listing determination.

I. Final Listing Determination

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) and wolverine SSA report addendum (Service 2023, entire). 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 feet (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, which includes weasel, 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). In North America, wolverines 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 was most likely the result of unregulated trapping and predator poisoning campaigns. Following regulation of trapping and restrictions on the use of poison, the wolverine population rebounded to some extent, and their distribution expanded to refill a portion of their previously extirpated range. In the contiguous United States, wolverines are known to reproduce in Washington, Idaho, Montana, and Wyoming (Service 2023, figure 3). Solitary individuals or lone dispersing individuals have been observed in other western States (Oregon, Colorado, Utah, and California), but there is no evidence of reproduction in the contiguous United States outside of the Northern Rocky Mountains in Idaho, Montana, and Wyoming and the Cascade Mountains of Washington.

Regulatory and Analytical Framework

Regulatory Framework

Section 4 of the Act (16 U.S.C. 1533) and the implementing regulations in title 50 of the Code of Federal Regulations set forth the procedures for determining whether a species is an endangered species or a threatened species, issuing protective regulations for threatened species, and designating critical habitat for endangered and threatened species. In 2019, jointly with the National Marine Fisheries Service, the Service issued a final rule that revised the regulations in 50 CFR part 424 regarding how we add, remove, and reclassify endangered and threatened species and the criteria for designating listed species' critical habitat (84 FR 45020; August 27, 2019). On the same day, the Service also issued final regulations that, for species listed as threatened species after September 26, 2019, eliminated the Service's general protective regulations automatically applying to threatened species the prohibitions that section 9 of the Act applies to endangered species (84 FR 44753; August 27, 2019).

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 species' expected response 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 we 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 the 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 wolverine SSA report and SSA report addendum document the results of our comprehensive biological review of the best scientific and commercial data regarding the status of the North American wolverine, including an assessment of the potential threats to the subspecies occurring in the contiguous United States. The wolverine SSA report and SSA report addendum do not represent our decision on whether the North American wolverine should be listed as an endangered or threatened species under the Act. However, they do 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.

To assess viability of the North American wolverine occurring in the contiguous United States, we used the three conservation biology principles of resiliency, redundancy, and representation (Shaffer and Stein 2000, pp. 306-310). Briefly, resiliency is the ability of the species to withstand environmental and demographic stochasticity (for example, wet or dry, warm or cold years); redundancy is the ability of the species to withstand catastrophic events (for example, droughts, large pollution events), and representation is the ability of the species to adapt to both near-term and long-term changes in its physical and biological environment (for example, climate conditions, pathogen). In general, species viability will increase with increases in resiliency, redundancy, and representation (Smith et al. 2018, p. 306). Using these principles, we identified the subspecies' ecological requirements for survival and reproduction at the individual, population, and species levels, and described the beneficial and risk factors influencing the subspecies' viability.

The SSA process can be categorized into three sequential stages. During the first stage, we evaluated the individual subspecies' life-history needs. The next stage involved an assessment of the historical and current condition of the subspecies' 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 subspecies' responses to positive and negative environmental and anthropogenic influences. Throughout all of these stages, we used the best available information to characterize viability as the ability of a species (which, under the Act, includes any subspecies of fish or wildlife or plants, and any DPS of any species of vertebrate fish or wildlife which interbreeds when mature) to sustain populations in the wild over time. We use this information to inform our regulatory decision.

Later in this document, we present a summary of the key results and conclusions from the 2018 wolverine SSA report and 2023 wolverine SSA report addendum; the full SSA report and SSA report addendum can be found at Docket No. FWS-R6-ES-2023-0216 on

https://www.regulations.gov

and at

https://ecos.fws.gov/ecp/species/5123.

Distinct Population Segment

Pursuant to the Act, we must consider for listing any species, subspecies, or, for vertebrates, any 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 (DPS policy; 61 FR 4722, February 7, 1996). The DPS policy addresses the recognition of DPSs for potential listing actions. The DPS 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 Lists of Endangered and Threatened Wildlife and Plants (Lists), reclassification, and removal from the Lists. 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.

We have conducted several DPS analyses of wolverines in the contiguous United States since 2010 in response to new information and legal challenges. We first found that the population qualified as a DPS in our 2010 12-month finding (75 FR 78030; December 14, 2010) on a petition to list the population as a DPS. We reaffirmed and summarized this finding in our February 4, 2013, proposed listing rule (78 FR 7864). In 2020, we reversed our previous finding, based on information at the time which suggested the population was not discrete from wolverine populations in Canada (85 FR 64618; October 13, 2020). Below, we provide our revised evaluation of discreteness and significance under the DPS policy of the segment of the North American wolverine occurring in the contiguous United States. Where necessary and appropriate below, we explain how new information has led us to different conclusions from previous DPS analyses. The analysis contained in this rulemaking supersedes and replaces any previous DPS analysis for the segment of the North American wolverine occurring in the contiguous United States. We determined that the contiguous U.S. population of the North American wolverine meets the discreteness criterion in our DPS policy; it is delimited by the international boundary with Canada, and there are differences between the United States and Canada regarding control of exploitation, conservation status, and regulatory mechanisms that are significant in light of section 4(a)(1)(D) of the Act. We then determined that the North American wolverine population occurring in the contiguous United States is significant because its loss would result in a significant gap in the range of the taxon.

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 find marked separation from other populations to support discreteness of the contiguous U.S. wolverine population. We also did not find marked separation to support discreteness in our October 13, 2020, withdrawal (85 FR 64618). Our review of the new information presented in the 2023 wolverine SSA report addendum has not altered that conclusion; we continue to find 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 or morphologically discontinuous from wolverines in Canada based on genetic information that supports that Canadian wolverines repopulated the contiguous United States over the past several decades and there are no unique haplotypes in the contiguous U.S. population (McKelvey et al. 2014, entire; Pilgrim and Schwartz 2018, entire; Sawaya et al. 2023, entire). Therefore, wolverines in the contiguous United States are not discrete based on marked separation from other populations of the same taxon.

We next evaluate whether the wolverine population in the contiguous United States is discrete based on the international boundary with Canada. We separately consider below whether there is discreteness based on differences between the two countries in terms of control of exploitation, management of habitat, conservation status, or regulatory mechanisms that are 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 Control of Exploitation

In our 2010 12-month finding (75 FR 78030; December 14, 2010) and 2013 proposed listing rule (78 FR 7864; February 4, 2013), we noted that differences in control of exploitation exist between the United States and Canada, but concluded those differences did not result in discreteness because the differences favored the contiguous U.S. population, the population that is at risk. In the wolverine 2018 SSA report, we noted that trapping or hunting of wolverines is currently prohibited in the contiguous United States and is allowed in Canada (Service 2018, pp. 68-69). In that 2018 SSA report, we included an analysis of trapping efforts in southern Canada and trapping effort along the U.S.-Canada border, and based on that analysis, we found trapping to be limited. We again concluded in our October 13, 2020, withdrawal document (85 FR 64618) that the differences in exploitation were not significant in light of section 4(a)(1)(D) of the Act (inadequacy of existing regulatory mechanisms).

However, new information available since the publication of the October 13, 2020, withdrawal document indicates that trapping in Canada was likely causing more of an impact than previously thought. Recent studies show that harvest levels in portions of southeastern British Columbia and southwestern Alberta were unsustainable and causing population declines (Mowat et al. 2020, entire; Barrueto et al. 2022, entire). The areas evaluated are close enough to the international border that dispersing individuals would be likely to provide important genetic diversity and demographic rescue to the population in the contiguous United States. Harvest levels in Canada could negatively impact movement of individuals from Canada because, with reduced populations in Canada, there is less pressure on individuals to move south to areas in the United States to find suitable vacant home ranges (Sawaya

2023, pers. comm.). Furthermore, female wolverines appear less likely to disperse long distances or across major roadways compared to males (Sawaya et al. 2019, pp. 621-23). According to the latest genetic analyses, virtually all of the recent movement of wolverines from Canada to the United States appears to be by males (Sawaya et al. 2023, pp. 12-14, 17). Although there is now a trapping moratorium in southeastern British Columbia (British Columbia 2022, p. 76), it is unclear how long the moratorium will be in place or what the legacy effects of recent overharvest in southern British Columbia will be. In addition, trapping continues to be allowed in portions of southern Alberta. We conclude that harvest in Canada will continue to be an impediment to effective dispersal of wolverines into the United States. This, in turn, is likely to impact future genetic integrity of the population in the contiguous United States and limit the ability for demographic rescue should wolverines decline in number within the contiguous United States. Thus, we now conclude, based on new information, that the differences between Canada and the United States in control of exploitation are significant in light of section 4(a)(1)(D) of the Act. Existing regulations in Canada have been inadequate to address this exploitation. Alberta continues to allow trapping in areas important for potential dispersing wolverines, and there is uncertainty on the length and effectiveness of the trapping moratorium in British Columbia and the long-term population effects of the recent overharvest there. As a result, we conclude the wolverine population in the contiguous United States meets the standard of “discreteness” and we use the international border between the United States and Canada to define the northern boundary of the contiguous U.S. wolverine discrete population.

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

In the 2013 proposed listing rule (78 FR 7864; February 4, 2013) and October 13, 2020, withdrawal document (85 FR 64618), we stated that management activities (

e.g.,

timber harvest, wildland firefighting, prescribed fire, and silviculture) can modify wolverine habitat, but this species appears to be little affected by changes to the vegetative characteristics of its habitat. However, recent research in Canada indicates that wolverines and other carnivores can be displaced from habitat that is subject to human disturbance that includes harvest cut-blocks in forested habitat (Frey et al. 2020, entire). That said, most wolverine habitat in the contiguous United States occurs at high elevations in rugged terrain that is not usually conducive to intensive forms of silviculture and timber harvest. Although recent information indicates wolverines may be affected by disturbance from some types of habitat management, these disturbances occur in both the contiguous United States and southern Canada, where forested alpine habitats are managed in relatively similar ways and are relatively limited in scope and scale in wolverine habitat. Therefore, there are no significant differences in management of habitat between the United States and Canada pursuant to 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 summarized 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 contiguous U.S. range appear to be at numbers so low that their continued existence could be at risk, especially in light of the threats to the subspecies. In the 2010 12-month 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 patches separated by unsuitable habitat. As a result, we concluded that the contiguous U.S. population of the wolverine met the discreteness criterion in our DPS policy. Consequently, we used the international border between the United States and Canada to define the northern boundary of the contiguous U.S. DPS of the North American wolverine in our December 14, 2010, 12-month finding (75 FR 78030) and our February 4, 2013, proposed listing rule (78 FR 7864).

In our October 13, 2020, withdrawal document (85 FR 64618), based on new information at the time, we concluded there were not significant differences in control of exploitation, conservation status, and management of habitat, nor other threats to the wolverine requiring regulatory mechanisms to address them, and we concluded that there are no differences in regulatory mechanisms between the United States and Canada that are significant in light of section 4(a)(1)(D) of the Act. As a result, we concluded that the contiguous U.S. population of the North American wolverine did not meet the discreteness criterion in our DPS policy. Below, we revisit discreteness based on the international border and differences in conservation status considering new information presented in the wolverine SSA report addendum.

Small Total Population Size

—Wolverine population densities vary across North America and have been described as naturally low (van Zyll de Jong 1975, p. 434) given the species' large home range, wide-ranging movements, and solitary characteristics (Service 2018, p. 56). There are far fewer wolverines in the contiguous United States (around 300) than there are in Canada (more than 15,000) and Alaska (likely in the thousands) (Committee on the Status of Endangered Wildlife in Canada (COSEWIC) 2014, pp. 36, 47; Inman et al. 2013, p. 282; Service 2018, p. 71), but this is largely 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. Even if wolverines occupied all available habitat in the contiguous United States, their populations would still be relatively small compared to Canada (

i.e.,

the population capacity estimate was 644 (95% confidence interval (CI) = 506-1881) (Inman et al. 2013, p. 282). A small population in the contiguous United States would be less of a conservation concern if there were greater connectivity with the larger populations in Canada.

Recent genetic information indicates wolverines from Canada have slowly repopulated the contiguous United States over the past century since the era of unregulated predator removal (Service 2018, pp. 45-50; Sawaya 2023, pers. comm.). We stated in the December 14, 2010, 12-month finding (75 FR 78030) that differences in population sizes between the contiguous United States and Canada were reflective of a difference in conservation status. In our October 13, 2020, withdrawal document (85 FR 64618), based on new information, we concluded that the contiguous U.S. wolverines represent a peripheral

population at the southern extent of the North American wolverine's range. Thus, we considered the small population size of wolverines in the United States to be a natural result of the limited habitat available and not reflective of a difference in conservation status. Our 2020 determination on this point was made with the understanding that there was sufficient connectivity with Canada such that dispersing wolverines could bolster the small population in the contiguous United States. However, new information on wolverine dispersal and genetic connectivity indicates that wolverines appear to be impacted by recent overharvest in Canada, barriers to female wolverine dispersal, and development in dispersal corridors between suitable habitat (Barrueto et al. 2022, p. 4; Sawaya et al. 2023, pp. 12-14; Balkenhol et al. 2020, p. 799). Because of this, the small population in the contiguous United States is more at risk from future threats impacting population resiliency. We now conclude that the difference in population size on the contiguous U.S. side of the international border is 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

—In our December 14, 2010, 12-month finding (75 FR 78030) and February 4, 2013, proposed listing rule (78 FR 7864), in support of our conclusion that differences in conservation status between the United States and Canada exist that are significant in light of section 4(a)(1)(D) of the Act, we discussed the difference in wolverine effective population size between the contiguous United States and Canada. The 2013 proposed listing 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 provided in our SSA report (Service 2018, pp. 46-47), effective population sizes (N

e

) are typically smaller than census population sizes. N

e

is the number of individuals in a population that would result in the same loss of genetic diversity, inbreeding, and genetic drift, if they behaved in the manner of an idealized population (equal sex ratio, random mating, all adults producing offspring, equal numbers of offspring per parent, and a constant number of breeding individuals across generations) (Frankham 1995, p. 96). The concept of effective population size relates to population viability because, as a general rule, closed populations with random mating that have effective population sizes (1) below 50 are at higher risk of inbreeding depression, and (2) below 500 are more likely to lose genetic variation important to maintaining long-term evolutionary potential. In addition, small, isolated populations are more vulnerable to extinction through interactions between environmental, genetic, and demographic factors (Caughley 1994, pp. 221-227). Importantly, the concept and guidelines for genetically effective population size were developed for a single, isolated population (Laikre et al. 2016, p. 280). Fragmentation can further exacerbate inbreeding depression and genetic loss, while connectivity to larger source populations can alleviate the adverse effects of small effective population sizes (Frankham et al. 2014, p. 60).

In our October 13, 2020, withdrawal document (85 FR 64618), we acknowledged the low effective population size of wolverines in the contiguous United States but found this was not a concern given the evidence of genetic connectivity between the United States and Canada. We stated the currently known spatial distribution of genetic variability in wolverines in North America appeared 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) 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. We stated that 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 concluded that this level of migration from the north had already been occurring following the end of intense predator removal campaigns that affected this subspecies. Given observations of wolverines moving vast distances over varied terrain and across the U.S.-Canada border, our 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 U.S. wolverines, we believed that wolverines in the contiguous United States were not separated genetically from the larger population in Canada. In our October 13, 2020, withdrawal document (85 FR 64618), we concluded that wolverines in the contiguous United States exhibit genetic and phenotypic similarities with wolverines in Canada that implied connectivity with Canada. As such, we concluded in that withdrawal document that it was not biologically appropriate to consider the low effective population size of wolverines on the contiguous U.S. 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.

In our 2023 wolverine SSA report addendum, we summarized our evaluation of the available information related to the effective population size of wolverines in the contiguous United States, recent trapping/harvest in Canada, and genetic connectivity of wolverines between the United States and Canada. We are not aware of any new estimates of effective population size for wolverines in the contiguous United States; therefore, the N

e

estimate of the wolverine population in the Northern Rocky Mountains (35) provided by Schwartz et al. (2009) represents the best available scientific information regarding effective population sizes in the U.S. portion of the Northern Rocky Mountains (Service 2023, p. 27). In the 2023 wolverine SSA report addendum, we estimated the effective population size of the wolverine population in the North Cascade Mountains, resulting in an estimate of N

e

= 4 (Service 2023, p. 27). When viewed in isolation, the overall effective population sizes for wolverines in the contiguous United States are under the conservation thresholds for short- and long-term genetic health (50 and 500, respectively). New information suggests recent trapping harvest in southwestern Canada resulted in population declines in some areas that may be important sources of dispersing individuals to the contiguous United States (Service 2023, pp. 41-42). Furthermore, new information shows that female wolverine movement is influenced by major transportation corridors and that the Trans-Canada Highway could be an impediment to female movement (Service 2023, p. 28). Overall, the effective population size estimates of wolverines in the contiguous United States are small

compared to conservation rules-of-thumb and presumably smaller than the effective population size of wolverines in Canada. Only one or two migrants per generation are likely needed to achieve genetic population connectivity (Cegelski et al. 2006, p. 13); however, based on new information on gene flow and dispersal, we cannot assume this level of immigration from Canada is occurring. The contiguous U.S. population may be at risk of impacts from low effective population size without sufficient gene flow with Canada. We now conclude that the difference in effective population size on the U.S. side of the international border results in a significant difference in conservation status in light of section 4(a)(1)(D) of the Act as it applies to discreteness.

Habitat Fragmentation

—In our December 14, 2010, 12-month finding (75 FR 78030) and February 4, 2013, proposed listing rule (78 FR 7864), we stated that wolverine habitat in the contiguous United States consists of small, isolated areas 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). This was used to support our justification for discreteness.

The breeding range of wolverines in the contiguous United States largely exists in high-elevation alpine forested habitats. Those alpine areas with established wolverine home ranges are separated by expanses of lower elevation valley habitats that are not conducive to wolverine home range establishment but do provide varying levels of connectivity between home ranges or subpopulations. In Canada and Alaska, habitats are more contiguous and much less fragmented than wolverine habitat in the contiguous United States. The fragmented nature and distribution of wolverine habitat in the contiguous United States puts wolverines occurring in the contiguous United States at higher risk of impacts from climate change and other stressors compared to wolverines occurring in Canada and Alaska. We conclude that the difference in habitat fragmentation on the contiguous U.S. side of the international border results in a significant 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

Wolverines are currently protected under various State regulatory designations in the States where the species occurs in the western United States (Service 2023, table 10). In Canada, provincial designations for the wolverine include endangered in Labrador, and threatened in Ontario and Québec (“threatened” is equivalent to endangered in Québec), with the remaining provincial designations ranging from no ranking to sensitive or special concern to the Vancouver Island population's designation as imperiled (COSEWIC 2014, p. 44).

Current regulatory mechanisms prohibit trapping or harvest of wolverines in the contiguous United States, while trapping is legal in Canada and occurs in parts of the range that could be a source of important dispersers to the contiguous United States. We acknowledge that there is currently a trapping moratorium in a portion of British Columbia resulting from studies showing population declines in that area related to trapping (Service 2023, pp. 44-45). However, that moratorium is temporary and only covers a portion of the Canadian range (

e.g.,

it does not include Alberta). As discussed above, there are significant differences in control of exploitation that may be impeding movement of wolverines, from Canada to the contiguous United States. We conclude that there are differences in regulatory mechanisms related to control of exploitation between the United States and Canada that are significant in light of section 4(a)(1)(D) of the Act.

Discreteness Conclusion

Based on our updated analysis described above and supported by information in the wolverine SSA report and the wolverine SSA report addendum, the contiguous U.S. population of the North American wolverine meets the discreteness criterion in our DPS policy (61 FR 4722; February 7, 1996). It is delimited by the international boundary with Canada, given differences in control of exploitation, conservation status, and regulatory mechanisms that are significant in light of section 4(a)(1)(D) of the Act. After determining that a vertebrate population is discrete, we are required to complete an analysis to determine if the population in question is significant according to our DPS policy; that analysis follows.

Analysis of Significance

If we determine a population segment is discrete, its biological and ecological significance will then be considered in light of Congressional guidance that the authority to list DPSs be used sparingly while encouraging the conservation of genetic diversity. In carrying out this examination, we consider available scientific evidence of the population's importance to the taxon to which it belongs (

i.e.,

the North American wolverine). Our DPS policy states that this consideration may include, but is not limited to: (1) persistence of the discrete population segment in an ecological setting unusual or unique for the taxon; (2) evidence that loss of the discrete population segment would result in a significant gap in the range of the taxon; (3) evidence that the discrete population segment represents the only surviving natural occurrence of a taxon that may be more abundant elsewhere as an introduced population outside its historical range; or (4) evidence that the discrete population segment differs markedly from other populations of the species in its genetic characteristics. Below, we address considerations 1, 2, and 4. Consideration 3 does not apply to the continental U.S. wolverine population because North American wolverines are distributed widely across Alaska and Canada.

In our December 14, 2010, 12-month finding (75 FR 78030), we conducted an exhaustive analysis of the significance of the contiguous U.S. population of the North American wolverine; this analysis was incorporated by reference into our February 4, 2013, proposed listing rule (78 FR 7864). In the analysis, we concluded that the wolverine population in the contiguous United States is significant because its loss would result in a significant gap in the range of the taxon. In our October 13, 2020, withdrawal document (85 FR 64618), we did not present an assessment of significance under the DPS policy because, at that time, we determined that the wolverine population in the contiguous United States was not discrete, and thus there was no need to assess significance. Because we have now determined the wolverine population in the contiguous United States is discrete, we reviewed and present an update to our 2010 and 2013 assessment of the significance of the wolverine population occurring in the contiguous United States using the best available information.

Unusual or Unique Ecological Setting

Wolverines occupy a variety of habitats within North America, including Arctic tundra, subarctic-alpine tundra, boreal forest, mixed forest, redwood forest, and coniferous forest (Banci 1994, p. 114). Wolverines in the contiguous United States exist in an ecosystem that includes high-elevation, remote, rugged, alpine forested terrain and non-forested habitats around the tree line that retain snowpack into the spring. The ecoregions inhabited by wolverines in the contiguous United States are also present in large portions of their occupied range in Canada and Alaska (Service 2018, appendix A).

Wolverines in the contiguous United States appear to use habitat attributes that are similar to wolverine populations in Canada and Alaska, where wolverines also use alpine habitats, and do not appear to exist in an unusual or unique ecological setting. Thus, we again do not rely on this factor when determining that the wolverine in the contiguous United States is significant to the taxon as a whole.

Significant Gap in the Range of the Taxon

Wolverines once lived throughout the North American Rocky Mountains from Alaska and Canada, south through Colorado and into New Mexico, and in the North Cascades of Washington and the Sierra Nevada Range of California. During the late 1800s and early 1900s, the wolverine population declined or was extirpated in much of the contiguous United States (Service 2018, p. 1). Wolverines have since recolonized parts of the contiguous United States, and the current breeding range includes the Southern Rocky Mountains of Idaho, Montana, and Wyoming and the Cascades of Washington (Service 2023, figure 3). Individual wolverines have been documented in California, Colorado, Oregon, and Utah; however, breeding populations are not known to exist in these areas. The contiguous United States represents the southernmost extent of the wolverine's range in North America.

Our significance determination in the December 14, 2010, 12-month finding (75 FR 78030) concluded that the loss of wolverines in the contiguous United States would result in a significant gap in the range of the taxon. This determination was based on an estimate of the historical range (not current range) of wolverine in the contiguous United States. This relied on a latitudinally-based interpretation of historical range in the contiguous United States, the majority of which was unoccupied at the time the estimation was made and remains unoccupied by wolverines. We stated in 2010 that the loss of the population in the contiguous United States would be significant because it would substantially curtail the range of the wolverine by moving the southern range terminus approximately 15 degrees latitude to the north (or approximately 40 percent of the presumed latitudinal extent of the wolverine's range in North America). For reference, the U.S. border with Canada is 49 degrees North latitude. Fifteen degrees south of the border (at 34 degrees North latitude), the assumed 15-degree gap in latitude (49 degrees North minus 34 degrees North) presented in the DPS analysis in the December 14, 2010, 12-month finding (75 FR 78030), lands on 34 degrees North latitude, which runs through western States, including southern California and approximately the middle of Arizona and New Mexico, significantly south of the currently occupied range of wolverine in United States.

During the development of our 2018 wolverine SSA report and 2023 SSA report addendum, we conducted an extensive analysis of the recent and historical occurrence records for wolverines in the contiguous United States (Service 2018, pp. 12-16; Service 2023, pp. 3-14). Our updated significance analysis is based on an updated, spatially explicit assessment of the current range of wolverines in the contiguous United States. We used the current range (Service 2023, figure 2) to provide a more accurate reflection of the range currently being used by populations of wolverines in the contiguous United States supported by the best available information. By focusing on the current range, and not the historical range, we avoid including large sections of the western United States that do not have high-quality wolverine habitat (southern California and northern Arizona and New Mexico) in our significance analysis, and thus we are able to better assess the significance of the population in the contiguous United States relative to the larger taxon. The current range of wolverines in the contiguous United States covers approximately 58,998,140 acres (238,757 km

2

) of high-quality wolverine habitat with recent wolverine occurrences (from 2009-2023) (Service 2023, figure 2), the loss of which would move the southern range terminus approximately 12 degrees latitude to the north.

Furthermore, the southernmost portion of the range may be important for conservation, as it may allow for unique adaptive potential in the face of a changing global climate and future reduction in cold and snowy conditions. Populations on the periphery of species' ranges tend to be given lower conservation priority because they are thought to exist in low-quality habitats and are also thought to be the populations that are least likely to survive a reduction in range (Wolf et al. 1996, p. 1147). However, this tendency presumes that the ultimate cause of the species' extinction will be one that operates by eroding away the species' range beginning at the periphery and progressing to the center. This presumption is based on biogeographical information that habitat and population densities of species are highest near the center of the species' range and decline near the edge (Brown and Lomolino 1998, figure 4.16). Data from documented range collapses of species from around the world, however, illustrate that species' ranges tend to collapse to peripheral areas rather than to the center of their historical ranges (Lomolino and Channell 1995, p. 342; Channell and Lomolino 2000, pp. 84-86). Of 96 species whose last remnant populations were found either in the core or periphery of their historic ranges (rather than some in both core and periphery), 91 (95 percent) of the species were found to exist only in the periphery, and 5 (5 percent) existed solely in the center (Channell and Lomolino 2000, p. 85). Available scientific data support the importance of peripheral populations for conservation (Fraser 1999, entire; Lesica and Allendorf 1995, entire).

Based upon the loss of approximately 58,998,140 acres (238,757 km

2

) of high-quality wolverine habitat from the southern extent of the range and the adaptive potential that part of the range may provide against oncoming climate change impacts, and a 12 degree latitudinal gap in the North American wolverine's range that would result if the U.S. population was lost, we determine that the loss of the contiguous U.S. wolverine population would result in a significant gap in the range of the taxon. Thus, the DPS meets the definition of significant in our DPS policy.

Marked Genetic Differences

In the contiguous United States, small, isolated wolverine populations are likely dependent on gene flow from Canada for population persistence (Cegelski et al. 2006, pp. 208-209; McKelvey et al. 2014, entire). In the Northern Rocky Mountains, the best available genetic data indicate genetic

structuring of populations despite some dispersal (Cegelski et al. 2006, pp. 204-205, 208; Sawaya et al. 2023, pp. 12-14). Genetic structuring reflects the amount of interbreeding between different groups of an organism where more structure indicates less interaction between groups, increased genetic isolation, increased potential for inbreeding, and lower genetic diversity. Given the relatively recent recolonization of wolverines in the contiguous United States from Canada (within the last 60-70 years), nuclear genetic diversity was lower in the southern periphery of the subspecies' range in the south (Sawaya et al. 2023, pp. 9-11). Nuclear DNA analyses indicated differences in allele frequencies between the United States and Canada along the Rocky Mountains, with some areas of overlap in wolverine populations straddling the border due to male-mediated gene flow. Females appear to be segregated near the international border due to their higher rates of philopatry (the tendency of an animal to remain in or return to the area of its birth) than males and their apparently greater tendencies to avoid crossing major roadways, including the Trans-Canada Highway (Highway 1) and the Crowsnest Highway (Highway 3) in southern British Columbia (Sawaya et al. 2023, pp. 12, 17). Both highways were opened in the 1960s (British Columbia Ministry of Transportation and Highways 2001, pp. 16, 20). Since then, they have been widened in many areas, and traffic volumes have substantially increased (British Columbia Ministry of Transportation and Highways 2001, pp. 7-11, 16-21). Mitochondrial DNA patterns in the Rocky Mountains showed no unique contemporary maternal lineages detected south of the international border, which is consistent with observational data indicating that wolverines recolonized the contiguous United States from Canada within the last 60-70 years (Sawaya et al. 2023, pp. 2, 16-17). Substantially lower mitochondrial DNA diversity in the United States, as compared to mitochondrial DNA diversity in Canada, is consistent with the nuclear DNA signals of limited contemporary female gene flow between the countries along the Northern Rocky Mountain range and the wolverine's relatively recent recolonization at the southern edge of their range (Sawaya et al. 2023, p. 17).

In the North Cascades, global positioning system (GPS) tracking data show that wolverines in western Washington and southern British Columbia form a small transboundary population (Aubry et al. 2023, p. 4). Preliminary results from a large population genetics study of this transboundary population show that wolverines in the North Cascades are genetically isolated from other wolverine populations in the United States and Canada and likely went through a genetic bottleneck with few founders (Sawaya 2023, pers. comm.). The population has low heterozygosity (less than 0.5) and could be experiencing some level of inbreeding (Sawaya 2023, pers. comm.). However, there are no indications or evidence that individuals or population dynamics are being adversely affected by inbreeding depression (Sawaya 2023, pers. comm.).

As part of the multi-State wolverine occupancy surveys in 2016-2017, researchers obtained 240 wolverine DNA samples (Lukas et al. 2020, p. 846). These samples represented 26 unique females and 24 unique males (Lukas et al. 2020, p. 846). Analyses of the mitochondrial DNA control region revealed regional structuring (

i.e.,

regional grouping), with all of the samples in Idaho, Montana, and Wyoming assigned to Haplotype Wilson A (the most abundant haplotype in North America) and all of the samples in Washington assigned to Haplotype Wilson C (Lukas et al. 2020, p. 846). These results are consistent with the latest genetic analysis from the large transboundary study (Sawaya et al. 2023, entire) and previous mitochondrial DNA studies showing that the Northern Rocky Mountains and North Cascades do not appear to share any contemporary haplotypes (McKelvey et al. 2014, p. 328).

The genetic differences between the contiguous United States and Canada consist of lower genetic diversity in the United States, a difference that is a reflection of the recent recolonization of wolverines into the contiguous United States from Canada over the last century. There are no unique haplotypes present in contiguous U.S. wolverines that are not already present in larger populations in Canada and Alaska. As we noted in our analysis in the December 14, 2010, 12-month finding (75 FR 78030), this is not the kind of genetic difference that would lead us to conclude that a population is significant under our DPS policy. The DPS policy is designed to ensure the protection of important components of a species' evolutionary legacy rather than populations that simply have lower genetic diversity due to recent recolonization from a larger source population. Therefore, as in our 2010 analysis, we do not find marked genetic differences as a basis for determining significance for this DPS.

Summary for Significance

We evaluated whether the discrete population segment of wolverines in the contiguous United States is also significant, considering factors such as whether the population segment is in an ecological setting unusual or unique for the taxon; whether the loss of the discrete population segment would result in a significant gap in the range of a taxon; whether the discrete population segment represents the only surviving natural occurrence of a taxon that may be more abundant elsewhere as an introduced population outside its historical range; or whether the discrete population segment differs markedly from other populations of the species in its genetic characteristics. We conclude that the wolverine population in the contiguous United States is significant because its loss would result in a significant gap in the range of the taxon.

DPS Conclusion

Based on the best available information, we conclude that the population of wolverines in the contiguous United States is discrete and significant in relation to the remainder of the subspecies in North America. As a result, the population of wolverines in the contiguous United States is 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. We have determined that wolverines in the contiguous United States qualify as a DPS and, therefore, are a listable entity. Below, we provide a status determination of the wolverine DPS in the contiguous United States.

Summary of Biological Status and Threats

In this discussion, we review the biological condition of the DPS and its resources, and the threats that influence the DPS's current and future condition, in order to assess the DPS's overall viability and the risks to that viability.

In preparing the 2018 wolverine SSA report and the 2023 SSA report addendum, 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

). We identified uncertainties and data gaps in our assessment of the current and future status of the subspecies. We also evaluated the appropriate analytical tools to address these gaps, consulted with species experts, prepared updated maps of the known subspecies' distribution and breeding range in the contiguous United States, and evaluated new models of spring snow. In some instances, we used publications and other reports (primarily from Fenno-Scandinavia) of the Eurasian subspecies (

G. g. gulo

) as a surrogate in completing our status assessment.

Since the publication of the October 13, 2020, withdrawal document (85 FR 64618), more than 180 new publications have been issued (see list of citations in the 2023 wolverine SSA report addendum). This is a substantial amount of new information for a difficult-to-study animal like the wolverine and has added significantly to our understanding of wolverine biology. This new information has also highlighted new insights into the subspecies' biological needs, threats, and the wolverine's interactions with abiotic and biotic habitat features.

We also conducted an updated geospatial analysis to map verified wolverine occurrences and approximate breeding ranges in the contiguous United States. This was informed by recent multi-State monitoring data (Lukas et al. 2020, entire; Mosby et al. 2023, entire).

Our updated analyses, since the publication of the October 13, 2020, withdrawal document, of the current and predicted future condition for the wolverine is presented in the wolverine SSA report addendum and summarized here. Our future-condition analysis includes the potential conditions that the subspecies or its habitat may face in the future. This includes consideration of threats most likely to impact the subspecies at the population or rangewide scales in the future, including potential cumulative impacts. The spatial expansion to our climate analysis is a major improvement from the snow projections used in our 2018 SSA report, which focused only on Rocky Mountain National Park (Colorado) and Glacier National Park (Montana). We now focus on five modeling domains that overlap with occupied and potential wolverine habitat in the contiguous United States across latitudinal, longitudinal, and elevation gradients. These include: (1) Cascades (Washington); (2) Northern Rocky West (Washington, Idaho, and Montana); (3) Northern Rocky (Idaho and Montana); (4) Mid-Rocky (Idaho, Montana, and Wyoming); and (5) Southern Rocky (Colorado and New Mexico) (Service 2023, p. 49). In our updated climate assessment, we use a timeframe out to end of century for assessing future effects to North American wolverine viability from climate change and other threats. Beyond 2100, climate modeling uncertainty increases substantially. Our previous assessment considered in the October 13, 2020, withdrawal document (85 FR 64618) looked at a timeframe 50 years into the future. We conclude that end of century is a reasonable timeframe, 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 subspecies needs to maintain viability by characterizing the status of the subspecies in terms of resiliency, redundancy, and representation (Wolf et al. 2015, entire). Resiliency is having sufficiently large populations for the subspecies 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 subspecies 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 subspecies. The greater the number of populations a subspecies has distributed over a larger landscape, the better it can withstand catastrophic events.

Representation is having the breadth of genetic makeup of the subspecies 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 subspecies' range. The more representation, or diversity, a subspecies has, the more it is capable of adapting to changes (natural or human-caused) in its environment. In the absence of subspecies-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

Wolverine populations are characterized by naturally low densities. 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 and activities. The wolverine is a snow-adapted, cold-climate animal in its physiology and morphology (Telfer and Kelsall 1984, p. 1830); phylogeography (historical processes that may be responsible for past and present geographic distributions of genealogical lineages); and behavior and habits (Fisher et al. 2022, p. 7).

Wolverines consume a variety of food resources, and seasonal switching of prey is commonly observed. Unlike wolverine populations in Eurasia, wolverines in the contiguous United States rarely prey on livestock. During our extensive literature review in preparing the 2023 wolverine SSA report addendum, we discovered only two instances of wolverine depredation in the United States since our 2018 SSA report; one wolverine that had depredated sheep in Utah, and another that was caught in a chicken coop in Washington (Service 2023, pp. 10, 38).

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 (only observed in snow in the contiguous United States), and several additional months of maternal care (Service 2018, p. 22). 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.

In our 2018 wolverine SSA report, we defined the physical and ecological requirements of wolverine in the contiguous United States (see (1), (2), and (3), below). In light of new information regarding wolverine habitat associations that provides support for the wolverine's strong preference for areas with cold and snowy conditions, we have added a fourth ecological requirement (see (4), below). The requirements are:

(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 that vary with seasons;

(3) Physical/structural features (

e.g.,

talus slopes, rugged terrain) linked to reproductive behavioral patterns; and

(4) Habitats characterized by the presence of persistent spring snow (of greater than or equal to 1 meter on May 1) for survival and reproduction.

Our 2023 wolverine SSA report addendum affirms these requirements and the species characterization in our 2018 SSA report.

Habitat

Research published since our 2018 wolverine SSA report confirms that broad-level habitat selection (subspecies' range, individual home range) at the southern edge of the wolverine's distribution can be accurately predicted using a small number of high-elevation variables and terrain features (Carroll et al. 2021a, pp. 1470-1471; Aubry et al. 2023, p. 7). New evidence from around the world reinforces that snow—especially persistent spring snow—is an important predictor of broad-scale wolverine distribution and density (Aubry et al. 2023, pp. 15-16; Carroll et al. 2020, p. 8; Fisher et al. 2022, p. 10; Glass et al. 2021, entire; Mowat et al. 2020, p. 220). Within home ranges, the precise nature of the relationship between wolverine space-use and snow is complex, involving multiple snow characteristics (

e.g.,

density, depth, and melt), various phases of the wolverine lifecycle (

e.g.,

denning, feeding and food caching, within-territory movements, and dispersal) and sex-specific habitat selection (Carroll et al. 2021, p. 1469; Glass et al. 2021, entire; Heinemeyer et al. 2019, p. 16). While wolverines appear capable of occupying and reproducing in areas without persistent spring snow in some ecological contexts, at a continent-wide scale, wolverine dens outside of areas with persistent spring snow have thus far only been documented to occur in colder boreal or arctic environments in Canada and Alaska (Aronsson and Persson 2017, p. 266; Copeland et al. 2010, pp. 240-242; Fisher et al. 2022, p. 8; Jokinen et al. 2019, pp. 6-8; Webb et al. 2016, pp. 1466-1467).

In the Greater Yellowstone Ecosystem, distance to high-elevation talus, snow water equivalent (a surrogate for snow depth), and latitude-adjusted elevation were the most important environmental factors explaining selection of wolverine home ranges and habitats within home ranges (Service 2023, p. 16). These habitat variables are also known to be important in defining the wolverine's distribution (Inman et al. 2013, p. 278).

Results from dispersal suitability models developed for wolverines indicate that isolation by landscape resistance (areas that individuals are less likely to traverse due to high energy, mortality, or other biological costs) explained more of the variation in wolverine genetic differences than did isolation by distance (Balkenhol et al. 2020, pp. 795-797). This means that wolverines are moving non-randomly across the landscape in association with specific landscape features. Snow depth (average 1-year snow depth at 1-km

2

resolution), terrain ruggedness (measure of how jagged or flat the terrain is on average), and housing density (census block housing density per 1 km

2

) best predicted gene flow in wolverines (Balkenhol et al. 2020, pp. 795-797). Snow depth was the most important variable for explaining variation in genetic differences overall (Balkenhol et al. 2020, p. 790). At broad spatial scales, housing density and terrain ruggedness were the most important factors, where wolverines avoided areas of high housing density and preferred areas of terrain ruggedness, which explains the variation in wolverine genetic differences (Balkenhol et al. 2020, p. 790).

In the Cascade Range in southern British Columbia and Washington, three climatic variables (proximity to the transitional zone near the alpine tree line, number of frost-free days per year, and annual precipitation as snow) were correlated with wolverine location data (Aubry et al. 2023, p. 10). Wolverine distribution in the Cascades is constrained by climatic conditions; snowy, cold environments delimit the areas that are “overwhelmingly associated with resident wolverines” (Aubry et al. 2023, p. 16). The highest-use areas were on the eastern side of the Cascades, where alpine habitats had fewer frost-free days (Aubry et al. 2023, p. 15). This is consistent with other

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