[Federal Register Volume 79, Number 156 (Wednesday, August 13, 2014)]
[Proposed Rules]
[Pages 47522-47545]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2014-18743]



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Vol. 79

Wednesday,

No. 156

August 13, 2014

Part II





Department of the Interior





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Fish and Wildlife Service





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50 CFR Part 17





Endangered and Threatened Wildlife and Plants; Threatened Status for 
the Distinct Population Segment of the North American Wolverine 
Occurring in the Contiguous United States; Establishment of a 
Nonessential Experimental Population of the North American Wolverine in 
Colorado, Wyoming, and New Mexico; Proposed Rule

  Federal Register / Vol. 79 , No. 156 / Wednesday, August 13, 2014 / 
Proposed Rules  

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket Nos. FWS-R6-ES-2012-0107 and FWS-R6-ES-2012-0106; 4500030113]
RIN 1018-AY26; 1018-AZ22


Endangered and Threatened Wildlife and Plants; Threatened Status 
for the Distinct Population Segment of the North American Wolverine 
Occurring in the Contiguous United States; Establishment of a 
Nonessential Experimental Population of the North American Wolverine in 
Colorado, Wyoming, and New Mexico

AGENCY:  Fish and Wildlife Service, Interior.

ACTION:  Proposed rules; withdrawal.

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SUMMARY:  We, the U.S. Fish and Wildlife Service, withdraw the proposed 
rule to list the distinct population segment of the North American 
wolverine (Gulo gulo luscus) occurring in the contiguous United States 
as a threatened species under the Endangered Species Act of 1973, as 
amended (Act). This withdrawal is based on our conclusion that the 
factors affecting the DPS as identified in the proposed rule are not as 
significant as believed at the time of the proposed rule's publication 
(February 4, 2013). We base this conclusion on our analysis of current 
and future threat factors. Therefore, we withdraw our proposal to list 
the wolverine within the contiguous U.S. as a threatened species. As a 
result, we also withdraw our associated proposed rule under section 
4(d) of the Act contained in the proposed listing rule and withdraw the 
proposed nonessential experimental population designation under section 
10(j) of the Act for the southern Rocky Mountains, which published in a 
separate document on February 4, 2013.

DATES: The February 4, 2013 (78 FR 7864), proposal to list the distinct 
population segment of the North American wolverine occurring in the 
contiguous United States as a threatened species and the February 4, 
2013 (78 FR 7890), proposal to establish a nonessential experimental 
population of the North American wolverine in Colorado, Wyoming, and 
New Mexico are withdrawn as of August 13, 2014.

ADDRESSES: The withdrawal of our proposed rules, comments, and 
supplementary documents are available on the Internet at http://www.regulations.gov at Docket Nos. FWS-R6-ES-2012-0107 (proposed 
listing rule and proposed rule under section 4(d) of the Act) and FWS-
R6-ES-2012-0106 (proposed nonessential experimental population). 
Comments and materials received, as well as supporting documentation 
used in the preparation of this withdrawal, are also available for 
public inspection, by appointment, during normal business hours at: 
U.S. Fish and Wildlife Service, Montana Ecological Services Office, 585 
Shepard Way, Helena, MT 59601; telephone (406) 449-5225.

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

SUPPLEMENTARY INFORMATION: 

Executive Summary

    Why we need to publish this document. Under the Endangered Species 
Act, a species may warrant protection through listing if it is 
endangered or threatened throughout all or a significant portion of its 
range. Listing a species as an endangered or threatened species can 
only be completed by issuing a rule. We issued a proposed rule to list 
the distinct population segment (DPS) of the North American wolverine 
(Gulo gulo luscus) occurring in the contiguous United States as a 
threatened species (78 FR 7864; February 4, 2013), hereafter, referred 
to as ``wolverine'' unless otherwise noted. However, this document 
withdraws that proposed rule because we have determined that factors 
affecting the DPS cited in the proposed listing are not threats to the 
DPS such that it meets the definition of an endangered or threatened 
species under the Act. Because of our withdrawal of that action, we 
also withdraw the associated proposed rule under section 4(d) of the 
Act contained in the proposed listing rule (78 FR 7864; February 4, 
2013) and withdraw the proposed nonessential experimental population 
designation under section 10(j) of the Act for the southern Rocky 
Mountains (78 FR 7890; February 4, 2013).
    The basis for our action. Under the Endangered Species Act, we can 
determine that a species is an endangered or threatened species based 
on 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 based on new 
information and further analysis of the existing and new data, factors 
affecting the DPS cited in the proposed listing rule do not place the 
wolverine in danger of extinction now or likely to become so in the 
foreseeable future.
    Peer review and public comment. We sought comments from seven 
independent specialists to ensure that our proposed listing 
determination was based on scientifically sound data, assumptions, and 
analyses. We invited these peer reviewers to comment on our evaluation 
of the science underlying our listing proposal. We received substantive 
peer reviews from all seven reviewers. We also considered all comments 
and information we received during the comment periods. In April 2014, 
we convened a panel of experts to provide us with assessments of the 
available scientific information on the potential impacts of climate 
change on wolverines and their habitat. A report containing the results 
of that workshop can be obtained from the Service's Region 6 peer-
review Web site at the following link: http://www.fws.gov/mountain-prairie/science/PeerReviewDocs/Final_Wolverine_Panel_Report.pdf. 
That report was made available for public comment through the 
Regulations.gov Web site.

Previous Federal Actions

    Please refer to the proposed listing rule for the wolverine (78 FR 
7864; February 4, 2013) for a detailed description of previous Federal 
actions concerning this DPS.
    Following publication of the proposed rule, there was scientific 
disagreement and debate about the interpretation of the habitat 
requirements for wolverines and the available climate change 
information used to determine the extent of threats to the DPS. 
Differing interpretations of the available climate change information 
led to scientific disagreement regarding the current status of the DPS. 
In particular, some commenters and peer reviewers raised questions 
regarding:
    (1) The interpretation of scientific literature in the proposed 
rulemaking and scientific literature that may not have been readily 
available for our use in our analysis to define habitat parameters. 
Specifically, some commenters and peer reviewers questioned the basis 
for defining wolverine habitat based on persistent spring snow used by 
Copeland et al. (2010). Some peer reviewers and

[[Page 47523]]

commenters suggested that other methods of habitat definition or other 
dates used to define habitat based on persistent snow are more 
scientifically defensible and would yield very different results.
    (2) Commenters suggested that McKelvey et al. (2011) used an 
invalid habitat model developed by Copeland et al. (2010) to project 
future climate impacts to wolverine habitat, and for that reason, the 
commenters believe projections in McKelvey et al. (2011) are also 
invalid.
    (3) Commenters asserted that there is high uncertainty with 
projections made using downscaled global climate modeling, which we 
used to analyze the impacts of climate change on wolverine habitat and 
ecology.
    Based on this substantial disagreement regarding the sufficiency or 
accuracy of the available data relevant to the proposed listing, on 
February 5, 2014 (79 FR 6874), we announced a 6-month extension of the 
final determination of whether to list the wolverine DPS as a 
threatened species. We also reopened the comment period on the proposed 
rule to list the contiguous U.S. DPS of the North American wolverine 
for 90 days.
    On April 3-4, 2014, the Service and partners from wildlife agencies 
in the States of Idaho, Montana, and Wyoming convened a panel of nine 
experts in climate change, wolverines and other mammalian carnivores, 
habitat modeling, and population ecology to discuss climate-related 
habitat issues and possible future population trends for wolverines. 
The objective of this workshop was to better understand the strength of 
the relationships between climate change, wolverine habitat, and future 
wolverine population trends through dialogue with an expert panel. The 
workshop was conducted using a structured agenda with exercises and 
discussions to investigate whether and how climate change might affect 
wolverines in the contiguous United States. We did not seek consensus 
or conformity among panelists, but instead scored panelists' opinions 
and elicited discussion regarding the range of variance among expert 
opinion. The agenda was divided into four parts: defining wolverine 
habitat, evaluating future snow coverage, evaluating future habitat 
projections, and evaluating future wolverine population trends. A full 
report was generated from the workshop. The report was made available 
for public comment through the Regulations.gov Web site and is 
available as cited in this withdrawal.

Background

Species Information

    Refer to the February 4, 2013, proposed listing rule at 78 FR 7864 
for information about the wolverine's taxonomy; life history; 
requirements for habitat, space, and food; densities; status in Canada 
and Alaska; geographic range delination complexities; distribution; and 
habitat relationships and distribution.

Distinct Population Segment

    Please refer to our December 14, 2010, 12-month petition finding 
(75 FR 78030) and our February 4, 2013, proposed rule to list the North 
American wolverine (78 FR 7864) for a detailed evaluation of the 
wolverine under our DPS policy.

This Action

    Based upon our review of the public comments, comments from other 
Federal and State agencies, peer review comments, issues raised by the 
wolverine science panel workshop, and other new relevant information 
that became available since the publication of our February 4, 2013, 
listing proposal, we have determined that the North American DPS of the 
wolverine does not warrant listing as an endangered or a threatened 
species. This document therefore withdraws the proposed rule published 
on February 4, 2013 (78 FR 7864), as well as the associated proposed 
rule under section 4(d) of the Act (16 U.S.C. 1531 et seq.) (78 FR 
7864; February 4, 2013) and the proposed nonessential experimental 
population in Colorado, Wyoming, and New Mexico (78 FR 7890; February 
4, 2013).
    We have re-analyzed the effects of climate change on the wolverine 
under listing factor A (the present or threatened destruction, 
modification, or curtailment of the species' habitat or range). While 
there is significant evidence that the climate within the larger range 
of the wolverine is changing, affecting snow patterns and associated 
wolverine habitat, the specific response or sensitivity of wolverines 
to these forecasted changes involves considerable uncertainty at this 
time (see Summary of Impacts of Climate Changes, below).
    We also reevaluated all other risk factors cited in the February 4, 
2013, proposed rule, as well as any new potential risk factors that 
have come to light since the proposed rule through the public comment 
process or new information. We reaffirm our determination in the 
proposed rule that these risk factors are not threats to the DPS.

Summary of Comments and Recommendations

    The proposed rule published on February 4, 2013 (78 FR 7864), 
opened a 90-day comment period on our proposal to list the wolverine as 
a threatened species and establish a rule under section 4(d) of the Act 
for the subspecies. That comment period closed on May 6, 2013. On 
October 31, 2013, we reopened the comment period on the proposed rule 
(78 FR 65248) for an additional 30 days, ending December 2, 2013. On 
February 5, 2014, we extended our final determination of the proposed 
actions for 6 months (79 FR 6874), and at that time we reopened the 
comment period for another 90 days, ending May 6, 2014. We also 
contacted appropriate Federal and State agencies, scientific experts 
and organizations, and other interested parties and invited them to 
comment on the proposal. Newspaper notices inviting public comment were 
published in newspapers of general circulation in each of the Service 
regions within the DPS. We held several public hearings throughout the 
range of the DPS; these were held in Boise, Idaho, on March 13, 2013; 
in Lakewood, Colorado, on March 19, 2013; and in Helena, Montana, on 
March 27, 2013. All substantive information provided during the comment 
periods and at the hearings has either been used to support this 
withdrawal or is addressed below.

Peer Reviewer Comments

    In accordance with our peer review policy published on July 1, 1994 
(59 FR 34270), we solicited expert opinion from seven knowledgeable 
individuals with scientific expertise that included familiarity with 
the wolverine in the contiguous U.S. DPS and its habitat, biological 
needs, and threats. We received responses from all seven of the peer 
reviewers.
    We reviewed all comments received from the peer reviewers for 
substantive issues and new information regarding the proposed listing 
of the DPS of the North American wolverine. Five peer reviewers 
generally concurred with our methods and conclusions and provided 
additional information, clarifications, and suggestions to improve the 
rule, while two peer reviewers disagreed substantially with the 
conclusions in our proposed rule. Peer reviewer comments are addressed 
in the following summary and are used to support this withdrawal 
document as appropriate.
    (1) Comment: Peer reviewers and commenters stated that the 
assessment in the proposed rule of the impacts of winter recreation on 
wolverines

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understated the potential effect of this risk factor. Commenters stated 
that there are significant gaps in our knowledge of the potential 
effects of winter recreation on wolverines and recommended more caution 
in how we approach the subject.
    Our Response: We agree that there is significant uncertainty about 
many aspects of wolverine biology and the many potential risk factors 
that may affect the species. Our 5-factor analysis considers the best 
scientific information currently available. Our determination in the 
proposed rule was that the best available information does not indicate 
that winter (or summer) recreation is a threat to the DPS. As stated in 
the proposed rule, much of the recreational winter use by humans occurs 
in relatively small areas, like ski areas, that make up only a small 
portion of the large home range of a wolverine, and do not occur at a 
scale that is likely to have a population-level effect. We acknowledge 
that there are a limited number of studies that have evaluated the 
impact of human activities on wolverines (Heinemeyer et al. 2001, 
Heinemeyer and Copeland 1999, Heinemeyer et al. 2012, Pulliainen 1968); 
however, what information is available indicates there is no threat to 
wolverines from recreational activities. This does not mean that new 
scientific information, should it show significant impacts from this 
factor, would be ignored, or that the case is closed and no more 
research is needed. To the contrary, we hope the current research on 
the impacts of recreation on wolverines now taking place will shed 
significant new light on this issue. Until new data indicate otherwise, 
we stand by our assessment that the best available information does not 
indicate that winter recreation is a threat to the DPS.
    (2) Comment: Multiple reviewers and commenters stated that the 
claim in the proposed rule that human-caused mortality is likely 
additive to natural mortality is not well-founded, and that under 
sufficient scrutiny, it is apparent that human-caused mortality is not 
additive in Montana.
    Our Response: Very little is known about wolverine populations in 
the DPS including population size, trends, mortality, or reproductive 
rates. As described in the proposed rule, the population in the DPS is 
thought to be around 250-300, and consists of small, semi-isolated 
subpopulations that likely interact as a metapopulation with some 
connection to the larger population in Canada. It is true that human-
caused mortality has never been demonstrated to be additive or 
compensatory in this area. We agree that, given the small amount of 
human-caused wolverine mortality and the fact that wolverine 
populations are increasing, current levels of mortality are sustainable 
and that human-caused mortality is not currently additive. We have 
changed this conclusion in this document.
    (3) Comment: One peer reviewer stated that the characterization of 
the wolverine niche as ``unproductive'' ignores the fact that 
wolverines are adapted to exploiting their particular environment. A 
niche that is unproductive for most species may be highly productive 
for wolverines.
    Our Response: Overall, the habitats used by wolverine are 
considered unproductive relative to other habitats across the globe. 
However, wolverines are specially adapted to take advantage of the 
resources offered in the habitats they occupy, and so, the niche is 
productive from the wolverine's perspective.
    (4) Comment: One peer reviewer and several commenters thought that 
the proposed rule states that historical densities would have likely 
been higher than today leading to larger historical populations.
    Our Response: In the proposed rule, we meant that the overall 
population would have been larger historically due to the larger area 
occupied by wolverines. We did not mean to suggest that we believed 
that densities would have been higher.
    (5) Comment: One peer reviewer stated that Aubry et al. (2007) did 
not suggest that the habitat in which extralimital records were found 
is unimportant and that we incorrectly relayed this in the proposed 
rule.
    Our Response: We agree with the reviewer that there may be 
important areas for wolverines that contain habitat important for 
behaviors other than residential home range use or reproduction (for 
example, areas of connectivity used for movement between suitable 
habitat patches). However, available information on this topic is 
lacking, and it is not possible to accurately identify these types of 
habitats at this time.
    (6) Comment: One peer reviewer commented that lack of adequate gene 
flow should be considered a major threat to wolverines. The potential 
for human occupation of linkage habitat could adversely affect movement 
of wolverines between habitats, making gene flow a more important issue 
in the future.
    Our Response: We agree that it is possible that lack of sufficient 
connectivity between populations and resultant lack of genetic exchange 
could affect wolverines. However, at this time, the best available 
information does not suggest that lack of adequate gene flow or reduced 
genetic diversity has had negative effects on wolverines in the DPS, as 
is discussed below. Human disturbance in wolverine habitat in the 
contiguous United States has likely resulted in the loss of some minor 
amount of wolverine habitat, but this loss has not yet been quantified. 
Wolverines have been documented to persist and reproduce in areas with 
high levels of human use and disturbance, including developed alpine 
ski areas and areas with motorized use of snowmobiles (Heinenmeyer 
2012, entire), which suggests that that such activities are not likely 
to impede movement of wolverines between habitats. Whether human 
occupation or disturbance reduces wolverine gene flow, and ultimately 
wolverine population or metapopulation persistence, is uncertain at 
this time.
    (7) Comment: Several peer reviewers and commenters thought that 
climate change is likely to have the effect of concentrating human 
activities, like winter recreation, into remaining cold, snowy habitat, 
further increasing the effect of these activities on wolverines.
    Our Response: This scenario, while possible, is speculative. It is 
also possible (but similarly speculative) that winter recreation will 
become less popular as opportunities diminish. However, we have no 
evidence to suggest that winter recreation activities have a negative 
effect on wolverines;, and whether further concentrating recreation 
into smaller areas (should this occur) would affect wolverine 
population and metapopulation persistence is uncertain. These potential 
effects were considered but do not rise to the level of a threat 
because available information does not indicate evidence of such 
effects at this time.
    (8) Comment: One peer reviewer and several commenters stated that a 
population viability analysis would provide better information on which 
to base the listing decision than what is currently relied upon.
    Our Response: While a population viability analysis may be 
desirable, at this point in time, none exists for wolverines in the DPS 
due to a lack of demographic information that would be required to do 
such an analysis. The Act requires that we base the listing decision on 
the best scientific and commercial information available at the time of 
the decision.
    (9) Comment: One peer reviewer and many commenters asserted that 
loss of genetic diversity due to small population size is a threat to 
the DPS regardless of climate change.

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    Our Response: Small population size and reduced genetic diversity 
are potential, though as-yet undocumented, threats to wolverines in the 
contiguous United States. There is some evidence that genetic diversity 
is lower in wolverines in the DPS than it is in the more contiguous 
habitat in Canada and Alaska. The consequence of this lower genetic 
diversity to wolverine conservation is unknown. We do not discount the 
possibility that loss of genetic diversity could be negatively 
affecting wolverines now and continue to do so in the future. It is 
important to point out, however, that wolverine populations in the DPS 
area are thought to be the result of colonization events that have 
occurred since the 1930s. Such recent colonizations by relatively few 
individuals and subsequent population growth are likely to have 
resulted in founder effects, which could contribute to low genetic 
diversity (Schwartz et al. 2007). While we acknowledge that the effect 
of small population size and low genetic diversity may become more 
significant if populations become smaller and more isolated, we lack 
reliable information to conclude if and when this would occur.
    (10) Comment: One peer reviewer stated that the proposed rule 
should not have considered trapping a threat because trapping only 
occurs in Montana, and to be considered a threat, an activity must 
occur across the entire range of the DPS.
    Our Response: In a listing analysis, we consider all potential 
threats regardless of the extent of their occurrence to make a 
determination as to whether all of the threats, when considered 
individually or cumulatively, indicate that the DPS meets the 
definition of an endangered or threatened species under the Act. 
Therefore, threats that occur in only a portion of the range of the DPS 
may affect the conservation status of the whole, or affect a 
substantial enough portion of the whole so that the future of all or a 
significant portion of the range of the DPS is at risk.
    (11) Comment: The conclusion that females are unlikely to move into 
the southern Rocky Mountains on their own is speculative.
    Our Response: Although most studies document greater dispersal 
distances for males than females (Hornocker and Hash 1981, p. 1298; 
Banci 1994, pp. 117-118; Copeland and Yates 2006, Figure 9; Moriarty et 
al. 2009, entire; Inman et al. 2009, pp. 22-28; Brian 2010, p. 3;), 
Vangen et al. (2001, p. 1644) found that both males and females are 
capable of long-distance dispersal. They documented female dispersal 
distances of up to 178 km in one case, with average dispersal distance 
(60  48 km) not significantly different from males (51 
 30 km). Given this scientific evidence, we believe it is 
possible that females could move into the southern Rocky Mountains 
without human facilitation.
    (12) Comment: One peer reviewer commented that the proposed rule 
indicates that we have strong information about where wolverine dens 
occur in Idaho and Montana. This may lead the reader to believe that 
all potential denning areas are known. This is not the case.
    Our Response: We agree with the reviewer that we do not know where 
all potential wolverine dens are located. Dens may occur outside of the 
conditions described in the proposed rule. Although the proposed rule 
provided an accurate summary of the existing scientific information 
pertaining to documented den sites in Idaho and Montana, we did not 
mean to imply that all potential denning sites are known.
    (13) Comment: One peer reviewer noted that, in the proposed rule, 
we indicate that the elevations used by wolverines that once inhabited 
the Sierra Nevada Range are unknown. In fact, we do have reliable 
information that is compiled in Aubry et al. 2007.
    Our Response: While we agree that the account of location data in 
Aubry et al. (2007) provides some information on wolverine use of the 
Sierra Nevada Range, the information contained in that report is not 
comparable to habitat use information from radio-telemetry studies used 
elsewhere in the proposed rule, where we reported highly credible 
elevation information (Copeland 1996, p. 94; Magoun and Copeland 1998, 
pp. 1315-1316; Inman et al. 2007c, p. 71). The information reported in 
Aubry et al. (2007) represents opportunistically collected wolverine 
encounters and trapping information, which are likely biased by factors 
that affect the probability of humans detecting wolverines. These 
biases include the confounding factor of human use and baiting of 
traps, which could cause wolverines to venture into habitats they 
otherwise seldom use. These potential biases led us to conclude that 
the elevation data for California compiled by Aubry et al. (2007) are 
not reliable for drawing conclusions regarding wolverine habitat use in 
the Sierra Nevada at any but the grossest of scales.
    (14) Comment: One peer reviewer stated that the proposed rule was 
premature in concluding that the Great Lakes and Northeast regions do 
not support a wolverine population now, and likely did not support 
wolverine populations historically. This conclusion is not well 
supported by the available information, which shows a relatively 
consistent historical record for the early post-settlement period for 
the Great Lakes and a sparser record for the Northeast.
    Our Response: Our conclusion that the Great Lakes area was not 
historically wolverine habitat was based on a review of historical 
occurrence records for wolverines in this area. We agree that the 
conclusion about historical populations was premature, and that this 
area may have supported wolverine populations prior to and into the 
settlement period. We continue to conclude that the Northeast was 
unlikely to have supported wolverines historically, but agree that the 
evidence is not definitive.
    (15) Comment: One peer reviewer asserted that the proposed rule 
erred by stating that wolverines are habitat generalists. Wolverines 
require very specific habitat conditions and are correctly considered 
habitat specialists.
    Our Response: Wolverine habitat in the contiguous U.S. appears to 
consist of disjunt patches of rugged, high alpine areas with with a mix 
of tree cover, alpine meadow boulders, avalanche chutes, and patches of 
spring snow (Copeland et al.2010, entire; Inman et al. 2012, p.785; 
Inman et al. 2013, p. 283). We agree that they could be considered 
habitat specialists.
    (16) Comment: One peer reviewer noted that the proposed rule 
indicates that the wolverine found in the Sierra Nevada Range of 
California in 2008 was from Idaho based on genetic information. The 
genetics of that individual were not diagnostic of Idaho, and could in 
fact have come from other portions of the wolverine range.
    Our Response: Moriarty et al. (2009, entire) used mitochondrial and 
microsatellite genetic evidence, as well as stable isotope analysis, to 
verify the wolverine's origin. That analysis placed the California 
wolverine into a group primarily comprised of individuals from the 
Sawtooth Mountains of Idaho with a confidence level of 73.4 percent.
    (17) Comment: Several peer reviewers and commenters were confused 
by our use of wolverine science from Scandinavia or were unsure when 
our conclusions were based on Scandinavian data.
    Our Response: We have attempted to clarify when referring to data 
collected in Scandinavia. In many cases when we do not have data from 
North America, we found Scandinavian wolverine data are the best 
available information regarding general wolverine biology,

[[Page 47526]]

where behavior is consistent regardless of geographic region.
    (18) Comment: One peer reviewer commented that there are historical 
wolverine records from New Mexico, and this should be noted in the 
rule.
    Our Response: The potential for wolverine presence in New Mexico is 
confounded by a sparse historical record that may not accurately 
reflect wolverine distribution. One 19th century record from New 
Mexico--without precise locality information--was reported in Aubry et 
al. (2007). The lack of precise location data in this area so close to 
Colorado and its known historical (pre-1930) wolverine population 
leaves open the possibility that the animal in question was actually 
from the mountains of adjacent Colorado. Habitat in the Sangre de 
Cristo Mountains of northern New Mexico is contiguous with habitat in 
Colorado that contained verifiable historical wolverine records. Based 
on this evidence of contiguous habitat and a documented record, it is 
likely (though uncertain) that wolverines in the southern Rocky 
Mountains occurred in adjacent contiguous habitat in New Mexico's 
Sangre de Cristo Mountains and possibly other mountain ranges in 
northern New Mexico. It is not known whether wolverines in this area, 
if present, would have been established as an extension of the southern 
Rocky Mountain population, or rather might have been occasional 
migrants to the area.
    (19) Comment: One peer reviewer commented that the proposed rule 
determined that the DPS is discrete based on the international boundary 
between the United States and Canada. The reviewer suggested that the 
Service could also conclude the DPS is discrete based on differences in 
genetics between the populations in Canada and the United States.
    Our Response: As described in our December 14, 2010, 12-month 
petition finding (75 FR 78030) and our February 4, 2013, proposed rule 
to list the DPS (78 FR 7864), to be considered discrete under our DPS 
Policy, a population of a vertebrate species needs to satisfy either of 
two conditions: (1) It is markedly separated from other populations of 
the same taxon as a consequence of physical, physiological, ecological, 
or behavioral factors (measures of genetic or morphological 
discontinuity may provide evidence of this separation); or (2) it is 
delimited by international governmental boundaries, across which 
differences in control of exploitation, management of habitat, 
conservation status, or regulatory mechanisms exist. Having found that 
the population was discrete based on the differences in control of 
exploitation and conservation status across the international boundary, 
an evaluation of possible genetic discontinuity was not necessary, as 
only one of the conditions need be met to satisfy the discreteness 
criterion.
    (20) Comment: One peer reviewer and several commenters said that 
climate changes to ecosystems can cause counter-intuitive movement of 
climatic conditions, resulting in changes that are difficult to 
predict. For example, in the proposed rule it states that wolverine 
habitat is likely to migrate northward and up mountain slopes as 
climate changes progress, but this result is not necessarily the case.
    Our Response: We agree that there is considerable uncertainty in 
how climate change will affect wolverine habitat and population 
persistence. Climate modelling has been done at broad ecological 
scales, and we do not know how fine-scale changes in snow patterns may 
affect population viability. There are a variety of fine-scale local 
factors that determine where wolverines den, the quality of den sites, 
and how wolverines use the landscape. As is discussed further below, we 
lack a clear understanding of how changes in snowfall will affect 
wolverine habitat quality and ultimately population viability and 
persistence, and that is reflected in the text of this document.
    (21) Comment: Two peer reviewers and multiple commenters stated 
that the proposed rule relies almost entirely on the Copeland et al. 
(2010) bioclimatic envelope model as a prediction of suitable habitat. 
This hypothesis is not based on sound theory.
    Our Response: While Copeland et al. (2010) portrays a strong 
argument for wolverine reliance on spring snow cover, their modeling 
did not consider other factors such as land cover, topography, and 
human footprint that have been considered in the analyses by Inman et 
al. (2013) and Fisher et al. (2013). Further, Copeland himself 
(November 26, 2013; p. 2) stated his belief that there are other 
factors beyond snow that influence wolverine distribution. We have 
reflected these concerns in the text of this document.
    (22) Comment: One peer reviewer commented that the model in 
Copeland et al. (2010) overestimates the habitat used for wolverine 
denning by approximately 75 percent. This means that up to 75 percent 
of that modeled habitat could be lost to climate change impacts without 
affecting wolverine populations. Therefore, the predicted impacts of 
the McKelvey et al. (2011) analysis are not likely to occur.
    Our Response: It is unclear how much habitat wolverines need for 
denning purposes. However, den sites do not appear to be limited at 
this time. Available information suggests it is possible that changes 
in climate may affect availability of deep snow for den sites, but the 
specific response or sensitivity of wolverines to these forecasted 
changes is uncertain at this time.
    (23) Comment: Two peer reviewers asserted that effective population 
estimates cited in the proposed rule from Schwartz et al. (2009) did 
not include sampling from portions of the range of the DPS. This lack 
of sampling the entire DPS area may have biased the estimated effective 
population size low.
    Our Response: The reasons for excluding areas from the sample are 
covered in Schwartz et al. (2009) and have to do with reducing the 
effects of population substructure in the effective population size 
estimate. Essentially, when making this type of calculation, one 
attempts to sample those animals that are part of an interbreeding 
population. It is not desirable to include adjacent populations that 
may be semi-isolated, as this would bias the results. The purpose of 
estimating genetically effective population size is not to produce a 
population estimate, but to use the effective population size estimate 
as a tool to make inferences about the potential for the maintenance of 
genetic diversity. In that light, it is appropriate to sample only from 
areas that are thought to form cohesive populations. The estimate 
provided for the northern Rocky Mountains populations was low, and 
represents the effective population size for that area. This result is 
important to the listing decision because the northern Rocky Mountains 
portion of the DPS is thought to be the largest subpopulation in the 
DPS and is physically connected to Canada. Therefore, we expect that 
the northern Rocky Mountains would have the subpopulation that is most 
genetically resilient of the current subpopulations in the DPS.
    (24) Comment: One peer reviewer commented that the bioclimatic 
envelope model in Copeland et al. (2010) does not encompass all habitat 
and all dens used by wolverines, and so is invalid.
    Our Response: Copeland et al. (2010) acknowledge that information 
on wolverine historical range in Europe and Asia is lacking and the 
``Methods'' section of their paper describes the timeframe and other 
criteria used as a basis for the habitat and den site information used 
in their modeling. Models typically do not encomass all

[[Page 47527]]

habitat and reproductive areas used by the particular species being 
assessed. The validity of models and their outcomes does not require 
that they encompass all habitat and all reproductive areas of a 
species. While we find that the model does provide valuable information 
on the correlation between wolverine and snow cover, we acknowledge 
that there are limitations.
    (25) Comment: Two peer reviewers and several commenters stated that 
central to acceptance of the Copeland et al. (2010) snow model and the 
subsequent use of the snow model in McKelvey et al. (2011) for 
predicting future wolverine habitat in the western States, one must 
accept that wolverine denning extends to May 15 and that continuous 
snow cover is required until then in the western States.
    Our Response: The habitat described in the Copeland model includes 
areas that retained snow until May 15, in as few as 1 of 7 years. In 
other words, if an area retained snow in only 1 of 7 years, it was 
still included in the model describing habitat, and 97.9 percent of the 
sample of den sites fell within this area. That means that some 
proportion of those den sites fell within an area that did not retain 
snow each year. We acknowledge that den abandonment often occurs 
earlier than May 15. Abandonment varies from March to May, with earlier 
timing associated with den sites in Idaho, and later abandonment 
documented in Alaska and Norway (Myrberget 1968, pp. 112-114; Magoun 
and Copeland 1998, pp. 1316-1317). However, 95 percent of summer and 86 
percent of winter telemetry locations were concordant with spring snow 
coverage. It is important to note that factors beyond spring snow 
persistence were not considered in the model; therefore, the model may 
not present a complete picture of factors that influence wolverine 
distribution.
    (26) Comment: Two peer reviewers and several commenters thought 
that the results in Copeland et al. (2010) are biased by the fact that 
most known wolverine dens occur in mountainous habitats. This is an 
artifact of where people have searched for wolverine dens rather than 
where most dens occur. If more searching had been done in lowland 
boreal habitats, the fit of the Copeland et al. (2010) model would not 
have been as good.
    Our Response: It may be true that if more dens had been discovered 
in flat or lowland boreal forest areas that the fit of the model would 
have been worse. This is explained by the authors of Copeland et al. 
(2010) as an artifact of the remote sensing data used in the analysis. 
Heavily canopied habitats, such as lowland boreal forests, hide snow 
beneath canopy cover, and the snow may be missed by satellites. This 
problem is largely irrelevant to the listing determination, however, 
because the habitats in the contiguous U.S. DPS are not lowland boreal 
habitats but rather mountainous habitats where the model fit is very 
good.
    (27) Comment: Two peer reviewers and several commenters said that 
the analysis in Copeland et al. (2010) is invalid as an estimate of 
wolverine habitat. McKelvey et al. (2011) relies on Copeland et al. for 
input data, and so is also invalid as an estimate of the potential 
impacts of climate change on wolverine habitat.
    Our Response: Copeland et al. (2010) portrays a strong argument for 
wolverine reliance on spring snow cover; however, as discussed under 
Factor A, the analysis did not consider factors beyond snow that may 
influence wolverine habitat. Therefore, we believe that while Copeland 
et al. (2010) represents the best available information, the model 
outcome may not provide a complete picture of available habitat. In 
their climate change modeling, McKelvey et al. (2011) relied on 
conclusions in Copeland et al. (2010), that wolverine habitat is 
closely tied to persistent spring snow cover. Given the uncertainties 
in Copeland et al.'s (2010) bioclimatic envelope model, predictions of 
wolverine habitat under climate change in McKelvey et al. (2011) may 
also not be accurate.
    (28) Comment: Two peer reviewers stated that the limitations of 
Moderate Resolution Imaging Spectroradiometer (MODIS)-based snow cover 
models should be recognized and taken into consideration when 
evaluating the accuracy of snow model predictions. For example, 
McKelvey et al. (2011) recognized that there are issues with the scale 
at which the MODIS data can be applied.
    Our Response: We agree that there are limitations inherent in 
downscaled climate models and that it is important to understand the 
effect of climate-data spatial resolution on wolverine viability in 
complex terrain. Downscaling techniques improve understanding of 
climate at smaller, regional scales compared to Global Climate Models, 
but their spatial resolution is still inadequate to describe the 
variability of microclimates in which organisms live (Potter et al. 
2013, p. 2935). Franklin et al. (2012, pp. 478-482) show that there can 
be large differences between suitable habitats predicted from coarse 
versus fine-scale climate models, and concluded that, on average, a 
scale approximately twice as fine as that used in McKelvey et al. 
(2011, entire) (280 m vs. 500 m) is adequate, and that in rugged 
terrain (such as that used by wolverines), even finer models (e.g., 10 
to 30 m) may be needed to represent significant microclimates. McKelvey 
et al. (2011, p. 2895) reached similar conclusions about their own 
modeling efforts: ``although wolverine distribution is closely tied to 
persistent spring snow cover (Copeland et al. 2010), we do not know how 
fine scale changes in snow patterns within wolverine home range may 
affect population persistence.'' We concur; an improved understanding 
of how microclimatic variation alters the habitat associations of 
wolverines at fine spatial scales is needed. Ultimately, our final 
listing decision for the wolverine rested on the question of whether we 
can reliably predict how the effects of changes in climate on habitat 
may affect population persistence in the DPS; therefore, this 
limitation of the model was of critical importance in our reevaluation 
of the proposed rule.

Comments From States, Agencies, and the Public

    (29) Comment: There is not enough information known about the 
wolverine population, such as size, demographics, distribution, and 
trend, on which to base a listing rule.
    Our Response: We are required to use the best available scientific 
and commercial information when listing a species under the Act. 
Published findings on wolverine populations and their genetic structure 
has been available for many years, although we acknowledge that 
information on wolverine numbers, population trends, and potential 
effects of loss of genetic diversity is limited. Our analysis included 
a thorough consideration of all available literature, peer review, 
public comment, and results of a scientific panel (Service 2014, 
entire). Based on our analysis, through this document, we withdraw the 
proposed rule to list the DPS of the North American wolverine occurring 
in the contiguous United States as a threatened species under the Act 
(78 FR 7864; February 4, 2013), as well as our associated proposed rule 
under section 4(d) of the Act contained in the proposed listing rule 
(78 FR 7864; February 4, 2013) and the proposed nonessential 
experimental population designation for the southern Rocky Mountains 
(78 FR 7890; February 4, 2013).
    (30) Comment: Several commenters stated that the global climate 
models used to predict habitat impacts of climate change are not 
precise enough to be useful for that purpose.

[[Page 47528]]

    Our Response: We have carefully reexamined all of the best 
available scientific data used in our proposed rule, and any 
information that has became available through the review process since 
the publication of the proposed rule. As explained in detail in this 
document, we concluded that the analyses in McKelvey et al. (2011) and 
other sources were not conducted at a fine enough scale to serve as the 
basis for having sufficient certainty about how climate change may 
impact wolverine habitat in the future. In addition, we have recognized 
substantial uncertainty exists regarding projections of future snowfall 
amounts and persistence in areas most important for crucial wolverine 
life stages (i.e., denning), and as well as the possible response of 
the DPS to effects of climate change in the future.
    (31) Comment: There are alternative hypotheses to explain the 
distribution of wolverines that should be explored further.
    Our Response: We agree that it is important to consider all 
potential factors that may constrain wolverine distribution. The 
Copeland et al. (2010) model focused on one hypothesis, spring snow 
persistence, to explain wolverine distribution. The model did not 
consider other factors such as land cover, topography, and the human 
footprint that appear to also influence primary wolverine habitat use 
(Inman et al. 2013; Fisher et al. 2013). Copeland himself (November 26, 
2013; p. 2) stated his belief that there are other factors beyond snow 
that influence wolverine distribution. These considerations were part 
of the basis for our decision to withdraw the listing rule.
    (32) Comment: One commenter questioned the evidence for the 
assumption in the proposed rule that predation is part of the reason 
for wolverines denning in deep snow.
    Our Response: Predation as an explanation for wolverines denning in 
deep snow has been suggested by several wolverine experts, including 
Magoun and Copeland (1998), Copeland et al. (2010), and Inman et al. 
(2012, p. 638).Wolverine kits are vulnerable to predation by other 
wolverines and other predators while they are in the den (Persson et 
al. 2003, p. 24). Female wolverines often dig elaborate snow tunnels 
down to ground-level substructure, such as boulders or avalanche 
debris, to birth and raise kits. A reasonable explanation as to why 
they go to this effort is that kits need security from predators that 
such snow tunnels provide.
    (33) Comment: Several commenters asserted that the proposed rule 
relies on inadequate science regarding genetic connectivity and 
effective population sizes in wolverines. They also claim that the 
proposed rule is inconsistent in applying genetic information to 
designating the DPS and the discussion of effective population size.
    Our Response: We are required to use the best available scientific 
and commercial information when determining whether to list a species 
under the Act. We have found in this determination that genetic factors 
are not a threat to the DPS due to increasing populations. Although we 
did not use the lack of genetic contiguity between Canada and the 
United States wolverine population as justification for the DPS, we do 
recognize the apparent lack of gene flow across the international 
boundary.
    (34) Comment: Several commenters said that because wolverines have 
persisted through past climate changes that were severe, they will 
persist through future changes as well.
    Our Response: While we acknowledge that the wolverine and other 
species have persisted through past changes in climate, it does not 
automatically follow that the wolverine or other species will persist 
through future changes since the conditions concerning the status of 
the species, its habitat, and other relevant factors and their 
responses to such changes are unlikely to be identical to what was 
present in the past. In our analysis of the best available data 
concerning the wolverine DPS, there is significant evidence that the 
climate within the larger range of the wolverine is warming, affecting 
snow patterns and associated wolverine habitat. However, as described 
in this document, we currently have a relatively high degree of 
uncertainty about the likely response of wolverines to future changes.
    (35) Comment: The Service should monitor wolverine populations and 
habitat to determine if climate change impacts actually occur before 
pursuing a listing based on a speculative threat.
    Our Response: The Act requires that we make a listing determination 
based on the best scientific and commercial data available at the time 
of our decision. When evaluating population trends or the impacts of a 
particular threat, we must rely on the best available science, rather 
than speculation, to assess the future status of a species and to 
determine whether it meets the definition of an endangered or 
threatened species. As explained above, we have determined that the 
best available information suggests that climate change may affect 
habitats used by wolverines; however, the specific response or 
sensitivity of wolverines to these current and forecasted changes is 
uncertain at this time.
    (36) Comment: Management of wolverines is similar in Canada and the 
United States. There is no reason to conclude that wolverines in these 
areas are discrete based on differences in management.
    Our Response: Wolverines are managed by regulated harvest 
throughout western Canada and Alaska; in the lower 48 U.S. States, 
regulated wolverine harvest occurs only in Montana, and at a very low 
level (average harvest = 3.25 wolverines/year; Montana Department of 
Fish Wildlife and Parks 2010, pp. 8-11). In November 2012, a district 
court issued a restraining order blocking the opening of Montana's 
trapping season on wolverine; the season remains closed (Case No. BDV-
2012-868). Thus, we conclude there are differences in management across 
the international boundary. Please refer to our December 14, 2010, 12-
month petition finding (75 FR 78030) and our February 4, 2013, proposed 
rule to list the DPS (78 FR 7864) for a more robust discussion of our 
analysis of wolverine in the contiguous United States and our DPS 
Policy. However, as described in this document, we have concluded that 
this DPS does not warrant listing, and we are withdrawing our February 
4, 2013, proposed rule to list the DPS of the North American wolverine 
occurring in the contiguous United States as a threatened species under 
the Act (78 FR 7864; February 4, 2013), as well as our associated 
proposed rule under section 4(d) of the Act contained in the proposed 
listing rule (78 FR 7864; February 4, 2013) and the proposed 
nonessential population designation for the southern Rocky Mountains 
(78 FR 7890; February 4, 2013).
    (37) Comment: Several commenters noted that regulatory mechanisms 
to combat climate change do not exist; therefore, it is not appropriate 
to use this threat to justify a listing.
    Our Response: Under the Act, regardless of whether regulatory 
mechanisms exist to address a particular threat, we cannot ignore that 
threat if it contributes to the basis for a determination that the 
species meets the Act's definition of an endangered or threatened 
species. As a hypothetical example, if a severe disease is placing a 
species at high risk of extinction and no regulatory mechanisms exist 
to combat the disease, we would not ignore the disease as part of the 
basis for a listing determination. Also, with regard to climate change, 
we consider the ongoing and reasonably likely effects of such changes 
and how those

[[Page 47529]]

effects relate to the status of a species; we do not make listing 
determinations based on climate change per se. For example, our 
decision to list the polar bear was based on the likely loss of sea ice 
habitat and related impacts to polar bears. While it may seem like a 
fine point that we focus on the effects of changes in climate rather 
than climate change per se, it is an important distinction. With regard 
to the wolverine DPS, we have determined that potential habitat impacts 
due to climate change are not a threat to the DPS such that the species 
meets the definition of an endangered or threatened species under the 
Act at this time. Therefore, an analysis of the existing regulatory 
mechanisms that address the effects of climate change is not necessary 
in this case.
    (38) Comment: Multiple commenters noted that there are several 
datasets available that Copeland et al. (2010) did not consider and 
that including those in the analysis would likely change the outcome of 
our proposed rule.
    Our Response: We acknowledge that some available datasets were left 
out of the Copeland et al. (2010) model. The authors also acknowledge 
that information on wolverine historical range in Europe and Asia is 
lacking. While we believe the model does provide valuable information 
on the correlation between wolverine and snow cover, these omissions 
limit the ability to provide a complete picture of available wolverine 
habitat. We incorporated a discussion of these limitations of the 
dataset into the text of this document.
    (39) Comment: Several States commented that the analysis in 
Copeland et al. (2010) excluded data from wolverines in the far north 
for their year-round analysis of habitat use relative to their snow 
model. If they had included these animals from places where persistent 
spring snow was ubiquitous they would have found that they did not 
select for snow.
    Our Response: The Copeland et al. (2010) paper addressed this 
issue, saying that in areas of the far north in arctic and sub-arctic 
conditions, wolverines are able to use the entire landscape and that 
therefore their model loses effectiveness for predicting wolverine 
habitat use. This is not an issue in the contiguous U.S., where 
wolverine habitat occurs at high elevations in temperate mountains. In 
these areas, the correlation between the bioclimatic envelope and 
wolverine habitat use and denning is quite close.
    (40) Comment: Several States and commenters asserted that 
wolverines do not need deep snow until May 15 for thermal buffering 
because temperatures have moderated by then.
    Our Response: We agree. We do not know exactly what the causal 
relationship is between spring snow and wolverine dens. Thermal 
buffering is a hypothesis, but has not yet been tested. Additionally, 
as mentioned above, the timing of den abandonment varies geographically 
and seems to coincide with spring thaw. Wolverines in Idaho appear to 
abandon den sites earlier (March-April) than in other areas studied, 
including Alaska and Norway (late April-early May). It appears possible 
that wolverines in the DPS area do not need snow until May 15.
    (41) Comment: One State commented that climate change may benefit 
wolverines due to increased productivity in their habitats.
    Our Response: Although this hypothesis could possibly be true, the 
best available information does not support or refute this hypothesis. 
Our withdrawal of the proposed listing rule is based upon the lack of 
information concerning the likely biological response of wolverines to 
the effects of climate change. We do not assert that wolverines are 
likely to benefit from climate change or its effects on habitat.
    (42) Comment: Several States commented that wolverines have 
expanded their populations in the DPS over the last 100 years. 
Simultaneous to this expansion, climate warming has also been reducing 
snowpack in the DPS. This is inconsistent with the hypothesis that 
persistent spring snow is important to wolverines or that changes in 
persistent spring snow in the future are likely to adversely affect 
wolverines.
    Our Response: Wolverines were likely extirpated from the entire 
contiguous United States in the first half of the 20th century due to 
unregulated trapping and predator control; populations have since 
recolonized from Canada and are currently expanding within the DPS area 
(refer to the on February 4, 2013 proposed rule at 78 FR 7864 for a 
more robust discussion of wolverine population status and 
distribution). We believe this recolonization and expansion is 
primarily due to changes in harvest and predator control practices. The 
best available information does not indicate that climate change 
effects have caused contraction of wolverine habitat in the DPS area at 
this time, and consequently wolverine growth and expansion has not 
ceased. It is likely that climate change will impact snowfall and snow 
persistence in the future, but we have no reliable information to 
suggest how wolverines in the DPS will respond to these changes.
    (43) Comment: One State disagreed with our determination in the 
proposed rule that wolverine genetic variation is low, or lower than 
historical levels, in the northern Rocky Mountain wolverine population.
    Our Response: Available evidence indicates that genetic diversity 
among wolverines in the DPS is lower than it is in the founding 
population in Canada (Schwartz et al. 2009, p. 3229). Wolverines in the 
contiguous United States are thought to be derived from a recent 
recolonization event after they were extirpated from the area in the 
early 20th century (Aubry et al. 2007, Table 1). Consequently, 
wolverine populations in the contiguous United States have reduced 
genetic diversity relative to larger Canadian populations as a result 
of founder effects or inbreeding (Schwartz et al. 2009, pp. 3228-3230). 
Such a result is not unexpected following recolonization by relatively 
few individuals and subsequent population growth. Whether the DPS may 
be suffering any negative effects as a consequence of lower genetic 
diversity in comparison to the Canadian population is unknown. While we 
acknowledge that the effect of small population size and low genetic 
diversity may become more significant if populations become smaller and 
more isolated, we are uncertain if and when this response might occur.
    (44) Comment: Several States commented that there is insufficient 
evidence to conclude that there is a genetic break between the DPS and 
Canadian populations. Insufficient sampling in the area near the 
international boundary means that the precise location of any break 
that may exist is in question.
    Our Response: We reviewed the best available information on this 
subject. States did not provide additional citations. The analysis in 
Schwartz et al. (2009) provided evidence that there is a lack of 
genetic connectivity between wolverine populations in the area near the 
international boundary. The reason for the apparent lack of 
connectivity is not known. The authors speculated that it may be 
related to heavy trapping pressure on the Canadian side of the 
boundary, but this hypothesis remains untested.
    (45) Comment: Several commenters stated that hunting and trapping 
of species that prey on wolverines would benefit the DPS.
    Our Response: It is possible that hunting and trapping benefit 
wolverines by reducing populations of predators that may occasionally 
kill wolverines.

[[Page 47530]]

The magnitude of this potential benefit, if it exists, is unknown.
    (46) Comment: Multiple commenters and States thought that the 
listing proposal essentially dismissed habitat impacts resulting from 
land management decisions.
    Our Response: The Service recognized and acknowledged the effects 
of land management activities, as well as recreation, infrastructure, 
and development, on the wolverine DPS. However, as we stated in the 
proposed listing rule, the scale at which these activities occur is 
relatively small compared to the average size of a wolverine's home 
range. For that reason, we concluded that land management decisions do 
not substantially impact the wolverine. After reviewing the best 
available information, we stand by this assessment.
    (47) Comment: One commenter believed the wolverine does not qualify 
as a DPS because the population is not discrete, and loss of the 
subspecies in the contiguous United States would not represent a 
significant gap in relation to its entire range, which includes areas 
within the contiguous United States, Canada, and Alaska. The population 
and habitat area in the lower 48 States represent a small fraction of 
the entire range; meaning that, for the purposes of the Act, the 
wolverine is insignificant when compared to the entire North American 
subspecies.
    Our Response: Please refer to our December 14, 2010, 12-month 
petition finding (75 FR 78030) and our February 4, 2013, proposed rule 
to list the North American wolverine (78 FR 7864) for a more robust 
discussion of our analysis of the wolverine in the contiguous United 
States and our DPS policy. We recognize that there may be differences 
of opinion on the definition of ``significant.'' However, for the 
reasons detailed in the February 4, 2013, proposed rule, we conclude 
both that the contiguous U.S. population of the wolverine is discrete 
and that the loss of that population would result a significant gap in 
the range of the taxon, in accordance with our DPS policy. However, as 
described in this document, we have concluded that this DPS does not 
warrant listing, and we are withdrawing our proposed rule to list the 
DPS.
    (48) Comment: Several States commented that the determination that 
the wolverine population in the contiguous United States is discrete is 
arbitrary and without merit because the only regulatory mechanism that 
the Service concludes is lacking is one that exists internationally, 
that is, the current inability to regulate climate change. Otherwise, 
the regulatory mechanisms currently in place in the lower 48 U.S. 
States have been deemed by the Service to be adequate.
    Our Response: Please refer to our December 14, 2010, 12-month 
petition finding (75 FR 78030) and our February 4, 2013, proposed rule 
to list the North American wolverine (78 FR 7864) for a detailed 
evaluation of the discreteness criterion for the contiguous U.S. 
population of the wolverine under our DPS policy. In accordance with 
that policy, we concluded that this population is discrete based on 
differences in control of exploitation and conservation status of the 
wolverine across the border between Canada and the United States.
    (49) Comment: Many States and public commenters stated that instead 
of future predictions of threats, Service should rely on current 
population status.
    Our Response: Listing decisions under the Act require that we 
synthesize current status with threat projections in the future to 
determine if the species is presently in danger of extinction 
(endangered) or is likely to become endangered in the foreseeable 
future (threatened). Following these statutory definitions, it follows 
that although an evaluation of current population status may be 
sufficiently informative as to whether a species meets the definition 
of endangered under the Act, an evaluation of whether a species may be 
threatened necessarily invokes additional mechanisms that allow us to 
project future scenarios for the species based on scientific data, to 
reasonably forecast the conservation status of the species within the 
foreseeable future.
    (50) Comment: Several commenters said that the threat of poisoning 
from 1080 or M-44s should be thoroughly explored in the rule and a 
prohibition on incidental take from poisoning should be instituted.
    Our Response: Wolverines in the contiguous United States were 
likely severely affected by predator poisoning campaigns of the early 
20th century. Those types of widespread, indiscriminant, government-
instituted campaigns intending to eliminate predators from the 
landscape no longer occur within the range of wolverines. Remaining 
predator control efforts are targeted and geographically constrained so 
as to target control where predators are particularly problematic for 
stock growers and to minimize potential poisoning of non-target 
species. There is no evidence that wolverine populations are currently 
being affected by poisoning from 1080 or M-44s. Therefore, the best 
available information does not indicate that poisoning is a threat to 
the DPS.
    (51) Comment: Several commenters suggested that current wolverine 
population densities and population levels are far below historical 
densities and populations. Some also said that the Service should not 
speculate as to historical population numbers or densities.
    Our Response: There is no reliable estimate for wolverine densities 
historically or presently. Current wolverine densities are naturally 
low in areas with wolverine populations, and near zero in areas that 
have not been recolonized by populations such as the southern Rocky 
Mountains and Sierra Nevada Range. Wolverine densities are always 
naturally low relative to most other species due to their need for 
large territories and their tendency to defend those territories from 
other wolverines. Listing under the Act is predicated not on population 
densities and size, but rather on whether the species (here DPS) meets 
the definition of endangered or threatened 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.
    (52) Comment: Several commenters said that mortality from collision 
with vehicles on roads is a threat.
    Our Response: Wolverine mortality from collisions with vehicles has 
occurred in the contiguous United States, but at low levels. Wolverines 
use habitats that are not particulary conducive to roads or 
transportation corridors. Consequently, wolverines usually do not come 
into contact with high-traffic volume roads except in those areas where 
highways cross over mountain ranges, usually major passes. There have 
been recorded instances of wolverines being killed on roads in valleys 
between mountain ranges. These are likely the result of dispersal 
attempts by wolverines and appear to be rare occurrences. There is no 
evidence that this low level of effect is significant to the status of 
the DPS.
    (53) Comment: One commenter stated that the Service should analyze 
the effects of trapping on wolverine habitat and that trapping itself 
modifies or destroys habitat.
    Our Response: We cannot conclude that trapping modifies or destroys 
habitat. Trapping is a mortality factor but generally does not affect 
the ability

[[Page 47531]]

of habitat to provide the life-history requirements of wolverines, such 
as food and shelter. The habitat and its ability to support wolverines 
remains, but the animal is removed if it is trapped. The important 
point is not under what category a threat factor is considered, but 
that the effects of the threat factor are considered. The best 
available information does not indicate that impacts from trapping 
modify or destroy wolverine habitat.
    (54) Comment: Several commenters said that we erred in the proposed 
listing rule by concluding that wilderness designation provides 
protection to wolverines from trapping. They said that trapping is 
allowed in wilderness areas, so they do not provide protection.
    Our Response: Wilderness designations provide refuge from trapping 
by making access to wolverine habitat by trappers more difficult. 
Wolverine habitats tend to have very deep snow and cold temperatures 
during the trapping season. Most trappers access wolverines by 
motorized (snowmobile) transport. Motorized transport is prohibited in 
wilderness areas. This reduces, but may not eliminate, trapping in 
these areas, providing significant protection.
    (55) Comment: One commenter wanted more explanation of why we 
concluded in the proposed rule that trapping was not a threat over most 
of the DPS.
    Our Response: Targeted trapping of wolverines only occurs in 
Montana, and occurs at a low level that is compatible with the current 
population level. Montana is only a part of the DPS. Therefore, 
trapping is not a threat to the entire DPS.
    (56) Comment: One commenter disagreed with our statement in the 
proposed rule that Montana has stopped trapping in isolated mountain 
ranges.
    Our Response: The statement in the proposed rule is accurate as 
written. Montana has removed wolverine trapping from isolated mountain 
ranges in western Montana. The ranges cited in the comments are not 
isolated, but are located adjacent to other wolverine habitats.
    (57) Comment: One commenter said that in contrast to the 2010 12-
month petition finding, the proposed rule discusses the possible 
impacts of human activities very little. The proposed rule also 
suggests that research indicates that there is no effect of human 
activities, rather than that there is very little research on this 
factor.
    Our Response: In the proposed listing rule (78 FR 7864; February 4, 
2013), we reviewed the information, and consolidated the discussion of 
human activities because the lengthy discussion in the 12-month 
petition finding (75 FR 78030; December 14, 2010) did not conclude that 
there were significant threats from those activities. The proposed rule 
concluded that the best available scientific information does not 
indicate that a threat to the DPS currently exists from the impacts of 
human activities.
    (58) Comment: Several commenters suggested that changes to snow 
structure caused by freeze/thaws that create hard surface on snow could 
increase competition or predation on wolverines by other carnivores.
    Our Response: The commenters did not provide any citations with 
their comments. We have no information indicating whether such changes 
in snow structure are causing impacts to the wolverine.
    (59) Comment: One commenter thought that the statement from the 
proposed rule that the current population levels in the contiguous 
United States may not be lower than those in the past is also 
incongruous with population densities in western Canada, where the 
population is vastly higher (15,000 to 19,000 individuals) than in the 
contiguous United States (USFWS 2013, p. 7869), despite being a 
slightly larger yet comparably-sized region.
    Our Response: The reported numbers from Canada and Alaska are not 
population densities; they are population estimates. Densities are 
population per unit of area. The population densities for currently 
occupied areas in the DPS are not measurably different from those in 
adjacent Canada. Despite the two regions being roughly comparable in 
size, the DPS has much less wolverine habitat than Canada and Alaska, 
and the habitat that does exist occurs in semi-isolated patches at high 
elevations, whereas habitat in Canada and Alaska is much more extensive 
and well connected. This explains the difference in wolverine 
population numbers between the two areas historically.
    (60) Comment: Several commenters said that other risk factors not 
considered threats should be considered cumulatively with climate 
change.
    Our Response: We agree that threat factors must be considered 
cumulatively to determine if factors considered together may be a 
threat to the species. In the case of the wolverine DPS, in the 
proposed rule we concluded that trapping and the effects of small 
population size were threats to this growing population only 
cumulatively when considered with the projected effects of climate 
change on wolverine habitat. However, as described in this document, 
upon further consideration of the best available information, we have 
re-evaluated our determination on the effects of climate change on 
wolverine population persistence in light of new information presented 
below under Factor A. We now conclude that there is not sufficient 
information on the response of the wolverine DPS to the projected 
changes in climate and resulting impacts to habitat, and we do not find 
the effects of climate change to likely pose a risk of extinction to 
the DPS at this time. We find that absent a threat resulting from 
climate change, no other stressor rises to the level of a likely risk 
of extinction to the DPS, either individually or cumulatively, that 
results in the wolverine DPS meeting the definition of an endangered or 
threatened species under the Act.
    (61) Comment: One commenter said that wolverine attraction to road 
kill is a risk that should be considered.
    Our Response: Wolverines have been killed by automobiles on 
highways. It is uncertain whether road kill may have been a factor in 
some of these mortalities. We have no evidence that highway mortality 
is significant to the wolverine population or whether or not attraction 
to road kill is a significant contributor to mortality events. This 
hypothesis remains speculative until additional scientific evidence is 
obtained.
    (62) Comment: One commenter opined that heavy recreational use does 
not occur in the central Idaho area where the recreation study 
(Heinemeyer et al. 2012) is occurring.
    Our Response: The term ``heavy'' when used to describe recreational 
use is a subjective term. We consider some of the recreational use in 
the study area in central Idaho to be locally heavy. The scientists 
conducting the study consider the range of recreational use in central 
Idaho to be sufficient to detect effects on wolverines from recreation, 
if any.
    (63) Comment: Many commenters took issue with our conclusions 
regarding winter recreation. Some thought that winter recreation is a 
threat. Others thought that the recreation study in Idaho could be 
interpreted to mean that there are significant effects to wolverines. 
Still others thought that the Service should only rely on peer-reviewed 
literature when assessing the effects of recreation on the DPS of 
wolverines.
    Our Response: The best available information does not indicate that 
wolverines are significantly affected by winter recreation. 
Furthermore, the

[[Page 47532]]

question in the listing process is not whether there is any effect, but 
whether that effect rises to such a level of a threat to the DPS such 
that the DPS meets the definition of endangered or threatened now or in 
the foreseeable future. We find no evidence that winter recreation 
occurs on such a scale and has effects that cause the DPS to meet the 
definition of a threatened or endangered species. We continue to 
conclude that winter recreation, though it likely affects wolverines to 
some extent, is not a threat to the DPS.
    (64) Comment: Several commenters suggested that changes in 
technology make access to wolverine habitat easier for snowmobilers. 
Others pointed out that Inman et al. (2013) says snowmobile use may 
affect wolverines.
    Our Response: We agree that changes in technology increase access 
to wolverine habitat by snowmobilers and that winter recreation may 
affect wolverines. Significant effects to wolverines from winter 
recreation remain to be demonstrated scientifically. We do not agree 
that the available scientific information supports the conclusion that 
winter recreation is a threat to the DPS, for reasons discussed below 
under Factor A.
    (65) Comment: One commenter wondered if there is there any 
information on wolf predation on wolverines and whether it might be 
significant to the listing decision.
    Our Response: Wolves have been known to kill wolverines on 
occasion, but we are unaware of any information suggesting that wolf 
predation is a significant source of mortality for the DPS.
    (66) Comment: Several commenters thought that immigration from 
Canada would bolster genetic diversity of wolverines in the DPS given 
that wolverines recolonized the DPS from Canada.
    Our Response: It is possible that future immigration from Canada 
will provide for an increase in the genetic diversity of wolverines in 
the contiguous United States; however, data presented in Schwartz et 
al. (2009) suggest that wolverines are not presently moving between 
populations in the DPS and Canada with enough frequency to overcome the 
effects of genetic drift.
    (67) Comment: Several commenters and States thought that wolverines 
may be able to adapt to earlier snowmelt by denning earlier.
    Our Response: It is possible that wolverines may be more adaptable 
than the currently available scientific information would suggest. 
Earlier denning has not been reported for wolverines.
    (68) Comment: The listing proposal fails to conduct an independent 
assessment of each of the four possible listing options: species, DPS, 
significant portion of range of the species, and significant portion of 
range of the DPS.
    Our Response: In writing the proposed listing rule, we considered 
all of the possible listing options, including significant portion of 
the range (please refer to Significant Portion of the Range analysis, 
below).
    (69) Comment: Several commenters suggested that small effective 
population size for wolverines in the northern Rocky Mountains is a 
significant threat regardless of climate change.
    Our Response: In a static population, small effective population 
size may be a conservation concern because it can lead to loss of 
genetic diversity. In the case of the wolverine DPS, we expect that 
continued population growth is likely to ameliorate the effects of 
small effective population size by increasing the wolverine population 
and providing for better connectivity between subpopulations. 
Therefore, small effective population size is not a threat, but rather 
a risk factor that may resolve itself as population growth continues.
    (70) Comment: Several States commented that there is no provision 
in the Act to list a DPS of a subspecies; therefore the DPS is invalid.
    Our Response: We continue to support recognition of the wolverine 
DPS. The Act provides for recognition of DPSs for vertebrate species. 
The word ``species'' in that context refers to species or subspecies. 
Furthermore, our 1996 Policy Regarding the Recognition of Distinct 
Vertebrate Population Segments Under the Endangered Species Act states: 
``The Services maintain that the authority to address DPS's extends to 
species in which subspecies are recognized, since anything included in 
the taxon of lower rank is also included in the higher ranking taxon'' 
(61 FR 4722, p. 4724; February 7, 1996). Therefore, it is appropriate 
to recognize the wolverine DPS as a listable entity.

Summary of Factors Affecting the Species

    Section 4 of the Act (16 U.S.C. 1533), and its implementing 
regulations at 50 CFR part 424, set forth the procedures for adding 
species to the Federal Lists of Endangered and Threatened Wildlife and 
Plants. Under section 4(a)(1) of the Act, we may list a species based 
on (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. Listing actions may be warranted based on any of 
the above threat factors, singly or in combination. Each of these 
factors is discussed below.

Factor A. The Present or Threatened Destruction, Modification, or 
Curtailment of Its Habitat or Range

    Under Factor A, we will discuss a variety of impacts to wolverine 
habitat including: (1) Effects of climate change, (2) human use and 
disturbance, (3) dispersed recreational activities, (4) infrastructure 
development, (5) transportation corridors, and (6) land management. 
Many of these impact categories overlap or act in concert with each 
other to affect wolverine habitat. Climate change effects are discussed 
under Factor A because although increased temperatures due to climate 
change may affect wolverines directly by creating physiological stress, 
the primary potential impact of climate change on wolverines is thought 
to be through changes to the availability and distribution of wolverine 
habitat.
Reduction in Habitat Due to Climate Change
    Our analyses under the Act include consideration of the likely 
effects of ongoing and projected changes in climate. The terms 
``climate'' and ``climate change'' are defined by the Intergovernmental 
Panel on Climate Change (IPCC). ``Climate'' refers to the mean and 
variability of different types of weather conditions over time, with 30 
years being a typical period for such measurements, although shorter or 
longer periods also may be used (IPCC 2013, p. 1450). The term 
``climate change'' thus refers to a change in the mean or variability 
of one or more measures of climate (e.g., temperature or precipitation) 
that persists for an extended period, typically decades or longer, 
whether the change is due to natural variability, human activity, or 
both (IPCC 2013, p. 1450). Various types of changes in climate can have 
direct or indirect effects on species. These effects may be positive, 
neutral, or negative and they may change over time, depending on the 
species and other relevant considerations, such as the effects of 
interactions of climate with other variables (e.g., habitat 
fragmentation) (IPCC 2007, pp. 8-14, 18-19).
    We recognize that there are scientific uncertainties on many 
aspects of

[[Page 47533]]

climate change, including the role of natural variability in climate. 
In our listing proposal (78 FR 7874-7877), we relied both on synthesis 
documents (e.g., IPCC 2007; Karl et al. 2009) that present the 
consensus view of a very large number of experts on climate change from 
around the world, and on analyses that relate the effects of climate 
change directly to wolverines (Brock and Inman 2007, pers. comm.; 
Gonzalez et al. 2008, entire; Brodie and Post 2009, entire; Peacock 
2011, entire; McKelvey et al. 2011, entire; Johnston et al. 2012, 
entire). We argued that due to lack of downscaling (Peacock 2011), 
failure to consider both temperature and precipitation (Brock and Inman 
2007, pers. comm.; Gonzalez et al. 2008), limited analysis area 
(Johnson et al. 2012), and inappropriate inferences from harvest data 
(Brodie and Post 2010), many analyses do not represent the best 
available science. In our proposed listing rule, we identified McKelvey 
et al. (2011) as the best scientific information available regarding 
impacts of climate change to wolverine habitat because the authors 
incorporated both temperature and precipitation, and downscaled 
analyses to reflect the regional climate patterns and topography found 
within the range of wolverines in the contiguous United States.
    While we still agree that McKelvey et al. (2011) is the most 
sophisticated analysis of impacts of climate change at a scale specific 
to the range of the wolverine, science panel members (Service 2014, p. 
29), public comments, and recent scientific information (Potter et al. 
2013, entire; Franklin et al. 2012, entire) emphasize limitations 
inherent in downscaled climate models and the importance of 
understanding the effect of climate-data spatial resolution on 
wolverine viability in complex terrain. Downscaling techniques improve 
understanding of climate at smaller, regional scales compared to Global 
Climate Models, but their spatial resolution may still be inadequate to 
describe the variability of microclimates in which organisms live 
(Potter et al. 2013, p. 2935). Franklin et al. (2012, pp. 478-482) show 
that there can be large differences between suitable habitats predicted 
from coarse versus fine-scale climate models, and concluded that, on 
average, a scale approximately twice as fine as that used in McKelvey 
et al. (2011, entire) (280 m vs. 500 m) is adequate, and that in rugged 
terrain even finer models (e.g., 10-30 m) may be needed to represent 
significant microclimates. Potter et al. (2014, p. 2934) propose that 
the ideal spatial resolution is related to organismal body size and 
lies between 1 and 10 times the length or height of the organism. 
McKelvey et al. (2011, p. 2895) reached similar conclusions about their 
own modeling efforts: ``although wolverine distribution is closely tied 
to persistent spring snow cover (Copeland et al. 2010), we do not know 
how fine scale changes in snow patterns within wolverine home range may 
affect population persistence.'' We concur; an improved understanding 
of how microclimatic variation alters the habitat associations of 
wolverines at fine spatial scales will be useful in understanding 
climate impacts on wolverine habitat.
    Additionally, great difficulty still exists in predicting changes 
in precipitation with climate models, especially compared to the more 
confident predictions for temperature (Torbit 2014, pers. comm.). Newer 
modeling techniques suggest that higher elevations could maintain more 
snow than previously thought and possibly even receive more snow than 
historical records show due to climate change (Torbit 2014, pers. 
comm.; Ray et al. 2008). While these contemporary techniques have not 
been applied to the northern portions of the proposed wolverine DPS (78 
FR 7873), and much of the high elevation wolverine range is currently 
unoccupied, they demonstrate that the science associated with climate 
models is continuing to change, highlighting the uncertainty of our 
conclusions in the proposed rule (78 FR 7877). This new information 
highlighting the importance of scale and use of modern, quantitative 
techniques to evaluate uncertainty in climate assessments have prompted 
us to re-evaluate our original conclusions in the proposed rule (78 FR 
7874-7876) that wolverine habitat will decline at the predicted rates 
suggested in McKelvey et al. (2011). Modern assessment techniques that 
include slope, aspect, and other topographic information are now 
available and can be used to predict precipitation, including snowfall 
at finer scales that could be more aligned with existing or potential 
wolverine habitat (Torbit 2014, pers. comm.; Ray et al. 2008, pp. 17-
23; Torbit 2014, pers comm). Based upon our re-evaluaton of the best 
scientific data available, we no longer find that the existing 
scientific information supports our conclusions in the proposed rule 
(78 FR 7874-7876) that climate change will result in a 31 percent (mid-
century) to 63 percent (end of century) reduction in wolverine habitat 
in the foreseeable future.
Climate Effects to Wolverines
    We based our proposal (78 FR 7874-7877) on the best available data 
at the time, which we intitially interpreted as demonstrating that 
wolverines require deep snow persisting through the denning period to 
successfully live and reproduce, and that reduction of this habitat 
feature would proportionally reduce wolverine habitat, or to an even 
greater extent if habitat reduction involved increasing fragmentation. 
We analyzed the effects of climate change on wolverines through three 
primary mechanisms: (1) Reduced snowpack and earlier spring runoff, 
which we argued would reduce suitable habitat for wolverine denning; 
(2) increase in summer temperatures beyond the physiological tolerance 
of wolverines; and (3) ecosystem changes due to increased temperatures, 
which we reasoned would move lower elevation ecosystems to higher 
elevations, thereby eliminating high-elevation ecosystems on which 
wolverines depend and increasing competitive interactions with species 
that currently inhabit lower elevations. These mechanisms would tend to 
push the narrow elevational band that wolverines use into higher 
elevation, and due to the conical structure of mountains, this upward 
shift would result in reduced overall suitable habitat for wolverines.
Deep Snow and Denning
    The literature generally does not reflect any studies that tested 
whether wolverines have an obligate relationship with deep and/or 
contiguous snow cover; therefore, we convened an expert science panel 
to provide further guidance specifically on this issue (Service 2014, 
entire). Expertise included climatologists and remote sensing experts, 
biologists, and ecologists. Panelists strongly supported an obligate 
relationship between wolverines and deep snow at the scale of the den 
site, expressed uncertainty in the relationship between wolverines and 
deep snow at the scale of the home range and DPS' range, and also 
expressed uncertainty in the relationship between wolverines and 
contiguous snow at the home range and DPS range scales (Service 2014, 
pp. 8-13). Therefore, based on the literature (Pulliainen 1968; 
Copeland 1996; Magoun and Copeland 1996; Magoun and Copeland 1998; 
Banci 1994; Inman et al. 2007; Copeland et al. 2010), the opinion of 
expert panelists, and the peer reviews, it is reasonable to believe 
that wolverines select for den sites likely to have deep snow that will 
persist until some point into the spring.

[[Page 47534]]

    The primary hypothesis put forward in the proposed listing rule (78 
FR 7875) is that a loss of areas with persistent spring snow cover will 
result in a loss of potential wolverine den sites, or failure of den 
sites, negatively impacting future abundance and trend. Den sites are 
correlated with snow (Copeland et al. 2010, entire), and experts in the 
science panel expressed an opinion that wolverines require deep snow 
for den sites. However, the predictions from McKelvey et al. (2011) 
about future habitat loss rely on the Copeland model (Copeland et al. 
2010, entire) to describe what habitat is and then to predict how much 
of it will be lost. The habitat described in the Copeland model 
includes areas that retained snow until May 15, in as few as 1 of 7 
years. In other words, if an area retained snow in only 1 of 7 years, 
it was still included in the model describing habitat, and 97.9 percent 
of the sample of den sites fell within this area. That means that some 
proportion of those den sites fell within an area that did not retain 
snow each year. This brings into question the reliability of the 
conclusion that snow persisting until May 15 is a necessary condition 
for wolverine reproduction.
    We are aware of no evidence that den sites are currently scarce or 
lacking, or that they currently limit wolverine reproduction. In other 
words, even if some den sites were to be lost as a result of climate 
change, due to the expansive size of female wolverine home ranges, it 
is likely that many potential additional den sites would remain 
available. Further, we have no information that we could use to predict 
at what level of reduced spring snow coverage den sites would become 
limiting. Inman et al. (2013) estimated available habitat capacity in 
the U.S. to be approximately 644 wolverines (95 percent CI = 506-1881), 
and that current population size is currently approximately half of 
capacity. This estimated current abundance level (322) is similar to 
our rough estimate of population abundance of 250-300 wolverines in our 
proposed listing rule. The current estimated abundance level, 
significantly below estimated carrying capacity for a population that 
is still increasing, suggests that den sites are likely not currently 
limiting wolverine reproduction and population abundance.
    We do not appear to know at this point with any reliability what 
the causal relationship is between the feature of deep persistent 
spring snow and wolverine dens (Service 2014, pp. 10, 28-29); that is, 
we do not understand why wolverines appear to require deep persistent 
spring snow for denning. Several hypotheses exist to explain the 
correlation between den sites and snow, such as den structure, food 
refrigeration, security from predators, or a thermal buffer for kits in 
the den, but these hypotheses have not been tested. All of these 
hypotheses seem possible and worth testing, but without such biological 
information demonstrating the causal mechanism, it is difficult to 
determine beyond speculation if, and how soon, the effects of climate 
change (e.g., earlier snowmelt) may influence or limit availability of 
den sites, habitat, and ultimately wolverine abundance, trend, and 
viability into the future.
    Only two studies have investigated hypotheses regarding potential 
limiting factors for wolverines. Persson (2005) tested the hypothesis 
that wolverine reproduction was affected by winter food availability. 
He found that provision of additional food resources to wolverines, 
when compared to a control group not receiving supplemental food, 
resulted in higher reproduction. He suggests that female wolverine 
reproduction is determined by their condition in winter, which is 
determined by past year's reproductive costs and food availability. In 
his comments on the proposed listing rule, Copeland (November 26, 2013, 
p. 2) also touched on food availability as the limiting factor as he 
stated his belief that wolverine densities are highly variable and tied 
to food availability. He points to current differences in population 
densities between Glacier National Park and central Idaho that he 
believes are most likely related to food availability. He hypothesized 
that Glacier Park provides a year-round higher availability of carrion 
and therefore higher densities of wolverines.
    In summary, the pertinent question that remains is if and when a 
decrease in deep, persistent spring snow will limit the availability of 
den sites, therefore causing a population decline in the future. 
Available information does not yet allow us to predict if and when that 
may occur.
Year-Round Relationship Between Wolverine Habitat and Persistent Snow 
Cover
    Copeland et al. (2010) estimated persistent spring snow cover 
(April 24 to May 15 in at least 1 of 7 years during the period from 
2000 to 2006, Copeland et al. (2010, p. 235)) using MODIS satellite 
data, and the resulting mapped area represents their bioclimatic model 
describing wolverine habitat (Copeland et al. 2010, Figure 1). They 
indicated that of the total 562 dens from North America, Finland, 
Norway, and Sweden, 97.9 percent of den sites occurred in pixels that 
were snow covered through May 15 in at least 1 of the 7 years (that is, 
they were within the modeled habitat). Their results indicated that not 
all, but 95 percent of summer and 86 percent of winter telemetry 
locations of wolverine, were within the modeled habitat area they 
described as having persistent deep snow cover.
    However, the location dataset relies heavily on data collected in 
Scandinavia and does not consider several available datasets, such as 
trapping locations, location records from States and provinces, and 
telemetry data from the eastern Canadian provinces. In their comments, 
the State of Idaho indicated that only 68.6 percent of Idaho's verified 
wolverine observations (312 of 415) were within Copeland et al.'s 
(2010) habitat model (Idaho Fish and Game Comments, November 25, 2013, 
p. 2). Recent publications have suggested that factors beyond those 
included by Copeland et al. (2010) such as land cover (e.g., vegetative 
type), topography, human footprint, and snow depth should be 
incorporated into predictive models to accurately describe wolverine 
habitat because these factors appear to also influence primary 
wolverine habitat use (Inman et al. 2013, p. 278; Fisher et al. 2013, 
p. 712). These publications appear to support the idea that wolverines 
generally use areas of higher elevation; steeper terrain; more snow; 
fewer roads; less human activity; and, generally, snow cover persisting 
into the spring. Note, however, that Inman et al. (2013, p. 278) used 
snow cover on April 1, not snow cover until May 15, as a variable in 
their best-fitting model. Lastly, Copeland himself (November 26, 2013, 
p. 2) stated his belief that there are other factors beyond snow that 
influence wolverine distribution. Taken together, the available body of 
literature, our peer review, the science panel (Service 2014, entire), 
and public comment appear to indicate that: (1) Wolverines use areas 
with deep snow; (2) wolverines are occasionally observed outside of the 
area that has snow until May 15; (3) areas were included in the 
Copeland et al. (2010) predictive habitat model that may have had May 
15 snow in as little as 1 of 7 years studied; and (4) factors other 
than snow cover on May 15 may also influence wolverine habitat use.
    McKelvey et al. (2011, Figure 4) suggested that wolverine habitat 
in the contiguous United States, which currently supports approximately 
250 to 300 wolverines, is shrinking and will likely continue to shrink 
and become increasingly fragmented with increased

[[Page 47535]]

climate warming. They projected a 31 percent in habitat loss throughout 
the range of the DPS by the time interval centered on 2045 (2030-2059). 
That loss expands to 63 percent of wolverine habitat by the time 
interval centered on 2085 (2070 to 2099). In our proposed listing rule, 
we reasoned that due to the spatial needs of wolverines and the limited 
availability of suitable wolverine habitat in the contiguous United 
States, this projected habitat loss would be likely to result in a loss 
of wolverine numbers that is greater than the overall loss of habitat 
area. However, upon reconsideration of the best available information, 
given our uncertainty in the relationship between wolverines and snow, 
we conclude it is not clear that these predictions of snow loss 
represent an equivalent loss of habitat. That is, while it may be 
likely that habitat will decrease over time due to earlier snow melt, 
if wolverines also use areas outside of the area covered with snow 
until May 15, this reduction in snow cover may not equate linearly to 
an equivalent loss of wolverine habitat; thus, McKelvey et al. (2011) 
may overestimate the loss of wolverine habitat (Franklin et al. 2013, 
p. 481).
    Furthermore, based on our own calculations, given average home 
range sizes of male and female wolverines, the predicted habitat 
remaining after 2085 (McKelvey et al. 2010) could support 344 (95 
percent CI: 250-421) wolverines (versus the current estimate of 250-
300) in the contiguous United States, with the bulk (283; 95 percent 
CI: 110-347) of individuals estimated in the Northern Rocky Mountains 
in 2070-2099. These estimates do not include possible additional 
occupancy of potentially important wolverine habitat in the Sierra 
Nevada Mountains and portions of Oregon, which were beyond the 
geographic scope of the McKelvey et al.'s (2011) analysis. In other 
words, even under future conditions of projected habitat loss, we 
estimate there would be sufficient habitat available in the United 
States to potentially continue supporting wolverine populations at 
roughly the same level of abundance as at present. Thus, even if future 
populations were potentially limited by available habitat for future 
growth, the data do not suggest that the population of wolverines in 
the contiguous United States would necessarily be forced into decline 
by loss of habitat. In addition, as discussed above, if the obligate 
relationship with deep snow is only at the den site and not across the 
overall range of a wolverine and the DPS in general, specific snow 
variation due to elevation and topography also calls into question the 
conclusion that overall snow loss across the range of the DPS will 
equate to a specific loss of wolverine habitat.
    Our proposed listing rule also discussed the consequences of 
habitat patches becoming progressively isolated from each other due to 
climate change (78 FR 7876). We concluded that reduced connectivity to 
other subpopulations could increase the likelihood of subpopulations 
lost due to demographic stochasticity, impairing the functionality of 
the wolverine metapopulation in the contiguous United States. McKelvey 
et al. (2011) concluded that continued warming trends may create small 
and isolated populations, among which the energetic costs of traveling 
will be high. However, they also stated that while contiguous areas of 
spring snow cover are predicted to become smaller and more isolated 
over time, large (>2000 km\2\) contiguous areas of wolverine habitat 
are predicted to persist within the study area throughout the 21st 
century for all model projections (McKelvey et al. 2011, pp. 2992, 
2994). By the late 21st century, their dispersal modeling predicts that 
habitat isolation at levels associated with genetic isolation of 
populations becomes widespread.
    Currently available information indicates that wolverines are known 
to travel long distances through anthropogenically altered terrain, and 
habitats that are otherwise unsuitable for long-term survival (Moriarty 
et al., entire; Inman et al. 2009, pp. 22-28); in fact, this propensity 
was cited as complicating our analysis of present and past range (78 FR 
7869). Wolverines are able to successfully disperse between habitats, 
despite the level of development that is currently taking place in the 
current range of the DPS (Copeland 1996, p. 80; Copeland and Yates 
2006, pp. 17-36; Inman et al. 2007a, pp. 9-10; Pakila et al. 2007, pp. 
105-109; Schwartz et al. 2009, Figures 4, 5). In recent years, 
individual wolverines have been documented in Colorado (2010), the 
Sierra Nevada range in California (2008), and the Uinta Range of Utah 
and Wyoming (2014), indicating some dispersal to known unoccupied range 
is occurring, and quite likely necessitated travel through lower 
elevation areas that do not retain deep snow. Although most studies 
document greater dispersal distances for males than females (Hornocker 
and Hash 1981, p. 1298; Banci 1994, pp. 117-118; Moriarty et al. 2009, 
entire; Inman et al. 2009, pp. 22-28; Brian 2010, p. 3; Copeland and 
Yates 2006, Figure 9), Vangen et al. (2001, p. 1644) found that both 
males and females are capable of long-distance dispersal. One hundred 
percent of males and 69 percent of females dispersed, with average 
dispersal distances for males of 51  30km (range = 11-101 
km) and 60  48 km (range = 15-178 km) for females, although 
differences between males and females were not significant. Vangen et 
al. (2001, p. 1647) reflect on other dispersal distances reported in 
the literature from Idaho (two males dispersed 16 and 199 km; Copeland 
1996) and Alaska (one male dispersed 378 km; Gardner 1985) and 
concluded that both sexes have the capacity to establish themselves far 
away from their natal areas, thereby ensuring recolonization and gene 
flow between subpopulations. Inman et al. (2013, p. 284), however, 
suggest that female long-distance dispersal is likely to be very 
infrequent.
    Given the available body of literature, the proposed listing rule 
(78 FR 7864; February 4, 2013), science panel (Service 2014, entire), 
and peer review, it is reasonable to predict that if observed warming 
trends (Hamlet and Lettenmaier 1999, p. 1609; Brown 2000, p. 2347; Mote 
2003, p. 3-1; Christensen et al. 2004, p. 347; Knowles et al. 2006, pp. 
4548-4549) continue within the larger range of wolverine, and areas 
with deep snow become smaller and more isolated, connectivity and 
genetic exchange among wolverine populations will decrease over time. 
At the same time, however, as discussed above, relatively large areas 
of wolverine habitat are predicted to persist throughout the 21st 
century for all model projections, and wolverines are capable of 
traversing great lengths, thus ameliorating the potential negative 
consequences of increasing distances between areas of suitable habitat. 
Therefore, as discussed above, with such uncertainty in wolverine 
response to changes predicted association with climate modeling, we do 
not know if and to what extent genetic exchange will be limited and in 
what timeframe. Furthermore, the best available information does not 
indicate that climate change effects have hindered population growth 
and expansion, or caused any contraction of habitat at this time (Inman 
et al. 2013, p. 277).
    We acknowledged in our proposed listing rule (78 FR 7868; February 
4, 2013), that with no systematic census across the range of the DPS in 
the United States, the current population level of wolverines is not 
known with certainty. As we stated in the proposal, our best estimate 
of current population abundance was based on knowledge of occupied 
habitat and average densities: approximately 250 to 300 wolverines in

[[Page 47536]]

the lower 48 States. Since the proposed listing rule was published, 
Inman et al. (2013) published an estimated available habitat capacity 
to be approximately 644 wolverines (95 percent CI = 506-1881), and 
estimated that the current population size in the contiguous United 
States is currently approximately half of capacity (in other words, 
roughly 322 individuals), and these are believed to be expanding in 
number and range (Aubry et al. 2007, p. 2151). Population growth and 
expansion has been documented in the North Cascades and Northern Rocky 
Mountains (78 FR 7881-7872), and as has been noted above, individuals 
have successfully dispersed to Colorado, California and Utah. This 
estimated current abundance level (322) is similar to our rough 
estimate of population abundance of 250-300 wolverines in our proposed 
listing rule. Accordingly, our conclusion in the proposed rule (78 FR 
78049) that climate change has likely already reduced the overall areal 
extent and distribution of wolverine habitat seems largely speculative. 
While one could conjecture that dispersers to the southern portion of 
the DPS are occurring due to habitat loss in the northern part of the 
DPS, one could just as easily conclude that these dispersers are the 
result of an increasing population with dispersers looking to colonize 
largely unoccupied habitat. This consideration, coupled with the 
results of the Inman et al. (2013) publication indicating that 
available habitat could support a population in the United States twice 
as large as that at present, suggests that there is no evidence of 
habitat contraction at this time due to climate change.
    Finally, our proposal suggested that the projected increase in 
summer temperatures and elimination of high-elevation ecosystems on 
which wolverines depend may negatively impact wolverines. We reiterate 
our earlier discussion of the limitations and uncertainty inherent in 
downscaled climate models. Available information suggests that climate 
changes may indeed affect wolverine habitat; however, the specific 
response or sensitivity of the wolverines to these current and 
forecasted changes is sufficiently uncertain at this time, such that we 
cannot reasonably project the future conservation status of the DPS 
based on any such changes that may occur.

Summary of Impacts of Climate Changes

    There is significant evidence that the climate within the larger 
range of the wolverine is warming, affecting snow patterns and 
associated wolverine habitat. The biological response of wolverine 
populations to such changes, however, cannot reasonably be deduced with 
an acceptable degree of certainty. At this time, we do not know how the 
effects of climate change will impact wolverine populations for the 
following reasons:
    (1) Wolverines are believed to be expanding both within the area 
currently inhabited by wolverines as well as into suitable habitat not 
currently occupied and/or occupied with a few individuals. Recent 
evidence suggests that there is suitable habitat available within the 
contiguous United States to support a wolverine population twice as 
large as that at present. Even under conditions of future reduced 
snowpack as a consequence of climate change, sufficient habitat will 
likely remain to maintain the wolverine population at the current level 
of abundance.
    (2) There is strong support for the existence of an obligate 
relationship between wolverines and deep spring snow at the den site; 
however, available information suggests that den sites are not 
currently limiting wolverines, and we do not have sufficient 
information to predict if and when any limitation will occur in the 
future. Additionally, support for the obligate relationship between 
wolverine and deep snow at an individual wolverine's home range or the 
DPS' range in general is lacking. That is, we do not have sufficient 
information to suggest that deep snow is required by wolverines 
throughout their home ranges, beyond the level of the individual den 
site.
    (3) We do not have sufficient information to understand the 
specific response of wolverines to future effects of changes in 
climate. Although we do not question that climate change is likely to 
alter the habitats utilized by wolverines to some degree, we have no 
data to inform us as to the likely biological response of wolverine 
populations to those habitat changes, and, most germane for the 
purposes of the Act, no data to reliably suggest that the anticipated 
changes are such that the viability of wolverine populations in the 
contiguous United States will be at risk.
    Therefore, based on our analysis of the best available scientific 
information, we do not find the effects of climate change to likely 
place the wolverine DPS in danger of extinction in the foreseeable 
future and therefore meeting the definition of a threatened species 
under the Act.
Habitat Impacts Due to Human Use and Disturbance
    Because wolverine habitat is generally inhospitable to human use 
and occupation and most wolverine habitat is also federally managed in 
ways that must consider environmental impacts, wolverines are somewhat 
insulated from impacts of human disturbances from industry, 
agriculture, infrastructure development, or recreation. Human 
disturbance in wolverine habitat in the contiguous United States has 
likely resulted in the loss of some minor amount of wolverine habitat, 
although this loss has not yet been quantified. Sources of human 
disturbance to wolverines has been speculated to include winter and 
summer recreation, housing and industrial development, road corridors, 
and extractive industry (such as logging or mining). In the contiguous 
United States, these human activities and developments sometimes occur 
within or immediately adjacent to wolverine home ranges, such as in 
alpine or boreal forest environments at high elevations on mountain 
slopes. They can also occur in a broader range of habitats that are 
occasionally used by wolverines during dispersal or exploratory 
movements--habitats that are not suitable for the establishment of home 
ranges and reproduction.
    Little is known about the behavioral responses of individual 
wolverines to human presence, or about the DPS' ability to tolerate and 
adapt to repeated human disturbance. Some hypothesize that disturbance 
may reduce the wolverine's ability to complete essential life-history 
activities, such as foraging, breeding, maternal care, routine travel, 
and dispersal (Packila et al. 2007, pp. 105-110). However, wolverines 
have been documented to persist and reproduce in areas with high levels 
of human use and disturbance including developed alpine ski areas and 
areas with motorized use of snowmobiles (Heinenmeyer 2012, entire). 
This suggests that wolverines can survive and reproduce in areas that 
experience human use and disturbance. How or whether effects of 
disturbance extend from individuals to characteristics of 
subpopulations and populations, such as vital rates (e.g., 
reproduction, survival, emigration, and immigration) and gene flow, and 
ultimately to wolverine population or metapopulation persistence, 
remains unknown at this time.
    Wolverine habitat is characterized primarily by spring snowpack, 
but also by the absence of human presence and development (Hornocker 
and Hash 1981, p. 1299; Banci 1994, p. 114; Landa

[[Page 47537]]

et al. 1998, p. 448; Rowland et al. 2003 p. 101; Copeland 1996, pp. 
124-127; Krebs et al. 2007, pp. 2187-2190). This negative association 
with human presence is sometimes interpreted as active avoidance of 
human disturbance, but it may simply reflect the wolverine's preference 
for cold, snowy, and high-elevation habitat that humans avoid. In the 
contiguous United States, wolverine habitat is typically associated 
with high-elevation (e.g., 2,100 m to 2,600 m (6,888 ft to 8,528 ft)) 
subalpine forests that comprise the Hudsonian Life Zone (weather 
similar to that found in northern Canada), environments not typically 
used by people for housing, industry, agriculture, or transportation. 
However, a variety of activities associated with extractive industry, 
such as logging and mining, as well as recreational activities in both 
summer and winter are located in a small amount of occupied wolverine 
habitat.
    For the purposes of this determination, we analyze human 
disturbance in four categories: (1) Dispersed recreational activities 
with primary impacts to wolverines through direct disturbance (e.g., 
snowmobiling and heli-skiing); (2) disturbance associated with 
permanent infrastructure, such as residential and commercial 
developments, mines, and campgrounds; (3) disturbance and mortality 
associated with transportation corridors; and (4) disturbance 
associated with land management activities, such as forestry or fire/
fuels reduction activities. Overlap between these categories is 
extensive, and it is often difficult to distinguish effects of 
infrastructure from the dispersed activities associated with that 
infrastructure. However, we conclude that these categories account for 
most of the human activities that occur in occupied wolverine habitat.
Dispersed Recreational Activities
    Dispersed recreational activities occurring in wolverine habitat 
include snowmobiling, heli-skiing, hiking, biking, off- and on-road 
motorized use, hunting, fishing, and other uses.
    One study documented (in two reports) the extent that winter 
recreational activity spatially and temporally overlapped modeled 
wolverine denning habitat in the contiguous United States (Heinemeyer 
and Copeland 1999, pp. 1-17; Heinemeyer et al. 2001, pp. 1-35). This 
study took place in the Greater Yellowstone Area (GYA) in an area of 
high dispersed recreational use. The overlap of modeled wolverine 
denning habitat and dispersed recreational activities was extensive. 
Strong temporal overlap existed between snowmobile activity (February-
April) and the wolverine denning period (February-May). During 2000, 
six of nine survey units, ranging from 3,500 to 13,600 (ha) (8,645 to 
33,592 (ac)) in size, showed evidence of recent snowmobile use. Among 
the six survey units with snowmobile activity, the highest use covered 
20 percent of the modeled denning habitat, and use ranged from 3 to 7 
percent over the other survey units. Snowmobile activity was typically 
intensive where detected.
    Three of nine survey units in this study showed evidence of skier 
activity (Heinemeyer and Copeland 1999, p. 10; Heinemeyer et al. 2001, 
p. 16). Among the three units with activity, skier use covered 3 to 19 
percent of the survey unit. Skiers also intensively used the sites they 
visited. Combined skier and snowmobile use covered as much as 27 
percent of potential denning habitat in one unit where no evidence of 
wolverine presence was detected. We conclude from this study that in 
some areas, high recreational use may coincide substantially with 
occupied wolverine habitat. The authors of the study cited above chose 
the study area based on its unusually high level of motorized 
recreational use. Although we do not have information on the overlap of 
wolverine and winter recreation in the remaining part of the contiguous 
U.S. range, it is unlikely that any of the large areas of wolverine 
habitat such as the southern Rocky Mountains, Northern Rocky Mountains, 
GYA, or North Cascades get the high levels of recreational use seen in 
the portion of the GYA examined in this study across the entire 
landscape. Rather, each of these areas has small (relative to wolverine 
home range size) areas of intensive recreational use (ski resorts, 
motorized play areas) surrounded by a landscape that is used for more 
dispersed recreation such as backcountry skiing or snowmobile trail 
use.
    Although we can demonstrate that recreational use of wolverine 
habitat is heavy in some areas, we do not have any information to 
suggest that these activities have negative effects on wolverines. No 
assessments of anthropogenic disturbance on wolverine den fidelity, 
food provisioning, or offspring survival have been conducted. 
Disturbance from foot and snowmobile traffic associated with historical 
wolverine control activities (Pulliainen 1968, p. 343), and field 
research activities, have been purported to cause maternal females to 
abandon natal dens and relocate kits to maternal dens (Myrberget 1968, 
p. 115; Magoun and Copeland 1998, p. 1316; Inman et al. 2007c, p. 71). 
However, this behavior appears to be rare, even under intense 
disturbance associated with capture of family groups at the den site 
(Persson et al. 2006, p. 76), and other causes of den abandonment may 
have acted in these cases. Preliminary results from an ongoing study on 
the potential impacts of winter recreation on wolverines in central 
Idaho indicate that wolverines are present and reproducing in this area 
in spite of heavy recreational use, including a developed ski area; 
dispersed winter and summer recreation; and dispersed snowmobile use 
(Heinemeyer et al. 2012, entire). The security of the den and the 
surrounding foraging areas (i.e., protection from predation by 
carnivores) is an important aspect of den site selection. Abandonment 
of natal and maternal dens may be a preemptive strategy that females 
use in the absence of predators (i.e., females may abandon dens without 
external stimuli), as this may confer an advantage to females if 
prolonged use of the same den makes that den more evident to predators. 
Evidence for effects to wolverines from den abandonment due to human 
disturbance is lacking. The best scientific information available does 
not substantiate dispersed recreational activities as a threat to 
wolverine.
    Most roads in wolverine habitat are low-traffic volume dirt or 
gravel roads used for local access. Larger, high-volume roads are dealt 
with below in the section ``Transportation Corridors.'' At both a site-
specific and landscape scale, wolverine natal dens were located 
particularly distant from public (greater than 7.5 km (4.6 mi)) and 
private (greater than 3 km (1.9 mi)) roads (May 2007, pp. 14-31). 
Placement of dens away from public roads (and away from associated 
human-caused mortality) was also a positive influence on successful 
reproduction. It is not known if the detected correlation is due to the 
influence of the roads, but we find it unlikely that wolverines avoid 
the type of low-use forest roads that generally occur in wolverine 
habitat. Other types of high-use roads are rare in wolverine habitat 
and are not likely to affect a significant amount of wolverine habitat 
(see ``Transportation Corridors'' section, below).
Infrastructure Development
    Infrastructure includes all residential, industrial, and 
governmental developments, such as buildings, houses, oil and gas 
wells, and ski areas. Infrastructure development on private lands in 
the Rocky Mountain West has been rapidly increasing in recent years

[[Page 47538]]

and is expected to continue as people move to this area for its natural 
amenities (Hansen et al. 2002, p. 151). Infrastructure development may 
affect wildlife directly by eliminating habitats, or indirectly, by 
displacing animals from suitable habitats near developments.
    Wolverine home ranges generally do not occur near human 
settlements, and this separation is largely due to differential habitat 
selection by wolverines and humans (May et al. 2006, pp. 289-292; 
Copeland et al. 2007, p. 2211). In one study, wolverines did not 
strongly avoid developed habitat within their home ranges (May et al 
2006, p. 289). Wolverines may respond positively to human activity and 
developments that are a source of food. They scavenge food at dumps in 
and adjacent to urban areas, at trapper cabins, and at mines (LeResche 
and Hinman 1973 as cited in Banci 1994 p. 115; Banci 1994, p. 99). 
Based on the best available science, we conclude that wolverines do not 
avoid human development of the types that occur within suitable 
wolverine habitat.
    There is no evidence that wolverine dispersal is affected by 
infrastructure development. Linkage zones are places where animals can 
find food, shelter, and security while moving across the landscape 
between suitable habitats. Wolverines prefer to travel in habitat that 
is most similar to habitat they use for home-range establishment, i.e., 
alpine habitats that maintain snow cover well into the spring (Schwartz 
et al. 2009, p. 3227). Wolverines may move large distances in an 
attempt to establish new home ranges, but the probability of making 
such movements decreases with increased distance between suitable 
habitat patches, and the degree to which the characteristics of the 
habitat to be traversed diverge from preferred habitat in terms of 
climatic conditions (Copeland et al. 2010, entire; Schwartz et al. 
2009, p. 3230).
    The level of development in these linkage areas that wolverines can 
tolerate is unknown, but it appears that the current landscape does 
allow wolverine dispersal (Schwartz et al. 2009, Figures 4, 5; Moriarty 
et al. 2009, entire; Inman et al. 2009, pp. 22-28). For example, 
wolverine populations in the northern Rocky Mountains appear to be 
connected to each other at the present time through dispersal routes 
that correspond to habitat suitability (Schwartz et al. 2009, Figures 
4, 5).),
    Wolverines are capable of long-distance movements through variable 
and anthropogenically altered terrain, crossing numerous transportation 
corridors (Moriarty et al. 2009, entire; Inman et al. 2009, pp. 22-28). 
Wolverines are able to successfully disperse between habitats, despite 
the level of development that is currently taking place in the current 
range of the DPS (Copeland 1996, p. 80; Copeland and Yates 2006, pp. 
17-36; Inman et al. 2007a, pp. 9-10; Pakila et al. 2007, pp. 105-109; 
Schwartz et al. 2009, Figures 4, 5). Dispersal between populations is 
needed to avoid further reduction in genetic diversity; however, there 
is no evidence that human development and associated activities are 
preventing wolverine movements between suitable habitat patches. 
Rather, wolverine movement rates are limited by suitable habitat and 
proximity of suitable habitat patches, not the characteristics of the 
intervening unsuitable habitat (Schwartz et al. p. 3230).
Transportation Corridors
    Transportation corridors are places where transportation 
infrastructure and other forms of related infrastructure are 
concentrated together. Examples include interstate highways and high-
volume secondary highways. These types of highway corridors often 
include railroads; retail, industrial, and residential development; and 
electrical and other types of energy transmission infrastructure. 
Transportation corridors may affect wolverines if located in wolverine 
habitat or between habitat patches. If located in wolverine habitat, 
transportation corridors result in direct loss of habitat. Direct 
mortality due to collisions with vehicles is also possible (Packila et 
al. 2007, Table 1).
    The Trans Canada Highway at Kicking Horse Pass in southern British 
Columbia, an important travel corridor over the Continental Divide, has 
a negative effect on wolverine movement (Austin 1998, p. 30). 
Wolverines partially avoided areas within 100 m (328 ft) of the 
highway, and preferred to use distant sites (greater than 1,100 m 
(3,608 ft)). Wolverines that approached the highway to cross repeatedly 
retreated, and successful crossing occurred in only half of the 
attempts (Austin 1998, p. 30). Highway-related mortality was not 
documented in the study. Where wolverines did successfully cross, they 
used the narrowest portions of the highway right-of-way. A railway with 
minimal human activity, adjacent to the highway, had little effect on 
wolverine movements. Wolverines did not avoid, and even preferred, 
compacted, lightly used ski trails in the area. The extent to which 
avoidance of the highway may have affected wolverine vital rates or 
life history was not measured.
    In the tri-State area of Idaho, Montana, and Wyoming, most 
documented crossings of Federal or State highways were done by subadult 
wolverines making exploratory or dispersal movements (ranges of 
resident adults typically do not contain major roads) (Packila et al. 
2007, p. 105). Roads in the study area, typically two-lane highways or 
roads with less improvement, were not absolute barriers to wolverine 
movement. The individual wolverine that moved to Colorado from Wyoming 
in 2008 successfully crossed Interstate 80 in southern Wyoming (Inman 
et al. 2008, Figure 6). Wolverines in Norway successfully cross deep 
valleys that contain light human developments such as railway lines, 
settlements, and roads (Landa et al. 1998, p. 454). Wolverines in 
central Idaho avoided portions of a study area that contained roads, 
although this was possibly an artifact of unequal distribution of roads 
that occurred at low elevations and peripheral to the study site 
(Copeland et al. 2007, p. 2211). Wolverines frequently used un-
maintained roads for traveling during the winter, and did not avoid 
trails used infrequently by people or active campgrounds during the 
summer (Copeland et al. 2007, p. 2211).
    At both a site-specific and landscape scale, wolverine natal dens 
were located particularly distant from public (greater than 7.5 km (4.6 
mi)) and private (greater than 3 km (1.9 mi)) roads (May 2007, pp. 14-
31). Placement of dens away from public roads (and away from associated 
human-caused mortality) was a positive influence on successful 
reproduction (May 2007, pp. 14-31). Predictive, broad-scale habitat 
models, developed using historical records of wolverine occurrence, 
indicated that roads were negatively associated with wolverine 
occurrence (Rowland et al. 2003, p. 101). Although wolverines appear to 
avoid transportation corridors in their daily movements, studies of the 
few areas where transportation corridors are located in wolverine 
habitat leads us to conclude that the effects are most likely local in 
scale. There are no studies that address potential effects of 
transportation corridors in linkage areas (i.e., outside of wolverine 
habitat). In the few documented long-distance movements by wolverines, 
the animals successfully crossed transportation corridors (Inman et al. 
2009, Fig. 6). The available evidence indicates that dispersing 
wolverines can successfully cross transportation corridors.
Land Management
    Few effects to wolverines from land management actions such as 
grazing,

[[Page 47539]]

timber harvest, and prescribed fire have been documented. Wolverines in 
British Columbia used recently logged areas in the summer and moose 
winter ranges for foraging (Krebs et al. 2007, pp. 2189-2190). Males 
did not appear to be influenced strongly by the presence of roadless 
areas (Krebs et al. 2007, pp. 2189-2190). In Idaho, wolverines used 
recently burned areas despite the loss of canopy cover (Copeland 1996, 
p. 124).
    Intensive management activities such as timber harvest and 
prescribed fire do occur in wolverine habitat; however, for the most 
part, wolverine habitat tends to be located at high elevations and in 
rugged topography that is unsuitable for intensive timber management. 
Much of wolverine habitat is managed by the U.S. Forest Service or 
other Federal agencies and is protected from some practices or 
activities such as residential development. In addition, much of 
wolverine habitat within the contiguous United States is already in a 
management status such as wilderness or national park that provides 
some protection from management, industrial, and recreational 
activities. Wolverines are not thought to be dependent on specific 
vegetation or habitat features that might be manipulated by land 
management activities, nor is there evidence to suggest that land 
management activities are a threat to the conservation of the DPS.
Summary of Factor A
    At this time, we do not have sufficient information to make a 
reliable prediction about how wolverines are likely to respond to the 
effects of climate change. Wolverines have recently expanded in the 
North Cascades and the northern Rocky Mountains from sources in Canada, 
and are continuing to expand into suitable habitat not currently 
occupied and/or occupied by a few individuals, including into Colorado, 
California, Wyoming, and Utah. New information estimated that current 
population size is approximately half of capacity (Inman et al. 2013), 
confirming that continued population growth and expansion is possible 
and even likely (Aubry et al. 2007, p. 2151).
    There is strong support for the existence of an obligate 
relationship between wolverines and deep spring snow at the den site. 
However, available information suggests that availability of den sites 
is not currently limiting wolverines, and we do not have sufficient 
information to predict if and when this will occur in the future. 
Furthermore, the importance of the relationship between wolverines and 
snow at the broader home-range and DPS-range scales is uncertain. That 
is, whether deep snow is required by wolverines outside of their needs 
at the scale of the individual den site is not certain.
    There is significant evidence that the climate within the range of 
the wolverine is warming, which will likely impact both snowfall and 
snow persistence. However, at this time, we do not have the sufficient 
resolution of predictive climate models nor sufficient certainty in 
those models and the results from them to make reasonably certain 
conclusions about the specific response or sensitivity of wolverines to 
predicted changes in amount and persistence of snowfall. Human 
activities, including dispersed recreation activities, infrastructure, 
and the presence of transportation corridors, occur in occupied 
wolverine habitat. However, the alpine and subalpine habitats preferred 
by wolverine typically receive little human use relative to lower 
elevation habitats. The majority of wolverine habitat (over 90 percent) 
occurs within U.S. Forest Service and National Park Service lands that 
are subject to activities, but usually not direct habitat loss to 
infrastructure development. The best available science leads us to 
determine that human activities and developments do not pose a current 
threat to wolverines in the contiguous United States.
    Wolverines coexist with some modification of their environment, as 
wilderness characteristics such as complete lack of motorized use or 
any permanent human presence are likely not critical for maintenance of 
populations. It is clear that wolverines coexist with some level of 
human disturbance and habitat modification.
    We know of no examples where human activities such as dispersed 
recreation have occurred at a scale that could render a large enough 
area unsuitable so that a wolverine home range would be likely to be 
rendered unsuitable or unproductive. Given the large size of home 
ranges used by wolverine, most human activities affect such a small 
portion that negative effects to individuals are unlikely. These 
activities do not occur at a scale that is likely to have population-
level effects to wolverine.
    Little scientific or commercial information exists regarding 
effects to wolverines from development or human disturbances associated 
with them. What little information does exist suggests that wolverines 
can adjust to moderate habitat modification, infrastructure 
development, and human disturbance. In addition, large amounts of 
wolverine habitat are protected from human disturbances and 
development, either legally through wilderness and National Park 
designation, or by being located at remote and high-elevation sites. 
Therefore, wolverines are afforded a relatively high degree of 
protection from the effects of human activities by the nature of their 
habitat. Wolverines are known to successfully disperse long distances 
between habitats through human-dominated landscapes and across 
transportation corridors. The current level of residential, industrial, 
and transportation development in the western United States does not 
appear to have precluded the long-distance dispersal movements that 
wolverines require for maintenance of genetic diversity. We do not have 
information to suggest that future levels of residential, industrial, 
and transportation development would be a significant conservation 
concern for the DPS.
    In summary, we do not have the sufficient information to make a 
reliable prediction about how wolverines are likely to respond to 
impacts to habitat that may result from climate change and whether such 
habitat changes will pose a threat in the future. Additionally, the 
best available scientific and commercial information does not indicate 
that other potential stressors such as land management, recreation, 
infrastructure development, and transportation corridors pose a threat 
to the DPS.

Factor B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    Over much of recent history, trapping has been a primary cause of 
wolverine mortality (Banci 1994, p. 108; Krebs et al. 2004, p. 497; 
Lofroth and Ott 2007, pp. 2196-2197; Squires et al. 2007, p. 2217). 
Unregulated trapping is believed to have played a role in the 
historical decline of wolverines in North America in the late 1800s and 
early 1900s (Hash 1987, p. 580). Wolverines are especially vulnerable 
to targeted trapping and predator reduction campaigns due to their 
habit of ranging widely in search of carrion, bringing them into 
frequent contact with poison baits and traps (Copeland 1996, p. 78; 
Inman et al. 2007a, pp. 4-10; Packila et al. 2007, p. 105; Squires et 
al. 2007, p. 2219).
    A study in British Columbia determined that, under a regulated 
trapping regime, trapping mortality in 15 of 71 wolverine population 
units was unsustainable, and that populations in those unsustainable 
population units were dependent on immigration from neighboring 
populations or untrapped refugia (Lofroth and Ott 2007, pp. 2197-2198). 
Similarly, in southwestern Montana, legal trapping in isolated

[[Page 47540]]

mountain ranges accounted for 64 percent of documented mortality and 
reduced the local wolverine subpopulation (Squires et al. 2007, pp. 
2218-2219). The observed harvest levels, which included two pregnant 
females in a small mountain range, could have significant negative 
effects on a small subpopulation (Squires et al. 2007, p. 2219). 
Harvest refugia, such as jurisdictions with closed seasons, national 
parks, and large wilderness areas, are important to wolverine 
persistence on the landscape because they can serve as sources of 
surplus individuals to bolster trapped populations (Squires et al. 
2007, p. 2219; Krebs and Ott 2004, p. 500). Due to their large space 
requirements, wolverine population refuges must be large enough to 
provide protection from harvest mortality, and complete protection is 
only available for wolverines whose entire home range occurs within 
protected areas. Glacier National Park, though an important refuge for 
a relatively robust population of wolverines, was still vulnerable to 
trapping because most resident wolverines' home ranges extended into 
large areas outside the park (Squires et al. 2007, p. 2219). It is 
likely that the larger scale refuges provided by the States of Idaho 
and Wyoming (which do not permit wolverine trapping) provide wolverine 
habitat that is fully protected from legal harvest in Montana; however, 
wolverines with home ranges that partially overlap Montana and 
dispersers that move into Montana would be vulnerable to harvest. Due 
to the restrictive, low level of harvest now allowed by Montana, the 
number of affected wolverines would be correspondingly small.
    Despite the impacts of trapping on wolverines in the past, trapping 
is no longer a risk factor within most of the wolverine's range in the 
contiguous United States. Montana is the only State where wolverine 
trapping is still legal. Before 2004, average wolverine harvest was 
10.5 wolverines per year. Due to preliminary results of the study 
reported in Squires et al. (2007, pp. 2213-2220), the Montana 
Department of Fish, Wildlife, and Parks adopted new regulations for the 
2004-2005 trapping season that divided the State into three units, with 
the goal of spreading the harvest more equitably throughout the State.
    For the 2008-2009 trapping season, the Montana Department of Fish, 
Wildlife, and Parks adjusted its wolverine trapping regulations again 
to further increase the geographic control on harvest to prevent 
concentrated trapping in any single area, and to completely stop 
trapping in isolated mountain ranges where small populations are most 
vulnerable (Montana Department of Fish Wildlife and Parks 2010, pp. 8-
11). Their new regulations spread harvest across three geographic units 
(the Northern Continental Divide area, the Greater Yellowstone area, 
and the Bitterroot Mountains), and established a Statewide limit of 
five wolverines. From 2008 until 2012 wolverine take averaged 3 
wolverines annually (Montana Department of Fish Wildlife and Parks 
2010, pp. 8-11; Brian Giddings 2012, pers. comm.), with reduced harvest 
being due to season closure rather than lack of wolverines. The size of 
the wolverine population subjected to trapping in this area is not 
known precisely but is likely not more than about 300 animals in states 
of Montana, Idaho, and Wyoming combined (Inman et al. 2013). On 
November 30, 2012, a district court judge granted a temporary 
restraining order that blocked the opening of Montana's wolverine 
trapping season (Case No. BDV-2012-868). That restraining order remains 
in place and the season remains closed.
    The Montana Department of Fish, Wildlife, and Parks conduct yearly 
furbearer monitoring using track surveys. These surveys involve 
snowmobiling along transect routes under good tracking conditions and 
visually identifying all carnivore tracks encountered. The protocol 
does not use verification methods such as DNA collection or camera 
stations to confirm identifications. Consequently, misidentifications 
are likely to occur. Given the relative rarity of wolverines and the 
relative abundance of other species with which they may be confused, 
such as bobcats (Lynx rufus), Canada lynx (Lynx canadensis), and 
mountain lions (Felis concolor), lack of certainty of identifications 
of tracks makes it highly likely that the rare species is 
overrepresented in unverified tracking records (McKelvey et al. 2008, 
entire). The Montana Department of Fish, Wildlife, and Parks wolverine 
track survey information does not meet our standard for reliability, 
and we have not relied on this information in this analysis.
    Montana wolverine populations have rebounded from historic lows in 
the early 1900s while at the same time being subjected to regulated 
trapping (Aubry et al. 2007, p. 2151; Montana Department of Fish, 
Wildlife, and Parks 2007, p. 1). In fact, much of the wolverine 
expansion that we have described above took place under less 
restrictive (i.e., higher harvest levels) harvest regulations than are 
in place today. The extent to which wolverine population growth has 
occurred in Montana as a result of within-Montana population growth, 
versus population growth attributable to surrounding States where 
wolverines are not trapped (i.e., population growth driven by the 
entire metapopulation versus just the portion of the metapopulation 
found in Montana), is unknown.
    We reviewed the current levels of incidental trapping (i.e., 
capture in traps set for species other than wolverine) and impacts on 
wolverines. In the 2008-2009 trapping season, two wolverines were 
incidentally killed in traps set for other species in Beaverhead and 
Granite Counties, Montana (Montana Fish, Wildlife, and Parks 2010, p. 
2). These two mortalities occurred within the portion of southwestern 
Montana that is currently closed to legal wolverine trapping to ensure 
that wolverines are not unsustainably harvested in this area of small, 
relatively isolated mountain ranges. More recently, a wolverine was 
trapped incidentally and released unharmed in December 2013, and 
another was incidentally killed in January 2014 by a trap set for other 
species (Giddings 2014, pers. comm.). Idaho Department of Fish and Game 
records show that since 1965, 14 wolverines have been incidentally 
trapped during the Idaho furbearer season, equating to an average of 
0.29 wolverines incidentally trapped annually. Eight of these 
incidental catches were released alive, and 6 resulted in confirmed 
mortality. This count includes 4 wolverines incidentally trapped during 
the 2013-2014 furbearer season (3 released alive; 1 mortality) (Idaho 
Department of Fish and Game 2014, p. 26). The U.S. Department of 
Agriculture's Wildlife Services trapped three wolverines (one each in 
2004, 2005, and 2010) incidental to trapping wolves involved in 
livestock depredations. One of these sustained severe injuries and was 
euthanized. The other two were released without visible injury. Another 
wolverine was trapped in Wyoming in 2006 outside of the expected range 
for wolverine (Lanka 2014, pers. comm.). This animal was released 
unharmed (Inman 2012, pers. comm.). The three documented mortalities 
are possibly locally significant for wolverines in these areas because 
local populations in each of the mountain ranges are small and 
relatively isolated from nearby source populations.
Summary of Factor B
    Legal wolverine harvest occurs in one state, Montana, within the 
range of the DPS. The extent to which this harvest

[[Page 47541]]

affects populations occurring outside of Montana is unknown. However, 
the State of Montana contains much of the habitat and wolverines that 
exist in the current range of the DPS, and regulates trapping to reduce 
the impact of harvest on wolverine populations. Incidental harvest also 
occurs within the range of the DPS; however, the level of mortality 
from incidental trapping appears to be low.
    The current known level of incidental trapping mortality is low. We 
note that it is unknown whether or not increased trapping of wolves 
associated with wolf trapping regulations recently approved by the 
States of Idaho and Montana would be likely to result in increased 
incidental trapping of wolverines. Idaho began its wolf trapping 
program in the winter of 2011-2012, and Montana began theirs in the 
winter of 2012-2013. These wolf trapping activities are relatively new 
in the DPS area, and we do not yet have reliable information on the 
level of incidental take of wolverines that may result from them.
    Based on the best scientific and commercial information available, 
we conclude that trapping, including known rates of incidental trapping 
in Montana and Idaho, result in a small number of wolverine mortalities 
each year and that this level of mortality by itself is not a threat to 
the wolverine DPS.

Factor C. Disease or Predation

    No information is currently available on the potential effects of 
disease on wild wolverine populations. Wolverines are sometimes killed 
by wolves (Canis lupus), black bears (Ursus americanus), and mountain 
lions (Burkholder 1962, p. 264; Hornocker and Hash 1981, p. 1296; 
Copeland 1996, pp. 44-46; Inman et al. 2007d, p. 89). In addition, 
wolverine reproductive dens are likely subject to predation, although 
so few dens have been discovered in the contiguous U.S. that 
determining the intensity of this predation is not possible.
Summary of Factor C
    We have no information to suggest that wolverine mortality from 
predation and disease is above natural or sustainable levels. The best 
scientific and commercial information available indicates that disease 
or predation is not a threat to the DPS now or likely to become so in 
the future.

Factor D. Inadequacy of Existing Regulatory Mechanisms

    Our interpretation of the Act for assessing regulatory mechanisms 
under Factor D is to evaluate the inadequacy of existing regulatory 
mechanisms in the context of how they address the threats identified 
for the DPS or its habitat under Factors A, B, C, or E. Based on the 
conclusion that effects related to climate change are not a threat, and 
the fact that other threats cited in the proposed rule were considered 
threats only in light of the effects of climate change, we have 
determined that there are no threats to the wolverine under any of the 
factors. There were two areas, however, where regulatory mechanisms 
contributed to our conclusion that risk factors were not threats: 
Regulations under the Wilderness Act and trapping regulations in 
Montana.
The Wilderness Act
    The U.S. Forest Service and National Park Service both manage lands 
designated as wilderness areas under the Wilderness Act of 1964 (16 
U.S.C. 1131-1136). Within these areas, the Wilderness Act states the 
following: (1) New or temporary roads cannot be built; (2) there can be 
no use of motor vehicles, motorized equipment, or motorboats; (3) there 
can be no landing of aircraft; (4) there can be no other form of 
mechanical transport; and (5) no structure or installation may be 
built. A large amount of suitable wolverine habitat, about 28 percent 
for the States of Montana, Idaho, and Wyoming, occurs within Federal 
wilderness areas in the United States (Inman, 2007b, pers. comm.). As 
such, a large proportion of existing wolverine habitat is protected 
from direct loss or degradation by the prohibitions of the Wilderness 
Act.
    Wilderness areas provide protection to wolverines by making access 
to wolverine habitats difficult, especially in winter. Wolverine 
habitats are characterized by deep snow and cold conditions in the 
winter time. Access to these areas is restricted to non-motorized 
users. This makes it extremely difficult to pursue trapping activities 
in wilderness that may purposefully target wolverines or incidentally 
capture them.
Montana Trapping Regulations
    Before 2004, the Montana Department of Fish, Wildlife, and Parks 
regulated wolverine harvest through the licensing of trappers, a bag 
limit of one wolverine per year per trapper, and no Statewide limit. 
Under this management, average wolverine harvest was 10.5 wolverines 
per year. Due to preliminary results of the study reported in Squires 
et al. (2007, pp. 2213-2220), Montana Department of Fish, Wildlife, and 
Parks adopted new regulations for the 2004-2005 trapping season that 
divided the State into three units with the goal of spreading the 
harvest more equitably among available habitat. In 2008, Montana 
Department of Fish, Wildlife, and Parks further refined their 
regulations to prohibit trapping in isolated mountain ranges, and 
reduced the overall Statewide harvest to five wolverines with a 
Statewide female harvest limit of three. Due to a court-issued 
restraining order issued in November 2012, the Montana trapping season 
on wolverines was blocked and remains closed. Under Factor B, above, we 
concluded that trapping, including known rates of incidental trapping 
in Montana and other parts of the DPS, is not a threat to the wolverine 
DPS.

Factor E. Other Natural or Manmade Factors Affecting Its Continued 
Existence

Small Population Size
    Population ecologists use the concept of a population's 
``effective'' size as a measure of the proportion of the actual 
population that contributes to future generations (for a review of 
effective population size, see Schwartz et al. 1998, entire). In a 
population where all of the individuals contribute offspring equally, 
effective population size would equal true population size, referred to 
as the population census size. For populations where contribution to 
the next generations is often unequal, effective population size will 
be smaller than the census size. The smaller the effective population 
size, the more reproduction in each generation is dominated by a few 
individuals in each generation. For wolverines it is likely that 
individuals occupying high-quality home ranges are better able to 
reproduce. Therefore, mature males and females that are successful at 
acquiring and defending a territory may dominate reproduction. Another 
contributing factor that reduces effective population size is the 
tendency in wolverines for a few males to monopolize the reproduction 
of several females, reducing reproductive opportunities for other 
males. Although this monopolization is a natural feature of wolverine 
life-history strategy, it can lead to lower effective population size 
and reduce population viability by reducing genetic diversity. The 
effective population is not static; members of the effective population 
in one year may lose this status in the following year and possibly 
regain it again later depending on their reproductive success. When 
members of the effective population are lost, it is likely that their 
territories are quickly filled by younger individuals

[[Page 47542]]

who may not have been able to secure a productive territory previously.
    Effective population size is important because it determines rates 
of loss of genetic variation and the rate of inbreeding. Populations 
with small effective population sizes show reductions in population 
growth rates and increases in extinction probabilities when genetic 
diversity is low enough to lead to inbreeding depression (Leberg 1990, 
p. 194; Jimenez et al. 1994, pp. 272-273; Newman and Pilson 1997, p. 
360; Saccheri et al. 1998, p. 492; Reed and Bryant 2000, p. 11; 
Schwartz and Mills 2005, p. 419; Hogg et al. 2006, pp. 1495, 1498; 
Allendorf and Luikart 2007, pp. 338-342). Franklin (1980, as cited in 
Allendorf and Luikart 2007, p. 359) proposed an empirically based rule 
suggesting that for short-term (a few generations) maintenance of 
genetic diversity, effective population size should not be less than 
50. For long-term (hundreds of generations) maintenance of genetic 
diversity, effective population size should not be less than 500 
individuals (for appropriate use of this rule and its limitations see 
Allendorf and Luikart 2007, pp. 359-360); others propose that even 
higher numbers are required. Each wolverine subpopulation within the 
contiguous United States would need an estimated 400 breeding pairs, or 
1 to 2 effective migrants per generation to meet this threshold 
(Cegelski et al. 2006, p. 209). Long-term connectivity to the reservoir 
of genetic resources in the Canadian population of wolverines will 
likely be required for the long-term genetic health of the DPS (Traill 
et al. 2010, p. 32; Allendorf and Luikart 2007, pp. 359-360). Since the 
proposed rule published (February 4, 2013), Inman et al. (2013) 
published an estimated available habitat capacity to be approximately 
644 wolverines (95 percent CI = 506-1881) and estimated that current 
population size is currently approximately half of capacity. Given the 
life history of wolverines that includes high inequality of 
reproductive success and a metapopulation of semi-isolated 
subpopulations, effective population sizes would likely never reach 
even 100 individuals at full habitat occupancy, as this would suggest a 
census population of over 1,000. In this case, population connectivity 
exchange with the larger Canadian/Alaskan population would likely be 
required for long-term genetic health of the DPS.
    Wolverine effective population size in the northern Rocky 
Mountains, which is the largest extant population in the contiguous 
United States, is low and is below what is thought necessary for short-
term maintenance of genetic diversity. Estimates for effective 
population size for wolverines in the northern Rocky Mountains averaged 
35 (credible limits = 28-52) (Schwartz et al. 2009, p. 3226). This 
study excluded the small population from the Crazy and Belt Mountains 
(hereafter ``CrazyBelts'') as they may be an isolated population, which 
could bias the estimate using the methods of Tallmon et al. (2007, 
entire). Measures of the effective population sizes of the other 
populations in the contiguous United States have not been completed, 
but given their small census sizes, their effective sizes are expected 
to be smaller than for the northern Rocky Mountains population. Thus, 
wolverine effective population sizes are very low. To date, no adverse 
effects of the lower genetic diversity of the contiguous U.S. DPS of 
wolverines have been documented. Therefore, we conclude that effective 
population size estimates for wolverines do not suggest that small 
population size is currently a threat to the DPS, but they do suggest 
that populations are low enough that they could be vulnerable to loss 
of genetic diversity in the future.
    Wolverines in the contiguous United States are thought to be 
derived from a recent recolonization event after they were extirpated 
from the area in the early 20th century (Aubry et al. 2007, Table 1). 
Consequently, wolverine populations in the contiguous United States 
have reduced genetic diversity relative to larger Canadian populations 
as a result of founder effects or inbreeding (Schwartz et al. 2009, pp. 
3228-3230). Wolverine effective population size in the northern Rocky 
Mountains was estimated to be 35 (Schwartz et al. 2009, p. 3226) and is 
below what is thought to be adequate for short-term maintenance of 
genetic diversity. Loss of genetic diversity can lead to inbreeding 
depression and is associated with increased risk of extinction 
(Allendorf and Luikart 2007, pp. 338-343). Small effective population 
sizes are caused by small actual population size (census size), or by 
other factors that limit the genetic contribution of portions of the 
population, such as polygamous mating systems. Populations may increase 
their effective size by increasing census size or by the regular 
exchange of genetic material with other populations through 
interpopulation mating.
    The concern with the low effective population size was highlighted 
in a recent analysis that determined that, without immigration from 
other wolverine populations, at least 400 breeding pairs would be 
necessary to sustain the long-term genetic viability of the northern 
Rocky Mountains wolverine population (Cegelski et al. 2006, p. 197). 
However, the entire population is likely only 250 to 300 (Inman 2010b, 
pers. comm.), with a substantial number of these being unsuccessful 
breeders or nonbreeding subadults (i.e., part of the census population, 
but not part of the effective population).
    Genetic studies demonstrate the essential role that genetic 
exchange plays in maintaining genetic diversity in small wolverine 
populations. Genetic drift has already occurred in subpopulations of 
the contiguous United States: Wolverines here contained 3 of 13 
haplotypes found in Canadian populations (Kyle and Strobeck 2001, p. 
343; Cegelski et al. 2003, pp. 2914-2915; Cegelski et al. 2006, p. 208; 
Schwartz et al. 2007, p. 2176; Schwartz et al. 2009, p. 3229). The 
haplotypes found in these subpopulations were a subset of those in the 
larger Canadian population, indicating that genetic drift had caused a 
loss of genetic diversity. One study found that a single haplotype 
dominated the northern Rocky Mountain wolverine population, with 71 of 
73 wolverines sampled expressing that haplotype (Schwartz et al. 2007, 
p. 2176). The reduced number of haplotypes indicates not only that 
genetic drift has occurred but also some level of genetic separation; 
if these populations were freely interbreeding, they would share more 
haplotypes (Schwartz et al. 2009, p. 3229). The reduction of haplotypes 
is likely a result of the fragmented nature of wolverine habitat in the 
United States and is consistent with an emerging pattern of reduced 
genetic variation at the southern edge of the range documented in a 
suite of boreal forest carnivores (Schwartz et al. 2007, p. 2177). 
However, as mentioned above, no adverse effects of the lower genetic 
diversity of the contiguous U.S. DPS of wolverines have been 
documented.
    Immigration of wolverines from Canada is not likely to bolster the 
genetic diversity of wolverines in the contiguous United States. There 
is an apparent lack of connectivity between wolverine populations in 
Canada and the United States based on genetic data (Schwartz et al. 
2009, pp. 3228-3230). The apparent loss of connectivity between 
wolverines in the northern Rocky Mountains and Canada prevents the 
influx of genetic material needed to maintain or increase the genetic 
diversity in the contiguous United States. The continued loss of 
genetic diversity may lead to inbreeding depression, potentially 
reducing the DPS ability to persist through reduced

[[Page 47543]]

reproductive output or reduced survival. Currently, the cause for this 
lack of connectivity is uncertain. Wolverine habitat appears to be 
well-connected across the border region (Copeland et al. 2010, Figure 
2), and there are few manmade obstructions such as transportation 
corridors or alpine developments. However, this lack of genetically 
detectable connectivity may be related to harvest management in 
southern Canada.
Summary of Factor E
    Small population size and resulting inbreeding depression are 
potential, though as-yet undocumented, threats to wolverines in the 
contiguous United States. There is good evidence that genetic diversity 
is lower in wolverines in the DPS than it is in the more contiguous 
habitat in Canada and Alaska. The significance of this lower genetic 
diversity to wolverine conservation is unknown. We do not discount the 
possibility that loss of genetic diversity could be negatively 
affecting wolverines now and could continue to do so in the future. It 
is important to point out, however, that wolverine populations in the 
DPS area are thought to be the result of colonization events that have 
occurred since the 1930s. Such recent colonizations by relatively few 
individuals and subsequent population growth are likely to have 
resulted in founder effects, which could contribute to low genetic 
diversity. The effect of small population sizes and low genetic 
diversity may become more significant if populations become smaller and 
more isolated.
    Based on the best scientific and commercial information available 
we conclude that demographic stochasticity and loss of genetic 
diversity due to small effective population sizes is not a threat to 
the wolverine DPS. In the proposed listing rule, we concluded that 
demographic stochasticity and loss of genetic diversity due to small 
effective population sizes were threats to wolverines only when 
considered cumulatively with habitat loss due to climate change. Since 
we no longer find that habitat loss due to climate change is a threat 
to the wolverine DPS, we also no longer find that demographic 
stochasticity and loss of genetic diversity due to small effective 
population sizes are threats when considered cumulatively with habitat 
loss due to climate change.
Synergistic Interactions Between Threat Factors
    A species may be affected by more than one factor in combination. 
Within the preceding review of the five threat factors, we discussed 
potential threats that may have interrelated impacts on wolverines. Our 
analysis did not find any significant effects to wolverines. However, 
we recognize that multiple stressors acting in combination have greater 
potential to affect wolverines than each source alone. Thus, we 
consider how the combination of these stressors may affect wolverines.
    In our proposed listing rule (74 FR 7885-7886), we identified 
stressors that became threats to wolverines when operating in concert 
with the effects of climate change. Those secondary threats included 
genetic and demographic effects of small population size and the 
effects of harvest, both intentional permitted trapping and incidental 
trapping as non-target species. Given new information highlighting the 
uncertainty of how the effects of climate change will impact the 
wolverine DPS, we did not identify the effects of climate change as 
posing a risk of extinction to the DPS, and, at this time, we therefore 
conclude that the identified secondary factors do not rise to the level 
of a threat to the DPS when considered in combination with the effects 
of climate change. We are uncertain of how wolverines will respond to 
the effects of climate change on their habitat and the resulting 
population persistence, and do not conclude that demographic 
stochasticity and loss of genetic diversity due to small population 
size will be realized. Regarding harvest, we do not find the limited 
legal harvest currently occurring in Montana (<= 5 animals per year) to 
be a threat as the population appears to have continued to increase 
while sustaining this level of legal take. Regarding incidental take 
associated with legal harvest activities, we also do not find it rises 
to the level of a threat to the DPS because documented incidental take 
is extremely low and wolverines have seemingly increased with this 
potential mortality source in existence. Wolverine populations have 
been expanding in the DPS area since the early 20th century, when they 
were likely at or near zero (Aubry et al. 2007, p. 2151). Given this 
ongoing expansion in the DPS area and the lack of identified threats, 
we do not find any combination of factors to be a threat at this time.

Determination

    As required by the Act, we considered the five factors in assessing 
whether the wolverine meets the definition of an endangered or a 
threatened species. We examined the best scientific and commercial 
information available regarding the present and future threats faced by 
the DPS. Based on our review of the best available scientific and 
commercial information, we find that the current and future factors 
affecting the wolverine are not of sufficient imminence, intensity, or 
magnitude to indicate that the wolverine is in danger of extinction 
(endangered), or likely to become endangered within the foreseeable 
future (threatened), throughout all or a significant portion of its 
range. Therefore, the wolverine DPS does not meet the definition of an 
endangered or a threatened species, and we are withdrawing the proposed 
rule to list the wolverine as a threatened species. Our rationale for 
this determination is outlined below.
    Our proposed rule to list the wolverine as a threatened species 
identified one primary threat to the wolverine (effects of climate 
change on habitat) and other threats as secondary, only rising to the 
level of a threat to the extent that they may work in concert with 
climate change impacts to affect the status of the DPS. The reduction 
of persistent spring snow due to climate change was cited as the 
specific threat. The degree to which wolverine populations will be 
impacted by a change in the amount or extent of deep snow limiting the 
availability of year round habitat and den sites is the fundamental 
question that informs whether the DPS is likely to become an endangered 
species in the foreseeable future. Our original conclusion was that 
such a change in climate would in fact cause habitat loss, den site 
loss, and ultimately population impacts leading to the wolverine being 
likely to become an endangered species within the foreseeable future. 
After further consideration, and with input from peer review, public 
comments, and the expert panel workshop, we no longer conclude that 
impacts from climate change pose a risk of extinction to the wolverine 
DPS for the following reasons:
    (1) Considering all of the information we have received and 
summarized, we have evidence that wolverines are expanding both within 
the area currently inhabited by wolverines as well as into suitable 
habitat not currently occupied and/or occupied with a few individuals. 
Recent evidence suggests that there is suitable habitat available 
within the contiguous United States to support a wolverine population 
twice as large as that at present. Even under conditions of future 
reduced snowpack as a consequence of climate change, sufficient habitat 
will likely remain to maintin the wolverine population at the current 
level of abundance.

[[Page 47544]]

    (2) There is strong support for the existence of an obligate 
relationship between wolverines and deep spring snow at the den site; 
however, available information suggests that den sites are not 
currently limiting wolverines, and we do not have sufficient 
information to predict if and when any limitation will occur in the 
future. Additionally, support for the obligate relationship between 
wolverine and deep snow at an individual wolverine's home range or the 
DPS' range in general is lacking. That is, we do not have evidence to 
suggest that deep snow is required by wolverines throughout their home 
ranges, beyond the level of the individual den site.
    (3) There is significant evidence that the climate within the 
larger range of the wolverine is warming, which will no doubt have 
impacts on both snowfall and snow persistence. However, at this time, 
we do not have sufficient resolution of predictive climate models nor 
sufficient certainty in those models and the results from them to 
understand the specific response or sensitivity of wolverines to 
predicted changes in the amount and persistence of snowfall at the 
scale of specific wolverine den sites. Uncertainties in the models, the 
effects that could occur, and the potential associated responses in the 
species include the following:
    a. McKelvey et al. (2011) is the most sophisticated analysis of the 
impacts of climate change at a scale specific to wolverine; however, 
the scale is not fine enough to deal with the site specific 
characteristics of wolverine dens.
    b. Wolverine dens typically occur at high elevation and on north-
facing slopes. The conclusion of habitat loss for wolverines based on 
loss of spring snow was based on analysis of snow at the overall range 
of wolverine and did not scale down to areas specifically selected by 
wolverines for den locations.
    c. There is uncertainty in the ability of the models to predict 
both snowfall amounts and/or persistence in areas most important for 
critical wolverine life stages (i.e., denning).
    d. Although snow cover may be reduced in the future, due to the 
expansive home ranges of female wolverines and availability of multiple 
potential den sites, there is no evidence to suggest that den sites for 
wolverines will become a limiting factor in the foreseeable future.
    e. It is possible that, in response to the effects of climate 
change, subpopulations may become increasingly isolated from each other 
in the future. However, wolverines are known to regularly move long 
distances through unsuitable habitat, suggesting that individuals will 
likely be able to maintain connectivity between occupied areas.
    While we understand the basis of the predictions in the McKelvey et 
al. (2011) model, for the reasons outlined in our analysis under Factor 
A, we do not accept that a loss of snow across the range of the 
wolverine will result in a commensurate reduction in suitable wolverine 
habitat. Furthermore, due to the uncertainty of climate models, and the 
fact that we do not have the fine-scale modeling available to make 
accurate predictions about the continued availability of den sites, in 
our best professional judgment, we no longer agree with the conclusion 
about wolverine habitat loss that formed the basis of the proposed 
rule. Although climate change effects are expected to result in the 
loss of some wolverine habitat, we have no data to inform us as to 
whether or how these projected effects may affect the viability of 
wolverine populations. Our most recent review of the best available 
information indicates that even in the face of the effects of climate 
change, sufficient habitat will likely remain to support wolverines in 
the contiguous U.S. at numbers at the very least roughly equal to those 
estimated to exist today. Thus, even under future projected 
environmental conditions, we do not have data to suggest that wolverine 
populations in the contiguous United States are likely to experience 
significant declines, such that they are likely to become in danger of 
extinction within the foreseeable future. Accordingly, we no longer 
find that listing the wolverine DPS as a threatened species is 
warranted. We hereby withdraw the proposed rule to list the wolverine 
DPS as a threatened species under the Act (78 FR 7864; February 4, 
2013), and find that the DPS is not warranted for listing as endangered 
or threatened. Accordingly, we also withdraw the associated proposed 
rule under section 4(d) of the Act contained in the proposed listing 
rule (78 FR 7864; February 4, 2013) and withdraw the proposed 
nonessential population designation for the southern Rocky Mountains 
States (78 FR 7890; February 4, 2013).
    We will continue to monitor the status of the DPS and evaluate any 
other information we receive. Additional information will continue to 
be accepted on all aspects of the DPS. If at any time data indicate 
that the protective status under the Act should be provided or if there 
are new threats or increasing stressors that rise to the level of a 
threat, we can initiate listing procedures, including, if appropriate, 
emergency listing pursuant to section 4(b)(7) of the Act.

Significant Portion of the Range

    Under the Act and our implementing regulations, a species may 
warrant listing if it is an endangered or a threatened species 
throughout all or a significant portion of its range. The Act defines 
``endangered species'' as any species which is ``in danger of 
extinction throughout all or a significant portion of its range,'' and 
``threatened species'' as any species which is ``likely to become an 
endangered species within the foreseeable future throughout all or a 
significant portion of its range.'' The term ``species'' includes ``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.'' We published a final policy interpretating 
the phrase ``Significant Portion of its Range'' (SPR) (79 FR 37578). 
The final policy states that (1) if a species is found to be an 
endangered or a threatened species throughout a significant portion of 
its range, the entire species is listed as an endangered or a 
threatened species, respectively, and the Act's protections apply to 
all individuals of the species wherever found; (2) a portion of the 
range of a species is ``significant'' if the species is not currently 
an endangered or a threatened species throughout all of its range, but 
the portion's contribution to the viability of the species is so 
important that, without the members in that portion, the species would 
be in danger of extinction, or likely to become so in the foreseeable 
future, throughout all of its range; (3) the range of a species is 
considered to be the general geographical area within which that 
species can be found at the time FWS or NMFS makes any particular 
status determination; and (4) if a vertebrate species is an endangered 
or a threatened species throughout an SPR, and the population in that 
significant portion is a valid DPS, we will list the DPS rather than 
the entire taxonomic species or subspecies.
    The SPR policy is applied to all status determinations, including 
analyses for the purposes of making listing, delisting, and 
reclassification determinations. The procedure for analyzing whether 
any portion is an SPR is similar, regardless of the type of status 
determination we are making. The first step in our analysis of the 
status of a species is to determine its status throughout all of its 
range. If we determine that the species is in danger of extinction, or 
likely to become so in

[[Page 47545]]

the foreseeable future, throughout all of its range, we list the 
species as an endangered (or threatened) species and no SPR analysis 
will be required. If the species is neither an endangered nor a 
threatened species throughout all of its range, we determine whether 
the species is an endangered or a threatened species throughout a 
significant portion of its range. If it is, we list the species as an 
endangered or a threatened species, respectively; if it is not, we 
conclude that listing the species is not warranted.
    When we conduct an SPR analysis, we first identify any portions of 
the species' range that warrant further consideration. The range of a 
species can theoretically be divided into portions in an infinite 
number of ways. However, there is no purpose to analyzing portions of 
the range that are not reasonably likely to be significant and either 
an endangered or a threatened species. To identify only those portions 
that warrant further consideration, we determine whether there is 
substantial information indicating that (1) the portions may be 
significant and (2) the species may be in danger of extinction in those 
portions or likely to become so within the foreseeable future. We 
emphasize that answering these questions in the affirmative is not a 
determination that the species is an endangered or a threatened species 
throughout a significant portion of its range--rather, it is a step in 
determining whether a more detailed analysis of the issue is required. 
In practice, a key part of this analysis is whether the threats are 
geographically concentrated in some way. If the threats to the species 
are affecting it uniformly throughout its range, no portion is likely 
to warrant further consideration. Moreover, if any concentration of 
threats apply only to portions of the range that clearly do not meet 
the biologically based definition of ``significant'' (i.e., the loss of 
that portion clearly would not be expected to increase the 
vulnerability to extinction of the entire species), those portions will 
not warrant further consideration.
    If we identify any portions that may be both (1) significant and 
(2) endangered or threatened, we engage in a more detailed analysis to 
determine whether these standards are indeed met. The identification of 
an SPR does not create a presumption, prejudgment, or other 
determination as to whether the species in that identified SPR is an 
endangered or a threatened species. We must go through a separate 
analysis to determine whether the species is an endangered or a 
threatened species in the SPR. To determine whether a species is an 
endangered or a threatened species throughout an SPR, we will use the 
same standards and methodology that we use to determine if a species is 
an endangered or a threatened species throughout its range.
    Depending on the biology of the species, its range, and the threats 
it faces, it may be more efficient to address the ``significant'' 
question first, or the status question first. Thus, if we determine 
that a portion of the range is not ``significant,'' we do not need to 
determine whether the species is an endangered or a threatened species 
there; if we determine that the species is not an endangered or a 
threatened species in a portion of its range, we do not need to 
determine if that portion is ``significant.''
    We evaluated the current range of the distinct population segment 
of the North American wolverine to determine if there is any apparent 
geographic concentration of potential threats for the DPS. We examined 
potential threats due to human use and disturbance of habitat, 
trapping, and effects of climate change. We found no concentration of 
threats that suggests that the DPS of North American wolverine may be 
in danger of extinction in a portion of its range. We found no portions 
of the range where potential threats are significantly concentrated or 
substantially greater than in other portions of the range. Therefore, 
no portion of the range of the DPS of North American wolverine warrants 
further consideration of possible endangered or threatened species 
status under the Act.

References Cited

    A complete list of references cited in this rulemaking is available 
on the Internet at http://www.regulations.gov and upon request from the 
Montana Ecological Services Office (see FOR FURTHER INFORMATION 
CONTACT).

Authors

    The primary authors of this final rule are the staff members of the 
Montana Ecological Services Field Office and the Idaho Field Office 
(see FOR FURTHER INFORMATION CONTACT).

Authority

    The authority for this action is the Endangered Species Act of 
1979, as amended (16 U.S.C. 1531 et seq.).

    Dated: August 4, 2014.
Daniel M. Ashe,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 2014-18743 Filed 8-12-14; 4:15 pm]
BILLING CODE 4310-55-P