[Federal Register Volume 78, Number 23 (Monday, February 4, 2013)]
[Proposed Rules]
[Pages 7863-7890]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2013-01478]
[[Page 7863]]
Vol. 78
Monday,
No. 23
February 4, 2013
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 Rules
Federal Register / Vol. 78 , No. 23 / Monday, February 4, 2013 /
Proposed Rules
[[Page 7864]]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[FWS-R6-ES-2012-0107: 4500030113]
RIN 1018-AY26
Endangered and Threatened Wildlife and Plants; Threatened Status
for the Distinct Population Segment of the North American Wolverine
Occurring in the Contiguous United States
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Proposed rule.
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SUMMARY: We, the U.S. Fish and Wildlife Service, propose to list the
distinct population segment of the North American wolverine occurring
in the contiguous United States, as a threatened species under the
Endangered Species Act. If we finalize this rule as proposed, it would
extend the Act's protections to this species. The effect of this
regulation is to add the distinct population segment of the North
American wolverine occurring in the contiguous United States to the
List of Endangered and Threatened Wildlife in our regulations. We also
propose a special rule under section 4(d) of the Act to apply the
specific prohibitions of the Act necessary to protect the wolverine. We
find that critical habitat is not determinable at this time. The
Service seeks data and comments from the public on this proposed
listing rule, the proposed special rule under section 4(d) of the Act,
and our finding that the designation of critical habitat for the
species is not determinable at this time.
DATES: We will accept comments received or postmarked on or before May
6, 2013. Comments submitted electronically using the Federal
eRulemaking Portal (see ADDRESSES section, below) must be received by
11:59 p.m. Eastern Time on the closing date. We must receive requests
for public hearings, in writing, at the address shown in the ADDRESSES
section by March 21, 2013.
Public Informational Sessions and Public Hearing: We will hold 3
public informational sessions and public hearings on this proposed
rule. Public informational sessions will occur from 2:00 p.m. to 5:00
p.m. and public hearings will be held from 7:00 p.m. to 9:00 p.m. at
each location. Public informational sessions and public hearings will
occur in Boise, ID, on March 13, 2013, from 7:00 p.m. to 9:00 p.m.; in
Lakewood, CO, on March 19, 2013, from 7:00 p.m. to 9:00 p.m.; and in
Helena, MT, on March 27, 2013, from 7:00 p.m. to 9:00 p.m., all times
local (see ADDRESSES). Registration for those providing testimony in
the public hearings will begin at 6:00 p.m. at each location.
ADDRESSES: You may submit comments by one of the following methods:
(1) Electronically: Go to the Federal eRulemaking Portal: http://www.regulations.gov. In the Keyword box, enter Docket No. FWS-R6-ES-
2012-0107, which is the docket number for this rulemaking. Then, in the
Search panel on the left side of the screen, under the Document Type
heading, click on the Proposed Rules link to locate this document. You
may submit a comment by clicking on Comment Now!''
(2) By hard copy: Submit by U.S. mail or hand-delivery to: Public
Comments Processing, Attn: FWS-R6-ES-2012-0107; Division of Policy and
Directives Management; U.S. Fish and Wildlife Service; 4401 N. Fairfax
Drive, MS 2042-PDM; Arlington, VA 22203.
(3) At a public hearing: We are holding three public hearings on
this proposed rule (see ADDRESSES for location information). You may
provide your comments at any of the three hearings.
We request that you send comments only by the methods described
above. We will post all comments on http://www.regulations.gov. This
generally means that we will post any personal information you provide
us (see the Public Comments section below for more information).
Public Informational Sessions and Public Hearings: Public
informational sessions and public hearings will be held on March 13,
2013, at the Boise Centre on the Grove, 850 West Front Street, Boise,
ID 83702. The second is scheduled on March 19, 2013, at the Hampton
Inn, 137 Union Boulevard, Lakewood, CO 80228. The third is scheduled on
March 27, 2013, at the Red Lion Colonial Inn, 2301 Colonial Drive,
Helena, MT 59601. At all three locations the public informational
session will run from 2:00 p.m. to 5:00 p.m., followed by public
speaker registration at 6:00 p.m., and then the public hearing for oral
testimony from 7:00 p.m. to 9:00 p.m. People needing reasonable
accommodations in order to attend and participate in the public hearing
should contact Brent Esmoil, Montana Ecological Services Field Office,
as soon as possible (see FOR FURTHER INFORMATION CONTACT).
Any additional tools or supporting information that we may develop
for this rulemaking will be available at http://www.fws.gov/mountain-prairie/species/mammals/wolverine/, at http://www.regulations.gov at
Docket No. FWS-R6-ES-2012-0107, and at the Montana Field Office (see
FOR FURTHER INFORMATION CONTACT).
FOR FURTHER INFORMATION CONTACT: Brent Esmoil, Field Supervisor
(Acting), U.S. Fish and Wildlife Service, Montana Field Office, 585
Shepard Way, Helena, Montana 59601, by telephone (406) 449-5225.
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 a rule. Under the Endangered Species Act of
1973, as amended (16 U.S.C. 1531 et seq.) (Act or ESA), if a species is
determined to be an endangered or threatened species throughout all or
a significant portion of its range, we are required to promptly publish
a proposal in the Federal Register and make a determination on our
proposal within 1 year. Critical habitat shall be designated, to the
maximum extent prudent and determinable, for any species determined to
be an endangered or threatened species under the Act. Listing a species
as an endangered or threatened species and designations and revisions
of critical habitat can only be completed by issuing a rule.
This rule consists of:
A proposed rule to list the distinct population segment
(DPS) of the North American wolverine occurring in the contiguous
United States as a threatened species; and
A proposed special rule under section 4(d) of the Act that
outlines the prohibitions necessary and advisable for the conservation
of the wolverine.
A proposed rule under section 10(j) of the Act to establish an
experimental non-essential population of wolverine in Colorado is
published concurrently in this issue of the Federal Register. Also, a
draft Recovery Outline for the wolverine DPS is available on our Web
site at http://www.fws.gov/mountain-prairie/species/mammals/wolverine/
or on http://www.regulations.gov.
The basis for our action. Under the 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)
[[Page 7865]]
Other natural or manmade factors affecting its continued existence.
We have determined that habitat loss due to increasing temperatures
and reduced late spring snowpack due to climate change is likely to
have a significant negative population-level impact on wolverine
populations in the contiguous United States. In the future, wolverine
habitat is likely to be reduced to the point that the wolverine in the
contiguous United States is in danger of extinction.
We will seek peer review. We are seeking comments from
knowledgeable individuals with scientific expertise to review our
analysis of the best available science and application of that science
and to provide any additional scientific information to improve this
proposed rule. Because we will consider all comments and information
received during the comment period, our final determinations may differ
from this proposal.
Information Requested
We intend that any final action resulting from this proposed rule
will be based on the best scientific and commercial data available and
be as accurate and as effective as possible. Therefore, we request
comments or information from the public, other concerned governmental
agencies, Native American tribes, the scientific community, industry,
or any other interested parties concerning this proposed rule. We
particularly seek comments concerning:
(1) Biological, commercial trade, or other relevant data concerning
any threats (or lack thereof) to this species and regulations that may
be addressing those threats.
(2) Additional information concerning the historical and current
status, range, distribution, and population size of this species,
including the locations of any additional populations of this species.
(3) Any information on the biological or ecological requirements of
the species, and ongoing conservation measures for the species and its
habitat.
(4) Current or planned activities in the areas occupied by the
species and possible impacts of these activities on this species.
(5) The reasons why we should or should not designate habitat as
``critical habitat'' under section 4 of the Act (16 U.S.C. 1531 et
seq.) including whether and how the wolverine may benefit from such a
designation; whether there are threats to the species from human
activity, the degree to which it can be expected to increase due to a
critical habitat designation, and whether that increase in threat
outweighs the benefit of designation such that the designation of
critical habitat may not be prudent;
(6) Specific information on the amount and distribution of
wolverine habitat,
(7) Information on the projected and reasonably likely impacts of
climate change on the wolverine and its habitat;
(8) Suitability of the proposed 4(d) rule for the conservation,
recovery, and management of the DPS of the North American wolverine
occurring in the contiguous United States.
(9) Additional information concerning whether it is appropriate to
prohibit incidental take of wolverine in the course of legal trapping
activities directed at other species in the proposed 4(d) rule,
including any information about State management plans related to
trapping regulations and any measures within those plans that may avoid
or minimize the risk of wolverine mortality from incidental trapping
for other species.
(10) Additional provisions the Service may wish to consider to
conserve, recover, and manage the DPS of the North American wolverine
occurring in the contiguous United States.
We will consider all comments and information received during the
comment period on this proposed listing rule and special rule under
section 4(d) of the Act during our preparation of a final
determination. Accordingly, the final decision may differ from this
proposal.
Please note that submissions merely stating support for or
opposition to the action under consideration without providing
supporting information, although noted, will not be considered in
making a determination, as section 4(b)(1)(A) of the Act directs that
determinations as to whether any species is an endangered or threatened
species must be made ``solely on the basis of the best scientific and
commercial data available.''
You may submit your comments and materials concerning this proposed
rule by one of the methods listed in the ADDRESSES section. We request
that you send comments only by the methods described in the ADDRESSES
section.
If you submit information via http://www.regulations.gov, your
entire submission--including any personal identifying information--will
be posted on the Web site. If your submission is made via a hardcopy
that includes personal identifying information, you may request at the
top of your document that we withhold this information from public
review. However, we cannot guarantee that we will be able to do so. We
will post all hardcopy submissions on http://www.regulations.gov.
Please include sufficient information with your comments to allow us to
verify any scientific or commercial information you include.
Comments and materials we receive, as well as supporting
documentation we used in preparing this proposed rule, will be
available for public inspection on http://www.regulations.gov, or by
appointment, during normal business hours, at the U.S. Fish and
Wildlife Service, Montana Field Office (see FOR FURTHER INFORMATION
CONTACT).
Previous Federal Actions
On April 19, 1995, we published a finding (60 FR 19567) that a
previous petition, dated August 3, 1994, submitted by the Predator
Project (now named the Predator Conservation Alliance) and Biodiversity
Legal Foundation to list the wolverine in the contiguous United States
as an endangered or threatened species, did not provide substantial
information indicating that listing the wolverine in the contiguous
United States may be warranted.
On July 14, 2000, we received a petition dated July 11, 2000,
submitted by the Biodiversity Legal Foundation, Predator Conservation
Alliance, Defenders of Wildlife, Northwest Ecosystem Alliance, Friends
of the Clearwater, and Superior Wilderness Action Network, to list the
wolverine within the contiguous United States as an endangered or
threatened species and designate critical habitat for the species.
On October 21, 2003, we published a 90-day finding that the
petition failed to present substantial scientific and commercial
information indicating that listing may be warranted (68 FR 60112).
On September 29, 2006, as a result of a complaint filed June 8,
2005 by Defenders of Wildlife and others alleging we used the wrong
standards to assess the July 11, 2000, wolverine petition, the U.S.
District Court, Montana District, ruled that our 90-day petition
finding (68 FR 60112) was in error and ordered us to submit to the
Federal Register a 12-month finding for the wolverine by September 29,
2007. On April 6, 2007, the deadline for this 12-month finding was
extended to February 28, 2008.
On March 11, 2008, we published a 12-month finding of ``not
warranted'' for the wolverine in the contiguous United States (73 FR
12929). In that finding we determined that the wolverine in the
contiguous United States did not constitute a distinct population
segment or a significant portion of the range of a listable entity of
the wolverine in
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North America and so was not a listable entity under the Act.
On July 8, 2008 we received a Notice of Intent to Sue from
Earthjustice alleging violations of the Act in our March 11, 2008, 12-
month finding. On September 30, 2008, Earthjustice filed a complaint in
the U.S. District Court, District of Montana, seeking to set aside and
remand the 12-month finding back to the Service for reconsideration.
On March 6, 2009, the Service agreed to settle the case with
Earthjustice by voluntarily remanding the 12-month finding and issuing
a new 12-month finding by December 1, 2010. Following the settlement
agreement, the court dismissed the case on June 15, 2009, and ordered
the Service to comply with the settlement agreement.
On April 15, 2010, the Service published a Notice of Initiation of
a 12-month finding for wolverines in the contiguous United States (75
FR 19591). That finding was published on December 14, 2010, and
determined that the wolverine in the contiguous United States
constituted a Distinct Population Segment and that the DPS warranted
listing under the Act, but that listing was precluded by higher
priority listing actions (75 FR 78030).
On September 9, 2011, we reached an agreement with plaintiffs in
Endangered Species Act Section 4 Deadline Litig., Misc. Action No. 10-
377 (EGS), MDL Docket No. 2165 (D. DC) (known as the ``MDL case'') on a
schedule to publish proposed rules or to withdraw warranted findings
for the species on our list of candidate species. This agreement
stipulated that we would submit for publication in the Federal Register
a proposed listing rule for the wolverine, or withdraw the warranted
12-month finding, no later than the end of the 2013 Fiscal Year.
On April 13, 2012, several parties filed an action challenging the
Service's December 14, 2010 warranted but precluded finding for
wolverine. Cottonwood Envtl. Law Ctr., et al. v. Salazar, et al., 9:12-
cv-00057-DLC (D. Mont.) On September 20, 2012, the court granted the
Service's motion to stay that litigation based on the Service's
representation to the Court that it expected to submit this rule or
withdraw the warranted finding to the Federal Register by January 18,
2013.
Threatened Status for the Contiguous United States Wolverine DPS
Background
It is our intent to discuss below only those topics directly
relevant to the listing of the contiguous United States DPS of the
North American wolverine as a threatened species in this section of the
proposed rule.
Species Information
Taxonomy and Life History
The wolverine has a Holarctic (habitats found in the northern
continents) distribution including northern portions of Europe, Asia,
and North America. The currently accepted taxonomy classifies
wolverines worldwide as a single species, Gulo gulo, with two
subspecies. Old World wolverines are found in the Nordic countries of
Europe, Russia, and Siberia and are part of the subspecies Gulo gulo
gulo. New World wolverines occur in North America. The wolverines in
the contiguous United States are a part of the New World subspecies, G.
g. luscus: the North American wolverine (Kurten and Rausch 1959 p. 19;
Pasitschniak-Arts and Lariviere 1995, p. 1). The species is known by
several common names, including mountain devil, glutton, caracajou,
quickhatch, gulon, skunk bear, as well as wolverine.
The wolverine is the largest terrestrial member of the family
Mustelidae. Adult males weigh 12 to 18 kilograms (kg) (26 to 40 pounds
(lb)), and adult females weigh 8 to 12 kg (17 to 26 lb) (Banci 1994, p.
99). The wolverine resembles a small bear with a bushy tail. It has a
broad, rounded head; short, rounded ears; and small eyes. Each foot has
five toes with curved, semi-retractile claws used for digging and
climbing (Banci 1994, p. 99).
A large number of female wolverines (40 percent) are capable of
giving birth at 2 years old, become pregnant most years, and produce
average litter sizes of 1 to 2 kits. In one study of known-aged
females, none reproduced at age 2; 3 of 10 first reproduced at age 3;
and 2 did not reproduce until age 4. The average age at first
reproduction was 3.4 years (Persson et al. 2006, pp. 76-77). Another
study indicated that the average age at first reproduction is likely
more than 3 years (Inman et al. 2007c, p. 70). Pregnant females
commonly resorb or spontaneously abort litters prior to giving birth
(Magoun 1985, pp. 30-31; Copeland 1996, p. 43; Persson et al. 2006, p.
77; Inman et al. 2007c, p. 70). This may in turn preserve resources to
increase reproductive success in subsequent years (Persson 2005, p.
1456). By age 3, nearly all female wolverines become pregnant every
year, but energetic constraints due to low food availability result in
loss of pregnancy in about half of them each year. It is likely that,
in many places in the range of wolverines, it takes 2 years of foraging
for a female to store enough energy to successfully reproduce (Persson
2005, p. 1456). It is likely that, despite the high rate of initiation
of pregnancy, due to the spontaneous abortion of litters resulting from
resource limitation, actual rates of successful reproduction in
wolverines are among the lowest known for mammals (Persson 2005, p.
1456).
Supplemental feeding of females increases reproductive potential
(Persson 2005, p. 1456). Food-supplemented females were also more
successful at raising kits to the time of weaning, suggesting that
wolverine reproduction and ultimately population growth rates and
viability are food-limited. Female wolverines appear to use a complex
strategy of food accumulation and caching to attain enough resources to
successfully raise a litter (Inman et al. 2012b, pp. 640-641).
Breeding generally occurs from late spring to early fall (Magoun
and Valkenburg 1983, p. 175; Mead et al. 1991, pp. 808-811). Females
undergo delayed implantation until the following winter or spring, when
active gestation lasts from 30 to 40 days (Rausch and Pearson 1972, pp.
254-257). Litters are born from mid-February through March, containing
one to five kits, with an average in North America of between one and
two kits (Magoun 1985, pp. 28-31; Copeland 1996, p. 36; Krebs and Lewis
1999, p. 698; Copeland and Yates 2006, pp. 32-36; Inman et al. 2007c,
p. 68).
Female wolverines use natal (birthing) dens that are excavated in
snow. Persistent, stable snow greater than 1.5 meters (m) (5 feet (ft))
deep appears to be a requirement for natal denning, because it provides
security for offspring and buffers cold winter temperatures (Pulliainen
1968, p. 342; Copeland 1996, pp. 92-97; Magoun and Copeland 1998, pp.
1317-1318; Banci 1994, pp. 109-110; Inman et al. 2007c, pp. 71-72;
Copeland et al. 2010, pp. 240-242). Female wolverines go to great
lengths to find secure den sites, suggesting that predation is a
concern (Banci 1994, p. 107). Natal dens consist of tunnels that
contain well-used runways and bed sites and may naturally incorporate
shrubs, rocks, and downed logs as part of their structure (Magoun and
Copeland 1998, pp. 1315-1316; Inman et al. 2007c, pp. 71-72). In Idaho,
natal den sites occur above 2,500 m (8,200 ft) on rocky sites, such as
north-facing boulder talus or subalpine cirques (steep-walled
semicircular basin carved by a glacier) in forest openings (Magoun and
Copeland 1994, pp. 1315-1316). In Montana, natal dens occur above 2,400
m (7,874 ft) and are located on north aspects in avalanche debris,
[[Page 7867]]
typically in alpine habitats near timberline (Inman et al. 2007c, pp.
71-72). Offspring are born from mid-February through March and the dens
are typically used through late April or early May (Myrberget 1968, p.
115; Magoun and Copeland 1998, pp. 1314-1317; Inman et al. 2007b, pp.
55-59). Occupation of natal dens is variable, ranging from
approximately 9 to 65 days (Magoun and Copeland 1998, pp. 1316-1317).
Females may move kits to multiple secondary (maternal) dens as they
grow during the month of May (Pulliainen 1968, p. 343; Myrberget 1968,
p. 115), although use of maternal dens may be minimal (Inman et al.
2007c, p. 69). Timing of den abandonment is related to accumulation of
water in dens (due to snow melt), the maturation of offspring,
disturbance, and geographic location (Myrberget 1968, p. 115; Magoun
1985, p. 73). After using natal and maternal dens, wolverines may also
use rendezvous sites through early July. These sites are characterized
by natural (unexcavated) cavities formed by large boulders, downed logs
(avalanche debris), and snow (Inman et al. 2007c, pp. 55-56). Male
wolverines likely mate with several females, and although they are not
known to directly contribute to rearing young, they do tolerate
subadult wolverines in their territories (usually their own offspring)
until they reach maturity (Copeland 1996, p. 72).
Habitat, Space, and Food
In North America, wolverines occur within a wide variety of alpine,
boreal, and arctic habitats, including boreal forests, tundra, and
western mountains throughout Alaska and Canada. The southern portion of
the species' range extends into the contiguous United States, including
high-elevation alpine portions of Washington, Idaho, Montana, Wyoming,
California, and Colorado (Wilson 1982, p. 644; Hash 1987, p. 576; Banci
1994, p. 102, Pasitschniak-Arts and Lariviere 1995, p. 499; Aubry et
al. 2007, p. 2152; Moriarty et al. 2009, entire; Inman et al. 2009, pp.
22-25). Wolverines do not appear to specialize on specific vegetation
or geological habitat aspects, but instead select areas that are cold
and receive enough winter precipitation to reliably maintain deep
persistent snow late into the warm season (Copeland et al. 2010,
entire). The requirement of cold, snowy conditions means that, in the
southern portion of the species' range where ambient temperatures are
warmest, wolverine distribution is restricted to high elevations, while
at more northerly latitudes, wolverines are present at lower elevations
and even at sea level in the far north (Copeland et al. 2010, Figure
1).
In the contiguous United States, wolverines likely exist as a
metapopulation (Aubry et al. 2007, p. 2147, Figures 1, 3). A population
is a group of interbreeding individuals of the same species. A
metapopulation is a population composed of a network of semi-isolated
subpopulations, each occupying a suitable patch of habitat in a
landscape of otherwise unsuitable habitat (Pulliam and Dunning 1997,
pp. 212-214). Metapopulations require some level of regular or
intermittent migration and gene flow among subpopulations, in which
individual subpopulations support one-another by providing genetic and
demographic enrichment through mutual exchange of individuals (Meffe
and Carroll 1997, p. 678). Individual subpopulations may go extinct or
lose genetic viability, but are then ``rescued'' by immigration from
other subpopulations, thus ensuring the persistence of the
metapopulation as a whole. If metapopulation dynamics break down,
either due to changes within subpopulations or loss of connectivity,
then the entire metapopulation may be jeopardized due to subpopulations
becoming unable to persist in the face of inbreeding or demographic and
environmental stochasticity (Pulliam and Dunning 1997, pp. 221-222).
The wolverine metapopulation in the DPS consists of a network of small
subpopulations on mountain tops, some consisting of less than ten
individuals. Persistence of subpopulations under these conditions
requires movement between subpopulations across both suitable and
unsuitable wolverine habitat. Wolverines prefer to move across suitable
habitat (as defined by persistent spring snow cover) rather than to
cross unsuitable habitats during dispersal movements (Schwartz et al.
2009, p. 3230). Therefore, we would expect that changes resulting in
reduction of suitable habitat conditions would result in reduced
movement rates between habitat patches if distances between them became
greater. This could affect the metapopulation as a whole if movement
rates became too low to ensure subpopulation demographic or genetic
health.
Wolverines are opportunistic feeders and consume a variety of foods
depending on availability. They primarily scavenge carrion, but also
prey on small animals and birds, and eat fruits, berries, and insects
(Hornocker and Hash 1981, p. 1290; Hash 1987, p. 579; Banci 1994, pp.
111-113). Wolverines have an excellent sense of smell that enables them
to find food beneath deep snow (Hornocker and Hash 1981, p. 1297).
Wolverines require a lot of space; the availability and
distribution of food is likely the primary factor in determining female
wolverine movements and home range size (Hornocker and Hash 1981, p.
1298; Banci 1994, pp. 117-118). Male wolverine home range size and
location is likely tied to the presence of active female home ranges
and breeding opportunities (Copeland 1996, p. 74). Female wolverines
forage close to den sites in early summer, progressively ranging
further from dens as kits become more independent (May et al. 2010, p.
941). Wolverines travel long distances over rough terrain and deep
snow, and adult males generally cover greater distances 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). Home ranges of wolverines are
large, and vary greatly in size depending on availability and
distribution of food and gender and age of the animal. Home ranges of
adult wolverines also vary in size depending on geographic location.
Home ranges in Alaska were approximately 100 square kilometers (km\2\)
to over 900 km\2\ (38.5 square miles (mi\2\) to 348 mi\2\) (Banci 1994,
p. 117). Average home ranges of resident adult females in central Idaho
were 384 km\2\ (148 mi\2\), and average home ranges of resident adult
males were 1,522 km\2\ (588 mi\2\) (Copeland 1996, p. 50). Wolverines
in Glacier National Park had average adult male home ranges of 496
km\2\ (193 mi\2\) and adult female home ranges of 141 km\2\ (55 mi\2\)
(Copeland and Yates 2006, p. 25). Wolverines in the Greater Yellowstone
Ecosystem had average adult male home ranges of 797 km\2\ (311 mi\2\),
and average adult female home ranges of 329 km\2\ (128 mi\2\) (Inman et
al. 2007a, p. 4). These home range sizes are large relative to the body
size of wolverines, and may indicate that wolverines occupy a
relatively unproductive niche in which they must forage over large
areas to consume the amount of calories needed to meet their life-
history requirements (Inman et al. 2007a, p. 11).
Across their worldwide distribution, wolverines are dependent on
persistent spring snow cover for successful reproduction (Pulliainen
1968, pp. 338-341; Myrberget 1968, p. 115; Copeland 1996, pp. 93-94;
Magoun and Copeland 1998, pp. 1315-1319; Aubry et al. 2007, p. 2153;
Inman et al. 2012a, p.785; Copeland et al. 2010, entire). No records
exist of wolverines denning anywhere but in snow, despite the wide
[[Page 7868]]
availability of snow-free denning opportunities within the species'
geographic range. The snow tunnels and complex structure associated
with dens are likely required to protect young from interspecific and
intraspecific predation (Persson et al. 2003, pp. 25-26; Magoun and
Copeland 1998, p. 1318). A layer of deep snow may also add crucial
insulation from cold temperatures and wind prevalent in wolverine
habitat (Pulliainen 1968, p. 342; Bj[auml]rvall et al. 1978, p. 24-25;
Copeland 1996, p. 100; Magoun and Copeland 1998, p. 1318).
Female wolverines have been observed to abandon reproductive dens
when temperatures warm and snow conditions become wet (Magoun and
Copeland 1998, p. 1316); this response indicates that the condition of
the snow is also important to successful reproduction, and that the
onset of spring snowmelt forces female wolverines to move kits into
alternate denning sites with better snow conditions, if they are
available. These movements may be energetically costly and subject
females and kits to predation risk. The deep, persistent spring snow
layer in the Copeland et al. (2010) model captures all known wolverine
den sites in the DPS; however, on average, most denning occurs at
higher elevations within the area defined by the model. Female
wolverines establish reproductive dens at elevations higher than
average elevations used by nonreproductive wolverines (Copeland 1996,
p. 94; Magoun and Copeland 1998, pp. 1315-1316; Inman et al. 2007c, p.
71), suggesting that females find the conditions necessary for
successful denning in the upper portion of their home range where snow
is most persistent and occurs in the heaviest accumulations.
Wolverine year-round habitat use also takes place almost entirely
within the area defined by deep persistent spring snow (Copeland et al.
2010, pp. 242-243). Within the DPS, this area is generally centered on
the alpine tree line (the maximum elevation beyond which tree growth is
precluded and only low-growing vegetation is found). In the contiguous
United States, wolverine year-round habitat is found at high elevations
centered near the tree line in conifer forests (below tree line) and
rocky alpine habitat (above tree-line) and in cirque basins and
avalanche chutes that have food sources such as marmots, voles, and
carrion (Hornocker and Hash 1981, p. 1296; Copeland 1996, p. 124;
Magoun and Copeland 1998, p. 1318; Copeland et al. 2007, p. 2211; Inman
et al. 2007a, p. 11). In the southern portion of wolverine range in
North America which includes the DPS, wolverines are constrained by
their need for cold conditions and persistent spring snow to using only
the coldest available landscapes (Copeland et al. 2010, Figure 6).
Mean seasonal elevations used by wolverines in the northern Rocky
Mountains and North Cascades vary between 1,400 and 2,600 m (4,592 and
8,528 ft) depending on location, but are always relatively high on
mountain slopes (Hornocker and Hash 1981, p. 1291; Copeland et al.
2007, p. 2207, Aubry et al. 2007, p. 2153; Inman et al. 2012, p. 782).
Elevation ranges used by historical wolverine populations in the Sierra
Nevada and southern Rocky Mountains are unknown, but presumably
wolverines used higher elevations, on average, than more northerly
populations to compensate for the higher temperatures found at lower
latitudes. In the contiguous United States, valley bottom habitat
appears to be used only for dispersal movements and not for foraging or
reproduction (Inman et al. 2009, pp. 22-28). Wolverine reproductive
dens have been located in alpine, subalpine, taiga, or tundra habitat
(Myrberget 1968, p. 115; Pulliainen 1968, pp. 338-341; Bj[auml]rvall
1982, p. 318; Lee and Niptanatiak 1996, p. 349; Landa et al. 1998, pp.
451-452; Magoun and Copeland 1998, pp. 1317-1318). Wolverines rarely,
or never, den in lower elevation forested habitats, although they may
occupy these habitats occasionally (Magoun and Copeland 1998, p. 1317).
Wolverine Densities
Wolverines naturally occur in low densities with a reported range
from one animal per 65 km\2\ (25 mi\2\), to one animal per 337 km\2\
(130 mi\2\) (Hornocker and Hash 1981, pp. 1292-1295; Hash 1987, p. 578;
Copeland 1996, pp. 31-32; Copeland and Yates 2006, p. 27; Inman et al.
2007a, p. 10; Squires et al. 2007, p. 2218). No systematic population
census exists over the entire current range of wolverines in the
contiguous United States, so the current population level and trends
are not known with certainty. However, based on our current knowledge
of occupied wolverine habitat and wolverine densities in this habitat,
it is reasonable to estimate that the wolverine population in the
contiguous United States numbers approximately 250 to 300 individuals
(Inman 2010b, pers. comm.). The bulk of the current population occurs
in the northern Rocky Mountains, with a few individuals in the North
Cascades and one known individual each in the Sierra Nevada and
southern Rocky Mountains. Within the area known to currently have
wolverine populations, relatively few wolverines can coexist due to
their naturally low population densities, even if all areas were
occupied at or near carrying capacity. Given the natural limitations on
wolverine population density, it is likely that historical wolverine
population numbers were also low (Inman et al. 2007a, Table 6). Because
of these natural limitations, it is possible that densities and
population levels in the northern Rocky Mountains and North Cascades
where populations currently exist may not be substantially lower than
population densities were in these areas prior to European settlement.
However, historically, the contiguous United States population would
likely have been larger than it is today due to the larger area
occupied by populations when the southern Rocky Mountains, Bighorn
Mountains, Sierra Nevada, and possibly also the Oregon Cascades and
mountains of Utah, were occupied at full capacity.
Wolverine Status in Canada and Alaska
The bulk of the range of North American wolverines is found in
Canada and Alaska, where wolverines inhabit alpine tundra, boreal
forest, and arctic habitats (Slough 2007, p. 78). Wolverines in Canada
have been divided into two populations for management by the Canadian
Government: An eastern population in Labrador and Quebec, and a western
population that extends from Ontario to the Pacific coast, and north to
the Arctic Ocean. The eastern population is currently listed as
endangered under the Species At Risk Act in Canada, and the western
population is designated as a species of special concern (COSEWIC 2003,
p. 8).
The current status of wolverines in eastern Canada is uncertain.
Wolverines have not been confirmed to occur in Quebec since 1978
(Fortin et al. 2005, p. 4). Historical evidence of wolverine presence
in eastern Canada is also suspect because no evidence exists to show
that wolverine pelts attributed to Quebec or Labrador actually came
from that region; animals were possibly trapped elsewhere and the pelts
shipped through the eastern provinces (COSEWIC 2003, p. 20). Wolverines
in eastern Canada may currently exist in an extremely low-density
population, or may be extirpated. Wolverines in eastern Canada, both
historically and currently, could represent migrants from western
populations that never became resident animals (COSEWIC 2003, pp. 20-
21). The Federal Government of Canada has completed a recovery plan
[[Page 7869]]
for the eastern population with the goal of establishing a self-
sustaining population through reintroduction and protection (Fortin et
al. 2005, p. 16).
Wolverines in western Canada and Alaska inhabit a variety of
habitats from sea level to high elevations (Slough 2007, pp. 77-78).
They occur in Alaska, Ontario, Manitoba, Saskatchewan, Alberta, British
Columbia, Yukon, Northwest Territories, and Nunavut (Slough 2007, pp.
77-78). Since European colonization, a generally recognized range
contraction has taken place in boreal Ontario and the aspen parklands
of Manitoba, Saskatchewan, and Alberta (COSEWIC 2003, pp. 20-21; Slough
2007, p. 77). This range contraction occurred concurrently with a
reduction in wolverine records for the Great Lakes region in the
contiguous United States (Aubry et al. 2007, pp. 2155-2156). Causes of
these changes are uncertain, but may be related to increased harvest,
habitat modification, or climate change (COSEWIC 2003, pp. 20-21; Aubry
et al. 2007, pp. 2155-2156; Slough 2007, pp. 77-78). Analysis supports
climate change as a factor contributing to population declines in
southern Ontario, because snow conditions necessary to support
wolverines do not currently exist in the Great Lakes region of the
contiguous United States, and are marginal in southern Ontario (Aubry
et al. 2007, p. 2154). It is not known if these snow conditions existed
historically in the Great Lakes of the contiguous United States;
however, the small number of wolverine records from this area suggests
that they did not. It is possible that suitable snow conditions did
reach further south in eastern Canada in 1850 than they do today,
making wolverine dispersal attempts from Canada to the Great Lakes
region of the contiguous United States more likely than they are now.
Wolverines occurred historically on Vancouver Island and have been
given status as a separate subspecies by some (Hall 1981, p. 109). The
Vancouver Island population is now regarded as possibly extirpated; no
sightings have occurred since 1992 (COSEWIC 2003, p. 18).
Wolverines in western Canada and Alaska appear to persist
everywhere that habitat and climate conditions are suitable (COSEWIC
2003, pp. 13-21; Aubry et al. 2007, pp. 2152-2155; Slough 2007, p. 79;
Copeland et al. 2010, Figure 2). Throughout this area, wolverines are
managed by regulated harvest at the Provincial and State level.
Population estimates for Canada and Alaska are rough because no
wolverine surveys have taken place at the State or Provincial scale.
However, the population in western Canada is estimated to include
approximately 15,089 to 18,967 individuals (COSEWIC 2003, p. 22). The
number of wolverines in Alaska is unknown, but they appear to exist at
naturally low densities in suitable habitats throughout the state
(Alaska Department of Fish and Game 2004, pp. 1-359). We have no
information to indicate that wolverine populations have been reduced in
numbers or geographic range in Alaska.
The Complexity of Geographic Range Delineation
Information on the nature of historical and current locations of
wolverine is lacking for several reasons. Wolverines tend to live in
remote and inhospitable places away from human settlements, where they
are seldom encountered, documented, or studied. Wolverines naturally
occur at low population densities and are rarely and unpredictably
encountered where they do occur. Wolverines often move long distances
in short periods of time; for example, when dispersing from natal
ranges, wolverines may transit through habitats that are unsuitable for
long-term survival (Aubry et al. 2007, p. 2147; Moriarty et al. 2009,
entire; Inman et al. 2009, pp. 22-28; Brian 2010, p. 3). Such movements
make it difficult to distinguish with certainty between occurrence
records that represent established populations in suitable habitats and
records that represent short-term occupancy or exploratory movements
without the potential for establishment of home ranges, reproduction,
or populations. These natural attributes of wolverines make it
difficult to precisely determine their present range, or trends in
range expansion or contraction, that may have occurred in the past.
Therefore, we are cautious and use multiple lines of evidence when
trying to determine where past wolverine populations occurred.
Throughout the remainder of this proposed rule, we focus on the use
of verifiable and documented wolverine occurrence records to define
historical and present range as we have determined that these records
constitute the best scientific information available on the past and
present distribution of wolverines (see Aubry et al. 2007, p. 2148;
McKelvey et al. 2008, entire). Verifiable records are records supported
by physical evidence such as museum specimens, harvested pelts, DNA
samples, and diagnostic photographs. Documented records are those based
on accounts of wolverines being killed or captured. Use of only
verifiable and documented records avoids mistakes of misidentification
often made in eyewitness accounts of visual encounters of unrestrained
animals in the wild. Visual-encounter records often represent the
majority of occurrence records for elusive forest carnivores, and they
are subject to inherently high rates of misidentification of the
species involved, including wolverines (McKelvey et al. 2008, pp. 551-
552). These misidentifications can result in wildly inaccurate
conclusions about species occurrence (McKelvey et al. 2008, pp. 550-
553).
Aubry et al. (2007, entire) used only verifiable and documented
records to investigate wolverine distribution through time. This paper
is the only available comprehensive treatment of these distribution
patterns that attempts to distinguish between records that represent
resident animals versus animals that have dispersed outside of suitable
habitat. For these reasons, we find that Aubry et al. (2007, entire)
represents the best available summary of wolverine occurrence records
in the contiguous United States at this time. Since the publication of
Aubry et al. (2007, entire), verified records of wolverines have also
been documented in Colorado and California, which we will describe in
greater detail below.
Aubry et al. (2007, entire) used verifiable and documented records
from museum collections, literature sources, and State and Federal
institutions to trace changes in geographic distribution of wolverines
in the historical record. They then used an overlay of suitable
wolverine habitats to determine which records represent wolverines in
habitats that may support residency, and, by extension, populations,
and which records likely represent wolverines outside the range of
suitable habitats, so called ``extralimital'' records. Aubry et al.'s
(2007, entire) focus on verifiable and documented records corrected
past overly broad approaches to wolverine range mapping (Nowak 1973, p.
22; Hall 1981, p. 1009; Wilson 1982, p. 644; Hash 1987, p. 576), which
used a more inclusive but potentially misleading approach when dealing
with occurrence records. Many of the extralimital records used in these
publications represented individuals that dispersed from natal ranges
but ended up in habitats that could not support wolverines. Use of
these data to determine the historical geographic range of wolverines
results in gross overestimation of the area that can actually be used
successfully by wolverines for the establishment of populations.
Subsequent to publication of Aubry et al. (2007, entire), two
publications (Copeland et al. 2010,
[[Page 7870]]
entire; Brock et al. 2007, entire) further refined our understanding of
wolverine habitat needs and corroborated the approach of Aubry et al.
(2007, entire). Thus, despite the paucity of verifiable records, we now
have strong information on the areas that are currently suitable to be
occupied by wolverine based on habitat and climate conditions.
We agree with Aubry et al. (2007, p. 2149) that the most
appropriate method to determine the current and historical range of
wolverines is to use a combination of occurrence records and habitat
suitability, along with other information, such as documented
successful reproduction events, indicating where reproductive and
potentially self-sustaining populations may occur. We also generally
agree with their conclusions about the historical and current range of
the species. We find that the species' range is the area that may
support viable populations, and does not include extralimital
occurrences outside of habitat that is likely to support wolverine
life-history needs. Areas that can support wolverine populations may be
referred to as potential ``source'' populations because they provide
surplus individuals through reproduction beyond what is needed for
replacement. Areas that have some of the habitat attributes of
wolverine habitat but do not have enough habitat to support viable
populations may be referred to as population ``sinks'' because
wolverines may disperse to these areas and remain for some time, but
will either die there without reproducing, leave the area in search of
better habitat conditions, or may actually reproduce, but at a rate
lower than that needed for replacement of individuals lost to mortality
or emigration, leading to eventual population extinction.
For a widely dispersing species like the wolverine, we expect many
locality records to represent dispersal attempts into sink habitats or
nonhabitat. The value to the population (and thus the DPS) of
dispersers in these areas is unclear; it is likely that most dispersers
into sink habitats or nonhabitat will be lost to the population unless
they are able to move back into source habitats. Therefore, it is our
conclusion that population sink areas and areas of non-wolverine
habitat, here defined as places where wolverines may be found but where
habitat is not suitable for long-term occupancy and reproduction, do
not represent part of the species historical range and have little
conservation value for the DPS, other than possibly serving as
temporary stop-overs for attempted dispersers as they search for
suitable habitats. Compared with broader approaches to defining
historical geographic range, this focused approach (1) results in
reducing the bias of extralimital dispersers and (2) concentrates
conservation attention on areas capable of maintaining populations.
Aubry et al. (2007, pp. 2147-2148) divided records into
``historical'' (recorded prior to 1961), ``recent'' (recorded between
1961 and 1994), and ``current'' (recorded after 1994). Historical
records occurred before systematic surveys. Historical records
encompass the time during which wolverine numbers and distribution were
hypothesized to be at their highest (prior to European settlement) and
also at their lowest (early 20th century) (Wright and Thompson 1935;
Grinnell et al. 1937; Allen 1942; Newby and Wright 1955, all as cited
in Aubry et al. 2007, p. 2148). The recent time interval covers a
hypothesized population expansion and rebound from the early 20th
century low. Current records offer the most recent evidence available
for wolverine occurrences and potential populations. All occurrence
records must be individually analyzed in light of their context in
terms of habitat conditions conducive to wolverine population
establishment and whether or not they occur clustered with other
records, which might indicate that populations have historically
occurred in the area. The authors of Aubry et al. (2007) did such an
analysis as they compiled their records.
Wolverine Distribution
We assessed the historical, recent, and current distribution data
for each of the regions below to determine the likelihood of the
presence of historical populations (rather than extralimital
dispersers). Of 729 mappable records (those records with precise
location information) compiled by Aubry et al. (2007, p. 2150), 188
were from the historical time interval (see Table 1). The discussion
below draws heavily from both Aubry et al. (2007, entire) and Copeland
et al. (2010, entire).
Table 1--Wolverine Records From Three Time Periods From Aubry et al. 2007
[Numbers represent total documented and verifiable records with the subset of those records that were verifiable in parentheses]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Historical (<1964) Recent (1961-1994) Current (>1994)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Northeast..................................................... 13 (1) 0 0
Upper Midwest................................................. 4 (2) 0 0
Great Lakes................................................... 36 (4) 1 0
Central Great Plains.......................................... * 71 (2) 1 0
Rocky Mountains............................................... 147 (45) 332 (283) 215 (210)
Pacific Coast................................................. 89 (14) 23 (15) 7
-----------------------------------------------------------------------------------------
Totals.................................................... 362 (68) 357 (298) 222 (210)
--------------------------------------------------------------------------------------------------------------------------------------------------------
* 35 records from a single source (the journals of Alexander Henry).
Northeast and Upper Midwest--The low number of records and
scattered nature of their distribution combined with a lack of suitable
habitat indicate that wolverines were likely only occasional transients
to the area and not present as a reproducing population after 1800.
Great Lakes--The lack of large numbers of verifiable records in
this area of relatively high human population density and the lack of
suitable habitat suggests that wolverines did not exist in this area as
a viable population after 1900. Widely scattered records generally
before 1900, along with occasional subsequent records suggest that if a
reproducing population existed in the Great Lakes, it predated 1900,
and that any post-1900 records represent dispersal from a receding
Canadian population. Wolverine distribution in Ontario, Canada, appears
to have receded north from the Great Lakes region since the 1800s, and
currently wolverines occupy only the northern portion of the province,
a distance of over 644 km (400 mi) from the United States border
(COSEWIC 2003, p. 9). The distribution pattern of
[[Page 7871]]
record illustrated in Aubry et al. (2007, p. 2152) is consistent with
what would be expected if those records were of dispersing individuals
from a Canadian population that receded progressively further north
into Canada after 1800, possibly due to natural climate changes
(COSEWIC 2003, p. 28).
Central Great Plains--The lack of precise locality records and
suitable habitat from the Great Plains States leads us to conclude that
reproducing populations of wolverines did not historically inhabit this
area. Of thirty-six records from North Dakota, 35 are from the journals
of a single fur trader (see Table 1), and it is not clear that the
records represent actual collection localities or are localities where
trades or shipments occurred (Aubry 2007, pers. comm.). Given the
habitat relationships of wolverines (e.g., Copeland et al. 2010, Figure
1), it is unlikely that these records represent established wolverines
or that this area served as wolverine habitat.
Rocky Mountains--Five Rocky Mountains States (Idaho, Montana,
Wyoming, Colorado, and Utah) contained numerous wolverine records.
Records with precise locality information appear to coalesce around
several areas that may have been population centers, such as central
Colorado, the greater Yellowstone region, and northern Idaho-
northwestern Montana. The large number of verifiable and documented
records for this region, along with the suggestion of population
centers or strongholds, suggests that wolverines existed in reproducing
populations throughout much of the Rocky Mountains during the
historical time interval. The lack of records for Colorado and Utah
after 1921 suggests that the southern Rocky Mountains population of
wolverines was extirpated in the early 1900s, concurrent with
widespread systematic predator control by government agencies and
livestock interests. The northern Rocky Mountains population (north of
Wyoming) was reduced to historical lows or possibly even extirpated
during the early 1900s, and then increased dramatically in the second
half of the 1900s (see Table 1) as predator control efforts subsided
and trapping regulations became more restrictive (Aubry et al. 2007, p.
2151). This increase likely indicates a population rebound from
historical lows in this period.
Wolverine records from 1995 to 2005 indicate that wolverine
populations currently exist in the northern Rocky Mountains (see Table
1). Legal trapping in Montana in the recent past removed an average of
10.5 individuals from this population each year (Montana Department of
Fish, Wildlife, and Parks 2007, p. 2), but harvest mortality has been
reduced due to regulatory changes in 2008 (Montana Department of Fish,
Wildlife and Parks 2008, p. 8). Populations in British Columbia and
Alberta, Canada, are extant (COSEWIC 2003, pp. 18-19), and may have
been a source of surplus wolverines to the contiguous United States
population during population lows. Recently, a male wolverine moved on
its own from the southern Greater Yellowstone Area of Wyoming into the
southern Rocky Mountains of Colorado, where it still persisted as of
November 2012 (Inman et al. 2009, pp. 22-26; Odell 2012, pers. comm.).
This attempted dispersal event is the first verified wolverine
occurrence in Colorado since 1919 and may represent a continuation of
the wolverine expansion in the Rocky Mountains detailed above. It is
possible that other wolverines have traveled to the southern Rocky
Mountains and have remained undetected. There is no evidence that
Colorado currently hosts a wolverine population or that female
wolverines have made, or are likely to make, similar movements. Female
dispersal movements tend to be much shorter than males, usually
occupying home ranges adjacent to their natal range, and dispersal is
documented only for lesser distances than males routinely travel
(Hornocker and Hash 1981, p. 1290; Copeland 1996, p. 91; Kyle and
Strobeck 2001, p. 338; Tomasik and Cook 2005, p. 390; Cegelski et al.
2006, p. 206, Inman et al. 2011, p. 7). The largest documented female
movement occurred in 2010 in the North Cascades of Washington (Aubry et
al. 2011, pp. 21-22). In that instance, a radio-collared female
wolverine moved an air-line distance of approximately 233 km (145 mi)
over a 44-day period. During this movement, her course generally stayed
within suitable wolverine habitat (as defined by Copeland et al. (2010,
p. 242)) and was never more than about 19 km (12 mi) from suitable
wolverine habitat.
Pacific Coast--Historical records show that wolverines occurred in
two population centers in the North Cascades Range and the Sierra
Nevada. However, records do not show occurrences between these centers
from southern Oregon to northern California, indicating that the
historical distribution of wolverines in this area is best represented
by two disjunct populations rather than a continuous peninsular
extension from Canada. This conclusion is supported by genetic data
indicating that the Sierra Nevada and Cascades wolverines were
separated for at least 2,000 years prior to extirpation of the Sierra
Nevada population (Schwartz et al. 2007, p. 2174).
Only one Sierra Nevada record exists after 1930, indicating that
this population was likely extirpated in the first half of the 1900s,
concurrent with widespread systematic predator control programs. In
2008, a male wolverine was discovered in the Sierra Nevada Range of
California, the first verified record from California since 1922
(Moriarty et al. 2009, entire). Genetic testing revealed that this
wolverine was not a descendant of the endemic Sierra Nevada wolverine
population, but was likely derived from wolverines in the Rocky
Mountains (Moriarty et al. 2009, p. 159). This attempted dispersal
event may represent a continuation of the wolverine expansion in the
contiguous United States as detailed above. Other wolverines may have
travelled to the Sierra Nevada and remain undetected. There is no
evidence that California currently hosts a wolverine population or that
female wolverines have made, or are likely to make, similar dispersal
movements.
Wolverines were likely extirpated from the North Cascades in the
early 20th century and then recently recolonized from Canada.
Currently, a small population persists in this area (Aubrey et al.
2011, entire). In 2012, reproduction was documented for the first time
in the North Cascades (Aubry et al. 2012, p. 2). Wolverines have also
been documented in the southern portion of the North Cascades, near
Mount Adams, since 2009 (Akins 2010, p. 4). The North Cascades
population may be connected with, and is possibly dependent on, the
larger Canadian population for future expansion and long-term
persistence.
Summary of Wolverine Distribution
Historical wolverine records were found across the northern tier of
the contiguous United States, with convincing evidence of wolverine
populations in the northern and southern Rocky Mountains, Sierra Nevada
Mountains, and North Cascades Mountains (Aubry et al. 2007, p. 2152).
Currently, wolverines appear to be distributed as functioning
populations in two regions in the contiguous United States: the North
Cascades in Washington, and the northern Rocky Mountains in Idaho,
Montana, and Wyoming (this area also includes the Wallowa Range in
Oregon). Wolverines were likely extirpated, or nearly so, from the
entire contiguous United States in the first half of the 20th century
[[Page 7872]]
(Aubry et al. 2007, Table 1). Although the reasons for this extirpation
are not known with certainty, unregulated trapping and widespread
indiscriminant predator control likely contributed to population
declines. The available evidence suggests that, in the second half of
the 20th century and continuing into the present time, wolverine
populations have expanded in the North Cascades and the northern Rocky
Mountains from sources in Canada, but that populations have not been
reestablished in the Sierra Nevada Range or the southern Rocky
Mountains, despite the known movement of single individual males to
each of these areas. We conclude that the current range of the species
in the contiguous United States includes the North Cascades Mountains,
the northern Rocky Mountains, the southern Rocky Mountains, and the
Sierra Nevada Mountains, but that reestablishment of populations in the
southern Rocky Mountains and Sierra Nevada Mountains has not yet
occurred.
We also conclude that wolverines either did not exist as
established populations, or were extirpated prior to settlement and the
compilation of historical records, in the Great Lakes region, possibly
due to climate changes that occurred through the 1800s and 1900s. The
Great Lakes region lacks suitable wolverine habitat, and suitable
habitat does not appear to exist in adjacent Canada (Copeland et al.
2010, Figure 1). The widely scattered records from this region are
consistent with dispersing individuals from a Canadian population that
receded north early in the 1800s. We cannot rule out the possibility
that wolverines existed as established populations prior to the onset
of trapping in this area, but we have no evidence of this.
No evidence in the historical records indicates that wolverines
were ever present as established populations in the Great Plains,
Midwest, or Northeast.
Habitat Relationships and Wolverine Distribution
Deep, persistent, and reliable spring snow cover (April 15 to May
14) is the best overall predictor of wolverine occurrence in the
contiguous United States (Aubry et al. 2007, pp. 2152-2156; Copeland et
al. 2010, entire). Deep, persistent snow correlates well with wolverine
year-round habitat use across wolverine distribution in North America
and Eurasia at both regional and local scales (Copeland et al. 2010,
entire; Inman et al. 2012a, p. 785). It is uncertain why spring snow
cover so accurately predicts wolverine habitat use; however, it is
likely related to wolverines' need for deep snow during the denning
period. In addition, wolverines appear to take advantage of a cold,
low-productivity niche by using food caching in cold habitats to
survive food-scarce winters that other carnivores cannot (Inman et al.
2012b, pp. 640-642). Wolverines' physiological requirement for year-
round cold temperatures may also play a role in habitat use (Copeland
et al. 2010, pp. 242-243). Snow cover during the denning period is
essential for successful wolverine reproduction range-wide (Hatler
1989, p. iv; Magoun and Copeland 1998, p. 1317; Inman et al. 2007c, pp.
71-72; Persson 2007; Copeland et al. 2010, p. 244). Wolverine dens tend
to be in areas of high structural diversity such as logs and boulders
with deep snow (Magoun and Copeland 1998, p. 1317; Inman et al. 2007c,
pp. 71-72; Persson 2007, entire). Reproductive females dig deep snow
tunnels to reach the protective structure provided by logs and
boulders. This behavior presumably protects the vulnerable kits from
predation by large carnivores, including other wolverines (Pulliainen
1968, p. 342; Zyryanov 1989, pp. 3-12), but may also have physiological
benefits for kits by buffering them from extreme cold, wind, and
desiccation (Pullianen 1968, p. 342, Bj[auml]rvall et al. 1978, p. 23).
Wolverines live in low-temperature conditions and appear to select
habitats in part to avoid high summer temperatures (Copeland et al.
2010, p. 242). Wolverine distribution is likely affected by climatic
conditions at two different scales. Wolverines require deep persistent
snow for denning, and this likely determines where wolverine
populations can be found at the grossest range-wide scale (Copeland et
al. 2010, p. 244). At smaller scales, wolverines likely select habitats
to avoid high summer temperatures. These cool habitats also tend to
retain snow late into spring, leading to wolverines' year-round
association with areas of persistent spring snow (Copeland et al. 2010,
p. 244).
All of the areas in the contiguous United States for which good
evidence of persistent wolverine populations (either present or
historical) exists (i.e., North Cascades, Sierra Nevada, northern and
southern Rocky Mountains) contain large and well-distributed areas of
deep snow cover that persists through the wolverine denning period
(Inman et al. 2011, Fig. 3; Aubry et al. 2007, p. 2154; Copeland et al.
2010, Figure 1). The Great Plains, Great Lakes, Midwest, and Northeast
lack the spring snow conditions and low summer temperatures thought to
be required by wolverines for successful reproduction and year-round
occupancy (Aubry et al. 2007, p. 2154; Copeland et al. 2010, Figure 1).
The lack of persistent spring snow conditions in the Great Plains,
Great Lakes, Midwest, and Northeast supports the exclusion of these
areas from the current range of wolverines. Whether wolverines once
existed as established populations in any of these regions is
uncertain, but the current climate appears to preclude their presence
as reproducing populations, and the sparse historical record of
wolverine presence in this area makes historical occupation of these
areas by wolverine populations doubtful. It is our conclusion that the
ecosystem that supports wolverines does not exist in these areas
currently, and may not have existed at the time of European settlement
of these areas.
Large areas of habitat with characteristics suitable for wolverines
still occur in the southern Rocky Mountains and Sierra Nevada, despite
the extirpation of wolverines from those areas (Aubry et al. 2007, p.
2154, Inman et al. 2011, Fig. 4; Copeland et al. 2010, Figure 1).
Wolverine extirpations in these areas were coincident with unregulated
trapping and systematic predator eradication efforts in the early
1900s, which have been discontinued for many years. Each of these areas
has received at least one and possibly more migrants from adjacent
populations in the northern Rocky Mountains; however, there is no
evidence that females have migrated to these areas or that populations
of wolverines currently exist there (Aubry et al. 2007, Table 1;
Moriarty et al. 2009, entire; Inman et al. 2009, entire).
We conclude that areas of wolverine historical occurrence can be
placed in one of three categories: (1) Areas where wolverines are
extant as reproducing and potentially self-sustaining populations
(North Cascades, northern Rocky Mountains); (2) areas where wolverines
historically existed as reproducing and potentially self-sustaining
populations prior to human-induced extirpation, and where
reestablishment of those populations is possible given current habitat
conditions and management (the Sierra Nevada Mountains in California
and southern Rocky Mountains in Colorado, New Mexico, Wyoming, Uinta
Mountains and surrounding ranges in Utah, Bighorn Mountains in Wyoming,
and possibly the Oregon Cascades Mountains); and (3) areas where
historical presence of wolverines in reproducing and potentially self-
sustaining populations is doubtful, and
[[Page 7873]]
where the current habitat conditions preclude the establishment of
populations (Great Plains, Midwest, Great Lakes, and Northeast). We,
therefore, consider the current range of wolverines to include suitable
habitat in the North Cascades of Washington, the northern Rocky
Mountains of Idaho, Wyoming, Montana, and eastern Oregon, the southern
Rocky Mountains of Colorado and Wyoming, and the Sierra Nevada of
California. We here include the Sierra Nevada and southern Rocky
Mountains in the current range of wolverines despite the probability
that functional populations do not exist in these areas. They are
included due to the known existence of one individual in each area and
the possibility that more, as yet undetected, individuals inhabit these
areas.
Distinct Population Segment
Pursuant to the Act, we must consider for listing any species,
subspecies, or, for vertebrates, any Distinct Population Segment (DPS)
of these taxa, if there is sufficient information to indicate that such
action may be warranted. To interpret and implement the DPS provision
of the Act and Congressional guidance, the Service and the National
Marine Fisheries Service published, on February 7, 1996, an interagency
Policy Regarding the Recognition of Distinct Vertebrate Population
Segments under the Act (61 FR 4722). This policy addresses the
recognition of DPSs for potential listing actions. The policy allows
for more refined application of the Act that better reflects the
biological needs of the taxon being considered, and avoids the
inclusion of entities that do not require its protective measures.
Under our DPS policy, three elements are considered in a decision
regarding the status of a possible DPS as endangered or threatened
under the Act. These are applied similarly for additions to the list of
endangered and threatened species, reclassification, and removal from
the list. They are: (1) Discreteness of the population segment in
relation to the remainder of the taxon; (2) the biological or
ecological significance of the population segment to the taxon to which
it belongs; and (3) the population segment's conservation status in
relation to the Act's standards for listing (i.e., whether the
population segment is, when treated as if it were a species or
subspecies, an endangered or threatened species). Discreteness refers
to the degree of isolation of a population from other members of the
species, and we evaluate this factor based on specific criteria. If a
population segment is considered discrete, we must consider whether the
discrete segment is ``significant'' to the taxon to which it belongs by
using the best available scientific and commercial information. If we
determine that a population segment is both discrete and significant,
we then evaluate it for endangered or threatened species status based
on the Act's standards. The DPS evaluation in this proposed rule
concerns the segment of the wolverine species occurring within the
contiguous 48 States, including the northern and southern Rocky
Mountains, Sierra Nevada Range, and North Cascades Range.
Distinct Population Segment Analysis for Wolverine in the Contiguous
United States
Analysis of Discreteness
Under our DPS Policy, a population segment of a vertebrate species
may be considered discrete if it satisfies either one of the following
conditions: (1) It is markedly separated from other populations of the
same taxon as a consequence of physical, physiological, ecological, or
behavioral factors (quantitative measures of genetic or morphological
discontinuity may provide evidence of this separation); or (2) it is
delimited by international governmental boundaries within which
differences in control of exploitation, management of habitat,
conservation status, or regulatory mechanisms exist that are
significant in light of section 4(a)(1)(D) of the Act (inadequacy of
existing regulatory mechanisms). The wolverine within the contiguous
United States meets the second DPS discreteness condition because of
differences in conservation status as delimited by the Canadian-United
States international governmental boundary.
In our 12-month finding for the North American wolverine DPS (75 FR
78030) we conducted a complete analysis of the discreteness of the
wolverine DPS that we incorporate here by reference. In that analysis
we concluded that the international boundary between Canada and the
United States currently leads to division of the control of
exploitation and conservation status of the wolverine. This division is
significant because it allows for potential extirpation of the species
within the contiguous United States through loss of small populations
and lack of demographic and genetic connectivity of the two
populations. This difference in conservation status is likely to become
more significant in light of threats discussed in the five factors
analyzed below. Therefore, we find that the difference in the
conservation statuses in Canada and the United States result in
vulnerability to the significant threat (discussed below) in the U.S.
wolverine population but not for the Canadian population. Existing
regulatory mechanisms are inadequate to ensure the continued existence
of wolverines in the contiguous United States in the face of these
threats. Therefore, it is our determination that the difference in
conservation status between the two populations is significant in light
of section 4(a)(1)(D) of the Act, because existing regulatory
mechanisms appear sufficient to maintain the robust conservation status
of the Canadian population, while existing regulatory mechanisms in the
contiguous United States are insufficient to protect the wolverine from
threats due to its depleted conservation status. As a result, the
contiguous United States population of the wolverine meets the
discreteness criterion in our DPS Policy (61 FR 4725). Consequently, we
use the international border between the United States and Canada to
define the northern boundary of the contiguous United States wolverine
DPS.
Analysis for Significance
If we determine a population segment is discrete, its biological
and ecological significance will then be considered in light of
Congressional guidance that the authority to list DPSs be used
sparingly while encouraging the conservation of genetic diversity. In
carrying out this examination, we consider available scientific
evidence of the population's importance to the taxon to which it
belongs (i.e., the North American wolverine (Gulo gulo luscus)). Our
DPS policy states that this consideration may include, but is not
limited to: (1) Persistence of the discrete population segment in an
ecological setting unusual or unique for the taxon; (2) evidence that
loss of the discrete population segment would result in a significant
gap in the range of the taxon; (3) evidence that the discrete
population segment represents the only surviving natural occurrence of
a taxon that may be more abundant elsewhere as an introduced population
outside its historical range; or (4) evidence that the discrete
population segment differs markedly from other populations of the
species in its genetic characteristics.
In our 12-month finding (75 FR 78030), we conducted an exhaustive
analysis of the significance of the contiguous United States population
of the North American wolverine that we incorporate here by reference.
In that analysis we concluded that the wolverine population in the
contiguous United States is significant because its
[[Page 7874]]
loss would result in a significant gap in the range of the taxon.
Summary of the Distinct Population Segment Analysis
We conclude that the wolverine population in the contiguous United
States is both discrete and significant under our DPS policy. The
conservation status of wolverines in the contiguous United States is
less secure than wolverines in adjacent Canada due to fragmented
habitat, small population size, reduced genetic diversity, and their
vulnerability to threats analyzed in this finding. Loss of the
contiguous United States wolverines would result in a significant gap
in the range of the taxon. Therefore, we determine that the population
of wolverines in the contiguous 48 States, as currently described,
meets both the discreteness and significance criteria of our DPS
policy, and is a listable entity under the Act as a DPS.
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 any of the following 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; and (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) 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 is discussed under Factor A because
although climate change may affect wolverines directly by creating
physiological stress, the primary impact of climate change on
wolverines is expected to be through changes to the availability and
distribution of wolverine habitat.
Two efforts to map wolverine habitat in the contiguous United
States have been completed (Inman et al. 2012, entire; Copeland et al.
2010, entire). Both of these habitat models rely on snow as a primary
input. The Copeland et al. (2010) model defines wolverine habitat as
simply the area continuously covered by snow from mid-winter until mid-
May. The Inman et al. (2012) model is based on snowpack and also
incorporates other habitat variables, such as terrain ruggedness and
some aspects of human development. The two models result in estimates
of wolverine habitat that are very similar across most of the range of
wolverines in the contiguous United States. Areas of significant
departure between the models are the California Sierras and Oregon
Cascades where the Copeland et al. (2010) model predicts significantly
greater habitat area than does the Inman et al. (2012) model. Given the
general agreement between the two models, we combined the areas
depicted by them into a composite wolverine habitat model that includes
all areas described by one or both of these models. This composite
model serves as the basis for our estimates of wolverine habitat below.
Within the four States that currently harbor wolverines (Montana,
Idaho, Oregon (Wallowas) and Wyoming), an estimated 124,014 km\2\
(47,882 mi\2\) of wolverine habitat exists. Habitat in the North
Cascades and Eastern Washington (Kettle Range and associated habitat)
add approximately 20,356 km\2\ (7859 mi\2\). Ninety-four percent
(135,396 km\2\; 52,277 mi\2\) of total wolverine habitat is in Federal
ownership with most of that managed by the U.S. Forest Service (Forest
Service).
Reduction in Habitat Due to Climate Change
Our analyses under the Act include consideration 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 2007, p. 78). 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 2007, p. 78).
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 climate change, including the role of natural variability in
climate. In our analysis, we rely 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
five analyses that relate the effects of climate changes directly to
wolverines (Gonzalez et al. 2008, entire; Brodie and Post 2009, entire;
Peacock 2011, entire; McKelvey et al. 2011, entire, Johnston et al.
2012, entire). To date, McKelvey et al. (2011) is the most
sophisticated analysis regarding climate change effects to wolverines.
This report is based on data from global climate models including both
temperature and precipitation, downscaled to reflect the regional
climate patterns and topography found within the range of wolverines in
the contiguous United States. For this reason we find that McKelvey et
al. (2011, entire) represents the best scientific information available
regarding the impacts of climate change to wolverine habitat.
Snowpack changes as well as concomitant changes to wolverine
habitat suitability result from both changes in temperature (negative
relationship) and changes in snowfall (positive relationship). Because
many climate models predict higher precipitation levels associated with
climate warming, the interaction between these two variables can be
quite complex. Consequently, predictions about snow coverage that rely
only on temperature projections are less reliable than those that rely
on both temperature and precipitation. McKelvey et al. (2011, entire)
report projections for wolverine habitat and dispersal routes through
the time interval from 2070 to 2099.
Climate Effects to Wolverines
Due to dependence of wolverines on deep snow that persists into
late spring both for successful reproduction and for year-round
habitat, and their restricted distribution to areas that maintain
significant snow late into the spring season, we conclude that deep
snow maintained through the denning period is required for wolverines
to
[[Page 7875]]
successfully live and reproduce. Reduction of this habitat feature
would proportionally reduce wolverine habitat, or to an even greater
extent if habitat reduction involved increasing fragmentation.
Based on the information described above, we analyzed the effects
of climate change on wolverines through three primary mechanisms: (1)
Reduced snowpack and earlier spring runoff, which 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 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 elevation band that
wolverines use into higher elevation. Due to the conical structure of
mountains, this upward shift would result in reduced overall suitable
habitat for wolverines.
Reduced Snow Pack and Earlier Spring Runoff
Warmer winter temperatures are reducing snow pack in western North
American mountains through a higher proportion of precipitation falling
as rain and higher rates of snowmelt during winter (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).
This trend is expected to continue with future warming (Hamlet and
Lettenmaier 1999, p. 1611; Christensen et al. 2004, p. 347; Mote et al.
2005, p. 48). Shifts in the initiation of spring runoff toward earlier
dates are also well documented (Hamlet and Lettenmaier 1999, p. 1609;
Brown 2000, p. 2347; Cayan et al. 2001, pp. 409-410; Christensen et al.
2004, p. 347; Mote et al. 2005, p. 41; Knowles et al. 2006, p. 4554).
Earlier spring runoff leads to lack of snow or degraded snow conditions
during April and May, the critical time period for wolverine
reproductive denning. In addition, a feedback effect hastens the loss
of snow cover due to the reflective nature of snow and the relative
heat-absorbing properties of non-snow-covered ground. This effect leads
to the highest magnitude of warming occurring at the interface of snow-
covered and exposed areas, increasing the rate at which melting occurs
in spring (Groisman et al. 1994a, pp. 1637-1648; Groisman et al. 1994b,
pp. 198-200). Due to the importance of deep snow cover in spring for
wolverine reproduction, currently suitable habitat that loses this
feature would be rendered unsuitable for wolverines.
Ecosystem Changes Associated with Climate Change
Changes in temperature and rainfall patterns are expected to shift
the distribution of ecosystems northward (IPCC 2007c, p. 230) and up
mountain slopes (McDonald and Brown 1992, pp. 411-412; Danby and Hik
2007, pp. 358-359; IPCC 2007c, p. 232). As climate changes over a
landscape, the ecosystems that support wolverines are likely to move
according to the change of temperature, but with a time lag depending
on the ability of individual plant species to migrate (McDonald and
Brown 1992, pp. 413-414; Hall and Fagre 2003, p. 138; Peterson 2003, p.
652). Wolverines are not dependent on any particular ecosystem in the
sense that they do not appear to depend on a certain vegetative
component or other biological ecosystem attribute; however, it is
likely that wolverines would respond to similar climatic cues as other
members of the alpine ecosystem such that changes in tree-line location
up or down slope would predict a similar change in wolverine
distribution. Because of their reliance on mountainous habitat,
wolverines in the contiguous United States will most likely adjust to
climate changes by using higher elevations on mountain slopes, not by
shifting their latitudinal distribution. Along a latitudinal gradient
through the historical distribution of wolverines, records tend to be
found at higher elevations in southern latitudes (Aubry et al. 2007, p.
2153), suggesting that wolverines compensate for increased temperature
at low latitudes by selecting higher elevations. Therefore, the
regional availability of suitable habitat is not likely to
significantly change (i.e., at least some wolverine habitat will
continue to be available in all regions where wolverines currently
occur), but within these landscapes, smaller areas will remain suitable
for wolverines. Mountain ranges with maximum elevations within the
elevation band that wolverines currently use, such as much of the
wolverine habitat in central Idaho, may become entirely unsuitable for
wolverines with the projected level of warming reported in McKelvey et
al. (2011, Figure 3; see below for discussion).
Timing of Climate Effects
Unlike snow conditions, which respond directly to temperature
change without a time lag, ecosystem responses to temperature change do
lag, with the magnitude of the lag depending on constituent species'
individual migratory abilities. Wolverines are described as a ``tree-
line'' species because they are most often found in an elevation band
that is approximately centered on the alpine tree-line at any given
locality within their range (Inman et al. 2012a, p. 785). Alpine tree
lines are maintained by a complex set of climactic and biotic factors,
of which temperature is significantly important (Cogbill and White
1991, p. 169; H[auml]ttenschwiler and K[ouml]rner 1995, p. 367;
Jobb[aacute]gy and Jackson 2000, p. 259; Pellat et al. 2000, pp. 80-
81). However, the conditions that favor tree establishment and lead to
elevation advance in the tree line may exist only sporadically,
increasing time lags associated with tree line response to warming
beyond the species-specific generation time of the trees involved
(Hessl and Baker 1997, p. 181; Klasner and Fagre 2002, p. 54). Within
wolverine habitats, tree lines have advanced up mountain slopes since
1850, due to climate warming, and this trend is expected to continue
into the future (Hessl and Baker 1997, p. 176; Hall and Fagre 2003, p.
138). We expect that species reliant on resources associated with this
biome, such as wolverines, will need to shift accordingly, not
necessarily due to their dependence on the specific vegetation
conditions, but due to wolverines likely being keyed into similar
climatic variables. Since wolverine association with tree-line location
is likely coincident with their dependence on climatic conditions, and
the fact that wolverines can move about in response to climate changes,
it is not likely that wolverines would respond to climate changes with
a similar time lag. More likely, wolverines would respond to climate
changes in real time, shifting habitat use more rapidly than tree-line
shifts would occur. Given the irregular nature of tree-line response to
warming, tree-line migration is likely to lag behind the climate
warming that causes it.
Magnitude of Climate Effects on Wolverine
Several studies relating the effects of climate changes on
wolverines in the past, present, and future are now available (Brock
and Inman Personal Communication 2007, entire; Gonzales et al. 2008,
pp. 1-5; Brodie and Post 2010, entire; McKelvey et al. 2011, entire;
Peacock 2011, entire; Johnston et al. 2012, entire). The Gonzalez et
al. report and the report by Brock and Inman (Personal Communication
2007) were both preliminary attempts to
[[Page 7876]]
analyze climate change impacts to wolverines, but are not currently
considered the best available science because they did not consider the
effects of both changes in temperature and precipitation that may
affect the distribution of persistent spring snow cover (McKelvey 2011,
entire). The analysis by Peacock (2011) is a sophisticated look at
climate change impacts to wolverines, but suffers from the large-scale
data presentation used. This large scale makes relating specific
impacts to wolverines difficult, because the montane habitat inhabited
by wolverines is climatologically complex on a small scale, and without
significant downscaling of climate results, it is not possible to
determine how much habitat may be left after climate change impacts
have occurred. Both Brock and Inman (Personal Communication 2007) and
Gonzalez et al. (2008) have been superseded by a more sophisticated
analysis provided by McKelvey et al. (2011, entire). The course-grain
scale of the analysis in Peacock (2011, entire) limits its use to that
of supporting the conclusion that wolverine habitat is likely to
decline. Likewise, the limited area analyzed by Johnston et al. (2012)
also limits its use for this wide-ranging species. The McKelvey et al.
(2011, entire) analysis includes climate projections at a local scale
for wolverine habitats and analyzes the effects of both temperature
changes and changes to precipitation patterns. Lack of accounting for
changes in precipitation was a weakness of their own work cited by the
authors of both Brock and Inman (Personal Communication 2007) and
Gonzalez et al. (2008).
Brodie and Post (2010, entire) correlate the decline in wolverine
populations in Canada over the past century with declining snowpack due
to climate change over the same period. However, correlation does not
infer causation; other factors could have caused the decline. The
Brodie and Post (2010, entire) analysis used harvest data to infer
population trends in addition to its reliance on correlation to infer
causation (McKelvey et al. 2010a, entire); in this case, historic
climate changes are inferred to have caused the declines in harvest
returns, which are thought by the authors to reflect actual population
declines. Due to the above-stated concerns, we view the analysis of
Brodie and Post (2010, entire) with caution, although we do agree that
the posited mechanism, of loss of snowpack affecting wolverine
populations and distribution, likely has merit.
McKelvey et al. (2011, entire) used downscaled global climate
models to project the impacts of changes in temperature and
precipitation to wolverine habitat as modeled by Copeland et al. (2010,
entire). The authors also present an alternative method for evaluating
climate impacts on wolverine habitat, by merely projecting onset of
spring snowmelt to occur 2 weeks earlier than it currently does. Based
on this information, wolverine habitat in the contiguous United States,
which supports approximately 250 to 300 wolverines, is shrinking and is
likely to continue to shrink with increased climate warming (McKelvey
et al. 2011, Figure 4). Habitat losses are likely to occur throughout
the range of the DPS and are projected to be most severe in central
Idaho. However, large areas of snow cover are likely to remain in the
North Cascades, Greater Yellowstone Area (GYA), and the Glacier Park-
Bob Marshall Wilderness of Montana (McKelvey et al. 2011 Figures 4,
13). The southern Rocky Mountains of Colorado retained significant
high-elevation snow in some models but not others, and so may be
another area that could support wolverine populations in the face of
climate changes (McKelvey et al. 2011, p. 2889).
Overall, wolverine habitat in the contiguous United States is
expected to get smaller and more highly fragmented as individual
habitat islands become smaller and the intervening areas between
wolverine habitats become larger (McKelvey et al. 2011, Figures 4, 13).
McKelvey et al. (2011) predict that 31 percent of current wolverine
habitat in the contiguous United States will be lost due to climate
warming by the time interval centered on 2045 (2030-2059) (McKelvey et
al. 2011, pp. 2887-2888). That loss expands to 63 percent of wolverine
habitat by the time interval centered on 2085 (2070 to 2099). Estimates
for the northern Rocky Mountain States (Montana, Idaho, and Wyoming)
are similar, with an estimated 32 percent and 63 percent of persistent
spring snow lost for the 2045 and 2085 intervals respectively. Central
Idaho is predicted to be especially sensitive to climate change effects
losing 43 percent and 78 percent of wolverine habitat for the 2045 and
2085 intervals respectively. Conversely, the mountains of Colorado
appear to be slightly less sensitive to climate changes in their
analysis losing 31 percent and 57 percent of habitat over the same
intervals. Given the spatial needs of wolverines and the limited
availability of suitable wolverine habitat in the contiguous United
States, this projected gross loss of habitat area is likely to result
in a loss of wolverine numbers that is greater than the overall loss of
habitat area.
We expect wolverine populations to be negatively affected by
changes in the spatial distribution of habitat patches as remaining
habitat islands become progressively more isolated from each other due
to climate changes (McKelvey et al. 2011, Figure 8). Currently,
wolverine habitat in the contiguous United States can be described as a
series of habitat islands. Some of these groups of islands are large
and clumped closely together, such as in the North Cascades, Glacier
Park-Bob Marshall Wilderness complex in Montana, and the GYA. Other
islands are smaller and more isolated, such as the island mountain
ranges of central and southwestern Montana. Inbreeding and consequent
loss of genetic diversity have occurred in the past within these
smaller islands of habitat (Cegelski et al. 2006, p. 208), and genetic
exchange between subpopulations is difficult to achieve (Schwartz et
al. 2009, Figure 4). Climate change projections indicate that, as
warming continues, large contiguous blocks of habitat will decrease in
size and become isolated to the extent that their ability to support
robust populations becomes questionable (McKelvey et al. 2010b, Figure
8). Under the moderate climate change scenarios analyzed by McKelvey et
al. (2011, entire), the current wolverine stronghold in central Idaho
begins to look similar to the current situation in the more isolated
mountain ranges of southwestern Montana (McKelvey et al. 2011, Figure
4) where wolverines persist, but subpopulations are small. These
subpopulations are essentially family groups, which require
connectivity with other groups for genetic and possibly demographic
enrichment. This habitat alteration would result in a high likelihood
of reduced genetic diversity due to inbreeding within a few generations
(Cegelski et al. 2006, p. 209). Further isolation of wolverines on
small habitat islands with reduced connectivity to other subpopulations
would also increase the likelihood of subpopulations loss due to
demographic stochasticity, impairing the functionality of the wolverine
metapopulation in the contiguous United States.
We find that McKelvey et al. (2011, entire) represents the best
available science for projecting the future impacts of climate change
on wolverine habitat for four primary reasons. First, their habitat
projections are based on global climate models that are thought to be
the most reliable predictors of future climate available (IPCC 2007a,
p. 12).
[[Page 7877]]
Second, they conducted downscaling analyses to infer geographic climate
variation at a scale relevant to wolverine habitat. Third, they used a
hydrologic model to predict snow coverage during the spring denning
period (the strongest correlate with wolverine reproductive success).
Fourth, they used the habitat model developed by Copeland et al. (2010,
entire), to relate projected climate changes to wolverine habitat.
Based on our analysis of the methods and analysis used by the authors,
we conclude it constitutes the best available information on the likely
impact of climate change on wolverine distribution in the contiguous
United States. Other analyses of climate change discussed above (Brock
and Inman Personal Communication 2007, entire; Gonzales et al. 2008,
entire; Brodie and Post 2010, entire; Peacock 2011, entire) all support
the conclusion that climate changes caused by warming are likely to
negatively affect wolverine habitat in the future. Based on the
analysis presented, we conclude that climate changes are likely to
result in permanent loss of a significant portion of wolverine habitat
in the future. Additional impacts of climate change will be increased
habitat fragmentation as habitat islands become smaller and intervening
habitat disappears. Eventually, habitat fragmentation will likely lead
to a breakdown of wolverine metapopulation dynamics, as subpopulations
are no longer able to rescue each other after local extinctions due to
a lack of connectivity. It is also likely that loss of genetic
diversity resulting in lower fitness will occur as population isolation
increases.
Summary of Impacts of Climate Changes
Wolverine habitat is projected to decrease in area and become more
fragmented in the future as a result of climate changes that result in
increasing temperatures, earlier spring snowmelt, and loss of deep,
persistent, spring snowpack. These climate change impacts are expected
to have direct and indirect effects to wolverine populations in the
contiguous United States including reducing the number of wolverines
that can be supported by available habitat and reducing the ability of
wolverines to travel between patches of suitable habitat. This
reduction in population size and connectivity is likely to affect
metapopulation dynamics, making it more difficult for subpopulations to
recolonize areas where wolverines have been extirpated and to bolster
the genetics or demographics of adjacent subpopulations.
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 species' ability to tolerate
and adapt to repeated human disturbance. Some speculate 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 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 rulemaking, 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)
[[Page 7878]]
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
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 United States
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
rigorous 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, p. 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 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). However, gene flow between wolverine subpopulations in the
contiguous United States may not be high enough to prevent genetic
drift (Cegelski et al. 2006, p. 208). To ensure long-term genetic
viability, each subpopulation
[[Page 7879]]
within the contiguous United States would need an estimated 400
breeding pairs, or 1 to 2 effective migrants per generation (Cegelski
et al. 2006, p. 209). Our current understanding of wolverine ecology
suggests that no subpopulation historically or presently at carrying
capacity would approach 400 breeding pairs within the contiguous United
States (Brock et al. 2007, p. 26); nor is the habitat capable of
supporting anywhere near this number. It is highly unlikely that 400
breeding pairs exist in the entire contiguous United States. Because no
wolverine subpopulations are likely to be large enough to maintain
genetic diversity over time on their own, long-term viability of
wolverines in the contiguous United States requires exchange of
individuals between subpopulations.
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
also 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
crossings of Federal or State highways were done by subadult wolverines
making exploratory or dispersal movements (ranges of resident adults
typically did 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, p. 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, p. 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, 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 (see Factor D for
more discussion) 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 species.
Summary of Factor A
The threat of current, and future impacts to wolverine habitat due
to climate change occurs over the entire range of the contiguous United
States
[[Page 7880]]
population of the wolverine. This threat is likely to have already
reduced the overall areal extent and distribution of wolverine suitable
habitat. Determining whether or not wolverine populations have been
impacted by this threat is complicated by the historical extirpation of
wolverines in the early 20th century followed by recolonization and
expansion. It is possible that expansion of wolverine populations
through the second half of the 20th century has masked climate change
effects that would have otherwise reduced populations had they existed
at presettlement levels. Despite the lack of detectable population-
level impacts, it is still likely that habitat is already reduced from
historic levels due to this threat.
Suitable wolverine habitat is projected to be reduced by 31 percent
in the contiguous United States by 2045 and 63 percent by the time
interval 2070 to 2099 due to climate warming. This reduction will
likely result in suitable wolverine habitat shifting up mountain
slopes, and becoming smaller and more isolated due to the conical
structure of mountains. Because wolverine home ranges tend to be so
large, some small mountain ranges are likely to lose the ability to
support wolverine populations. We expect that the secondary effects of
this habitat loss, such as increased habitat fragmentation and
isolation, will intensify the overall impacts of habitat loss on
wolverines.
Deep snow that persists into the month of May is essential for
wolverine reproduction. This life-history parameter for the species
(reproductive rate) is likely to be most sensitive to climate changes.
Wolverine are vulnerable to habitat modification (specifically,
reduction in persistent spring snow cover) due to climate warming in
the contiguous United States. Further, it is likely that year-round
wolverine habitat, not just denning habitat, will also be significantly
reduced due to the effects of climate warming. Reductions in habitat
would result in greater habitat isolation, thereby likely reducing the
frequency of dispersal between habitat patches and the likelihood of
recolonization after local extinction events. This reduced dispersal
ability, if not compensated for by higher population levels or assisted
dispersal, is likely to result in loss of genetic diversity within
remaining habitat patches and population loss due to demographic
stochasticity. The contiguous United States population of wolverines is
already very small and fragmented and is, therefore, particularly
vulnerable to these impacts.
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 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, the best scientific and commercial information
available indicates that only the projected decrease and fragmentation
of wolverine habitat or range due to future climate change is a threat
to the species now and in the future. The 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).
Human-caused mortality of wolverines is likely additive to natural
mortality due to the low reproductive rate and relatively long life
expectancy of wolverines (Krebs et al. 2004, p. 499; Lofroth and Ott
2007, pp. 2197-2198; Squires et al. 2007, pp. 2218-2219). This means
that trapped subpopulations likely live at densities that are lower
than carrying capacity, and may need to be reinforced by recruits from
untrapped subpopulations to maintain population viability and
persistence.
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 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
[[Page 7881]]
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 wolverine home
ranges extended into large areas outside the park (Squires et al. 2007,
p. 2219). It is likely that the largerscale 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 threat within most of the wolverine 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. In the four trapping seasons that have occurred since
these rules were implemented, wolverine take averaged 3.25 wolverines
annually (Montana Department of Fish Wildlife and Parks 2010, pp. 8-11;
Brian Giddings Pers. Comm. August 30, 2012), with reduced harvest being
due to season closure rather than lack of wolverines. Under the current
regulations, no more than three female wolverines can be legally
harvested each year, and harvest in the more vulnerable isolated
mountain ranges is prohibited. 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 (Bob Inman pers. comm. 2010b).
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
described in the geographic distribution section, and we have not
relied on this information in this finding.
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.
Current levels of incidental trapping (i.e., capture in traps set
for species other than wolverine) have been suggested by the
petitioners to be a threat to 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.
Four cases of incidental wolverine trapping have occurred in Idaho in
recent years. One wolverine was trapped by a coyote/bobcat trapper in
2006 and was collared and released after all of its toes and a portion
of its left front foot were amputated (Inman et al. 2008, p. 1). That
animal (a female) survived and successfully reproduced after release.
The Department of Agriculture 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. 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 affects populations
occurring outside of Montana is unknown. However, the State of Montana
contains most 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. Harvest,when combined with the likely
effects of climate change, may contribute to the likelihood that the
wolverine will become extirpated in the
[[Page 7882]]
future. This may occur by increasing the speed with which small
populations of wolverine are lost from isolated habitats, and also by
increasing mortality levels for dispersing wolverines, with the result
of reducing dispersal rates. Regular dispersal and exchange of genetic
material are required to maintain the genetics and demographics of
wolverine subpopulations in the contiguous United States.
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 would not be a
threat to the wolverine DPS. However, by working in concert with
habitat loss resulting from climate change, mortality due to harvest
and incidental trapping may contribute to population declines.
Therefore, we conclude that trapping, when considered cumulatively with
habitat loss resulting from climate change, is likely to become a
threat to the DPS (see discussion under Synergistic Interactions
Between Threat Factors, below).
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
lion (Burkholder 1962, p. 264; Hornocker and Hash 1981, p. 1296;
Copeland 1996, p. 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 North America 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 species now or likely to become so
in the future.
Factor D. Inadequacy of Existing Regulatory Mechanisms
Based on our calculations using a composite map showing the
coverage of both the Copeland et al. (2010, entire) and Inman et al.
(2012, entire) wolverine habitat models, the majority (94 percent) of
wolverine habitat currently occupied by wolverine populations in the
lower contiguous United States is Federally owned and managed, mostly
by the U.S. Forest Service. An estimated 144,371 km\2\ (49,258 mi\2\)
of wolverine habitat occurs in the occupied area in Montana, Idaho,
Oregon (Wallowa Range), and Wyoming. Of that, 135,396 km\2\ (46,332
mi\2\) is in Federal ownership. Additionally, 47,150 km\2\ (12,973
mi\2\) (32.7 percent) occurs in designated wilderness, and 23,062 km\2\
(1,630 mi\2\) (16.0 percent) occurs in inventoried roadless areas. An
additional 13,784 km\2\ (3,288 mi\2\) (9.5 percent) are within national
parks.
None of the existing Federal or State regulatory mechanisms were
designed to address the threat of modification of wolverine habitat due
to the loss of snowpack associated with climate change. Several
existing regulatory mechanisms protect wolverine from other forms of
disturbance and from overutilization from harvesting; these are
described in more detail below.
Federal Laws and Regulations
The Wilderness Act
The 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 personal communication
2007b). As such, a large proportion of existing wolverine habitat is
protected from direct loss or degradation by the prohibitions of the
Wilderness Act.
National Environmental Policy Act
All Federal agencies are required to adhere to the National
Environmental Policy Act (NEPA) of 1970 (42 U.S.C. 4321 et seq.) for
projects they fund, authorize, or carry out. The Council on
Environmental Quality's regulations for implementing NEPA (40 CFR 1500-
1518) state that agencies shall include a discussion on the
environmental impacts of the various project alternatives (including
the proposed action), any adverse environmental effects which cannot be
avoided, and any irreversible or irretrievable commitments of resources
involved (40 CFR 1502). The NEPA itself is a disclosure law, and does
not require subsequent minimization or mitigation measures by the
Federal agency involved. Although Federal agencies may include
conservation measures for wolverines as a result of the NEPA process,
any such measures are typically voluntary in nature and are not
required by the statute. Additionally, activities on non-Federal lands
are subject to NEPA if there is a Federal action.
For example, wolverines are designated as a sensitive species by
the Forest Service, which requires that effects to wolverines be
considered in documentation completed under NEPA. NEPA does not itself
regulate activities that might affect wolverines, but it does require
full evaluation and disclosure of information regarding the effects of
contemplated Federal actions on sensitive species and their habitats.
National Forest Management Act
Under the National Forest Management Act of 1976, as amended (16
U.S.C. 1600-1614), the Forest Service shall strive to provide for a
diversity of plant and animal communities when managing national forest
lands. Individual national forests may identify species of concern that
are significant to each forest's biodiversity. Outside of designated
wilderness but still on Forest Service-managed lands, wolverines occur
mainly in alpine areas. Their habitat is generally offered more
protections from timber harvest than would otherwise be the case in
lowland areas due to the difficulty of accessing wolverine habitat,
especially in areas where motorized access is limited or absent, such
as most National Forest land and all designated wilderness areas.
National Park Service Organic Act
The NPS Organic Act of 1916 (16 U.S.C. 1 et seq.), as amended,
states that the NPS ``shall promote and regulate the use of the Federal
areas known as
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national parks, monuments, and reservations to conserve the scenery and
the national and historic objects and the wildlife therein and to
provide for the enjoyment of the same in such manner and by such means
as will leave them unimpaired for the enjoyment of future
generations.'' Where wolverines occur in National Parks, they and their
habitats are protected from large-scale loss or degradation due to the
Park Service's mandate to ``* * * conserve scenery * * * and wildlife *
* * [by leaving] them unimpaired.'' Wolverine harvest and trapping of
other furbearers is also prohibited in National Parks.
Clean Air Act of 1970
On December 15, 2009, the Environmental Protection Agency (EPA)
published in the Federal Register (74 FR 66496) a rule titled,
``Endangerment and Cause or Contribute Findings for Greenhouse Gases
under Section 202(a) of the Clean Air Act.'' In this rule, the EPA
Administrator found that the current and projected concentrations of
the six long-lived and directly emitted greenhouse gases (GHGs)--carbon
dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons,
and sulfur hexafluoride--in the atmosphere threaten the public health
and welfare of current and future generations; and that the combined
emissions of these GHGs from new motor vehicles and new motor vehicle
engines contribute to the GHG pollution that threatens public health
and welfare (74 FR 66496). In effect, the EPA has concluded that the
GHGs linked to climate change are pollutants, whose emissions can now
be subject to the Clean Air Act (42 U.S.C. 7401 et seq.) (see 74 FR
66496). However, specific regulations to limit GHG emissions were only
proposed in 2010 and, therefore, cannot be considered an existing
regulatory mechanism. At present, we have no basis to conclude that
implementation of the Clean Air Act in the future (40 years, based on
global climate projections) will substantially reduce the current rate
of global climate change through regulation of GHG emissions. Thus, we
conclude the Clean Air Act is not designed to address the primary
threat to wolverine of the loss of snowpack due to the effects of
climate change.
State Laws and Regulations
State Comprehensive Wildlife Conservation Strategies and State
Environmental Policy and Protection Acts
The wolverine is listed as State Endangered in Washington,
California, and Colorado. In Idaho and Wyoming it is designated as a
protected nongame species (Idaho Department of Fish and Game 2010, p.
4; Wyoming Game and Fish 2005, p. 2). Oregon, while currently not
considered to have any individuals other than possible unsuccessful
dispersers, has a closed season on trapping of wolverines. These
designations largely protect the wolverine from mortality due to
hunting and trapping. In Montana, the wolverine is classified as a
regulated furbearer (Montana Fish, Wildlife, and Parks 2010, p. 8).
Montana is the only State in the contiguous United States where
wolverine trapping is still legal.
Wolverines receive some protection under State laws in Washington,
California, Idaho, Montana, Wyoming, and Colorado. Each State's fish
and wildlife agency has some version of a State Comprehensive Wildlife
Conservation Strategy (CWCS) in place. These strategies, while not
State or Federal legislation, can help prioritize conservation actions
within each State. Named species and habitats within each CWCS may
receive focused attention during State Environmental Protection Act
(SEPA) reviews as a result of being included in a State's CWCS.
However, only Washington, California, and Montana appear to have SEPA-
type regulations in place. In addition, each State's fish and wildlife
agency often specifically names or implies protection of wolverines in
its hunting and trapping regulations. Only the State of Montana
currently allows wolverine harvest (see discussion under Factor B).
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. Under factor B, above, we
concluded that trapping, including known rates of incidental trapping
in Montana, by itself, is not a threat to the wolverine DPS, but that
by working in concert with the primary threat of climate change, the
trapping program may contribute to population declines (see Synergistic
Interactions Between Threat Factors, below).
Summary of Factor D
The existing regulatory mechanisms appear to protect wolverine from
several of the factors described in Factors A and B above.
Specifically, State regulations for wolverine harvest appear to be
sufficient to prohibit range-wide overutilization from hunting and
trapping in the absence of other threats. However, given that climate
change impacts are expected to reduce wolverine populations and
fragment habitat, the impact of harvest to wolverine would be expected
to increase if harvest levels were maintained at current levels.
Federal ownership of much of occupied wolverine habitat protects the
species from direct losses of habitat and provides further protection
from many of the forms of disturbance described above. Wolverines use
habitats affected by human disturbance, and additional protection is
afforded wolverines by the large area of their range that occurs in
designated wilderness and national parks. The current regulatory regime
does not address the potential impacts of dispersed winter recreation
outside of protected areas; however, at this time the available
information does not suggest that dispersed winter recreation is a
threat to the DPS.
Our review of the regulatory mechanisms in place at the national
and State level demonstrates that the short-term, site-specific threats
to wolverine from direct loss of habitat, disturbance by humans, and
direct mortality from hunting and trapping are, for the most part,
adequately addressed through State and Federal regulatory mechanisms.
However, as described under Factor A, the primary threat with the
greatest severity and magnitude of impact to the species is loss of
habitat due to continuing climate warming. The existing regulatory
mechanisms currently in place at the national level were not designed
to address the threat to wolverine habitat from climate change.
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.
[[Page 7884]]
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 high-quality home ranges
are limited, and individuals occupying them 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 1 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 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, p. 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 (for
appropriate use of this rule and its limitations see Allendorf and
Luikart 2007, pp. 359-360). Others suggest that even higher numbers are
required to ensure that populations remain viable, suggesting that
long-term connectivity to the reservoir of genetic resources in the
Canadian population of wolverines will be required for the long-term
genetic health of the DPS (Traill et al. 2010, p. 32). All evidence
suggests that no habitat area within the contiguous United States is
large enough to support a wolverine population with an effective
population size of 500 animals. 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 viability.
Wolverine effective population size in the northern Rocky
Mountains, which is the largest extant population in the contiguous
United States, is exceptionally 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.
For comparison, estimates of wolverine effective population size are
bracketed by critically endangered species, such as the black-footed
ferret (Mustela nigripes) (4.10) (Wisely et al. 2007, p. 3) and the
ocelot (Leopardus pardalis) (2.9 to 13.9) (Janecka et al. 2007, p. 1),
but are substantially smaller than estimates for the Yellowstone
grizzly bear (Ursus arctos) (greater than 100), which has reached the
level of recovery under the Act (Miller and Waits 2003, p. 4338).
Therefore, we conclude that effective population size estimates for
wolverines do not suggest that populations are currently critically
endangered, but they do suggest that populations are low enough that
they could be vulnerable to loss of genetic diversity, and may require
intervention in the future to remain viable. To date, no adverse
effects of the lower genetic diversity of the contiguous United States
wolverines have been documented.
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. The concern that low effective population size would
result in negative effects is already being realized for the contiguous
United States population of wolverine. Genetic drift has already
occurred in subpopulations of the contiguous United States: Wolverines
here contained 3 of 13 haplotypes found
[[Page 7885]]
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).
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 species' ability to persist through reduced 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 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, as predicted due to climate changes.
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, by itself, is not a
threat to the wolverine DPS. However, by working in concert with the
primary threat of habitat loss due to climate change, this may
contribute to the cumulative effect of population declines. Therefore,
we conclude that demographic stochasticity and loss of genetic
diversity due to small effective population sizes is a threat to
wolverines when considered cumulatively with habitat loss due to
climate change (see discussion under Synergistic Interactions Between
Threat Factors).
Synergistic Interactions Between Threat Factors
We have evaluated individual threats to the distinct population
segment of the North American Wolverine throughout its range in the
contiguous United States. The wolverine DPS faces one primary threat
that is likely to drive its conservation status in the future: habitat
change and loss due to climate change. This factor alone is enough to
determine that the species should be proposed for listing under the
Act. Other factors, though not as severe or geographically
comprehensive as the potential habitat effects from climate change may,
when considered in the context of changes likely to occur due to
climate change, become threats due to the cumulative effects they have
on wolverine populations. For wolverines, the only such threat factors
found in our analysis to have a basis of support as threats to
wolverines were the effects of small subpopulation sizes and
subpopulation isolation on wolverine genetic and demographic health,
and the subsequent potential future influence of trapping.
As discussed in our analysis of the effects on wolverine habitat
from climate change under Factor A, wolverine habitat in the contiguous
United States is likely to become smaller overall, and remaining
habitat is likely to be more fragmented and fragments more isolated
from one another than they are today (McKelvey et al. 2011, Figure 8).
Given that wolverine subpopulations in the DPS are already so small,
and movement between subpopulations so restricted, inbreeding has
become likely (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 longterm maintenance of
wolverines in the DPS will require continued connectivity between
subpopulations within the DPS, and with populations to the north in
Canada. To the extent that wolverine habitat becomes more fragmented,
and fragments become more isolated due habitat loss resulting from
climate change, these factors will become more significant to wolverine
conservation. The risk factor of small population size, including
measures of effective population size and their consequent effects on
maintenance of genetic diversity, is a threat to the North American
wolverine DPS when considered cumulatively with habitat loss resulting
from climate change.
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). Most of this expansion has occurred under trapping
regulations that allowed a higher level of trapping than currently
occurs (see Montana Department of Fish, Wildlife, and Parks 2007, p.
1). Therefore, it might be argued that wolverine trapping is not
occurring at levels that would significantly affect conservation of the
DPS. However, future habitat changes due to climate change are
predicted to reduce habitat connectivity and extent. As described
above, these changes are likely to exacerbate the problem of loss of
genetic diversity and demographic stability caused by low effective
population size and insufficient movement between populations, leading
to inbreeding. Given these likely secondary effects of climate change,
human-caused mortality due to harvest is likely to become more
significant to the wolvereine population as connectivity needs increase
and connectivity simultaneously becomes more difficult. As habitats
become
[[Page 7886]]
smaller and more isolated from one another, more wolverines will be
needed to attempt to move between subpopulations to maintain population
viability. Harvest currently removes up to five wolverines from the
population every year, reducing the number of animals available for
dispersal. In addition, incidental trapping of wolverines removes still
more. For these reasons, we find that harvest and incidental trapping,
when considered cumulatively with habitat loss resulting from climate
change, are likely to become threats to the DPS due to the likely
synergistic effects they may have on the population as habitat becomes
smaller and more fragmented.
Proposed Determination
We have carefully assessed the best scientific and commercial
information available regarding the past, present, and future threats
to the wolverine DPS. We have identified threats to the contiguous
United States population of the North American wolverine attributable
to Factors A, B, and E. The primary threat to the DPS is from habitat
and range loss due to climate warming (Factor A). Wolverines require
habitats with near-arctic conditions wherever they occur. In the
contiguous United States, wolverine habitat is restricted to high-
elevation areas in the West. Wolverines are dependent on deep
persistent snow cover for successful denning, and they concentrate
their year-round activities in areas that maintain deep snow into
spring and cool temperatures throughout summer. Wolverines in the
contiguous United States exist as small and semi-isolated
subpopulations in a larger metapopulation that requires regular
dispersal of wolverines between habitat patches to maintain itself.
These dispersers achieve both genetic enrichment and demographic
support of recipient populations. Climate changes are predicted to
reduce wolverine habitat and range by 31 percent over the next 30 years
and 63 percent over the next 75 years, rendering remaining wolverine
habitat significantly smaller and more fragmented. We anticipate that,
by 2045, maintenance of the contiguous United States wolverine
population in the currently occupied area may require human
intervention to facilitate genetic exchange and possibly also to
facilitate metapopulation dynamics by moving individuals between
habitat patches if they are no longer accessed regularly by dispersers,
or risk loss of the population.
Other threats are minor in comparison to the driving primary threat
of climate change; however, cumulatively, they could become significant
when working in concert with climate change if they further suppress an
already stressed population. These secondary threats include harvest
(including incidental harvest) (Factor B) and demographic stochasticity
and loss of genetic diversity due to small effective population sizes
(Factor E). All of these factors affect wolverines across their current
range in the contiguous United States.
The Act defines an endangered species as any species that is ``in
danger of extinction throughout all or a significant portion of its
range'' and a threatened species as any species ``that is likely to
become endangered throughout all or a significant portion of its range
within the foreseeable future.'' We find that the contiguous United
States wolverine DPS presently meets the definition of a threatened
species due to the likelihood of habitat loss caused by climate change
resulting in population decline leading to breakdown of metapopulation
dynamics. Breakdown in metapopulation dynamics would make the DPS
vulnerable to further loss of genetic diversity through inbreeding, and
likely vulnerable to demographic endangerment as small subpopulations
could no longer rely on demographic rescue from nearby populations. At
that point wolverine populations would meet the definition of an
endangered species under the Act. We base this determination on the
immediacy, severity, and scope of the threats described above.
Therefore, on the basis of the best available scientific and commercial
information, we propose listing the contiguous United State DPS of the
North American wolverine as a threatened species in accordance with
sections 3(6) and 4(a)(1) of the Act.
Under the Act and our implementing regulations, a species may
warrant listing if it meets the definition of an endangered or
threatened species throughout all or a significant portion of its
range. The contiguous United States DPS of the North American wolverine
proposed for listing in this rule is wide-ranging and the threats occur
throughout its range. Therefore, we assessed the status of the DPS
throughout its entire range. The threats to the survival of the species
occur throughout the species' range and are not restricted to any
particular significant portion of that range. Accordingly, our
assessment and proposed determination applies to the DPS throughout its
entire range.
Available Conservation Measures
Conservation measures provided to species listed as an endangered
or threatened species under the Act include recognition, recovery
actions, requirements for Federal protection, and prohibitions against
certain practices. Recognition through listing results in public
awareness and conservation by Federal, State, Tribal, and local
agencies, private organizations, and individuals. The Act encourages
cooperation with the States and requires that recovery actions be
carried out for all listed species. The protection required by Federal
agencies and the prohibitions against certain activities are discussed,
in part, below.
The primary purpose of the Act is the conservation of endangered
and threatened species and the ecosystems upon which they depend. The
ultimate goal of such conservation efforts is the recovery of these
listed species, so that they no longer need the protective measures of
the Act. Subsection 4(f) of the Act requires the Service to develop and
implement recovery plans for the conservation of endangered and
threatened species. The recovery planning process involves the
identification of actions that are necessary to halt or reverse the
species' decline by addressing the threats to its survival and
recovery. The goal of this process is to restore listed species to a
point where they are secure, self-sustaining, and functioning
components of their ecosystems.
Recovery planning includes the development of a recovery outline
shortly after a species is listed, preparation of a draft and final
recovery plan, and revisions to the plan as significant new information
becomes available. The recovery outline guides the immediate
implementation of urgent recovery actions and describes the process to
be used to develop a recovery plan. The recovery plan identifies site-
specific management actions that will achieve recovery of the species,
measurable criteria that determine when a species may be downlisted or
delisted, and methods for monitoring recovery progress. Recovery plans
also establish a framework for agencies to coordinate their recovery
efforts and provide estimates of the cost of implementing recovery
tasks. Recovery teams (composed of species experts, Federal and State
agencies, nongovernmental organizations, and stakeholders) are often
established to develop recovery plans. The recovery outline is
available on our Web site at http://www.fws.gov/mountain-prairie/species/mammals/wolverine/ and on http://
[[Page 7887]]
www.regulations.gov concurrently with the publication of this proposed
rule. When completed, the draft recovery plan and the final recovery
plan will be available on our Web site or from our Montana Ecological
Services Field Office (see FOR FURTHER INFORMATION CONTACT).
Implementation of recovery actions generally requires the
participation of a broad range of partners, including other Federal
agencies, States, Tribal, nongovernmental organizations, businesses,
and private landowners. Examples of recovery actions include habitat
restoration (e.g., restoration of native vegetation), research, captive
propagation and reintroduction, and outreach and education. The
recovery of many listed species cannot be accomplished solely on
Federal lands because their range may occur primarily or solely on non-
Federal lands. To achieve recovery of these species requires
cooperative conservation efforts on private, State, and Tribal lands.
If this species is listed, funding for recovery actions will be
available from a variety of sources, including Federal budgets, State
programs, and cost share grants for nonfederal landowners, the academic
community, and nongovernmental organizations. In addition, pursuant to
section 6 of the Act, the States inhabited by wolverines or uninhabited
states with suitable habitat would be eligible for Federal funds to
implement management actions that promote the protection and recovery
of wolverines. Information on our grant programs that are available to
aid species recovery can be found at: http://www.fws.gov/grants.
Although the wolverine DPS is only proposed for listing under the
Act at this time, please let us know if you are interested in
participating in recovery efforts for this species. Additionally, we
invite you to submit any new information on this species whenever it
becomes available and any information you may have for recovery
planning purposes (see FOR FURTHER INFORMATION CONTACT).
Section 7(a) of the Act requires Federal agencies to evaluate their
actions with respect to any species that is proposed or listed as
endangered or threatened and with respect to its critical habitat, if
any is designated. Regulations implementing this interagency
cooperation provision of the Act are codified at 50 CFR part 402.
Section 7(a)(4) of the Act requires Federal agencies to confer with the
Service on any action that is likely to jeopardize the continued
existence of a species proposed for listing or result in destruction or
adverse modification of proposed critical habitat. If a species is
listed subsequently, section 7(a)(2) of the Act requires Federal
agencies to ensure that activities they authorize, fund, or carry out
are not likely to jeopardize the continued existence of the species or
destroy or adversely modify its critical habitat. If a Federal action
may affect a listed species or its critical habitat, the responsible
Federal agency must enter into formal consultation with the Service.
Federal agency actions within the species habitat that may require
conference or consultation or both as described in the preceding
paragraph include management and any other landscape altering
activities on Federal lands in suitable wolverine habitat within the
range of the species administered by the Department of Defense, U.S.
Fish and Wildlife Service, Bureau of Land Management, National Park
Service, and U.S. Forest Service; construction and management of gas
pipeline and power line rights-of-way in suitable wolverine habitat by
the Federal Energy Regulatory Commission; construction and maintenance
of roads or highways by the Federal Highway Administration in suitable
wolverine habitat; and permitting of infrastructure development in
suitable wolverine habitat for recreation, oil and gas development, or
residential development by the U.S. Forest Service, National Park
Service, Bureau of Land Management, U.S. Fish and Wildlife Service, or
Department of Defense.
The Act and its implementing regulations set forth a series of
general prohibitions and exceptions that apply to all endangered
wildlife. The prohibitions of section 9(a)(2) of the Act, codified at
50 CFR 17.21 for endangered wildlife, in part, make it illegal for any
person subject to the jurisdiction of the United States to take
(includes harass, harm, pursue, hunt, shoot, wound, kill, trap,
capture, or collect; or to attempt any of these), import, export, ship
in interstate commerce in the course of commercial activity, or sell or
offer for sale in interstate or foreign commerce any listed species.
Under the Lacey Act (18 U.S.C. 42-43; 16 U.S.C. 3371-3378), it is also
illegal to possess, sell, deliver, carry, transport, or ship any such
wildlife that has been taken illegally. Certain exceptions apply to
agents of the Service and State conservation agencies.
We may issue permits to carry out otherwise prohibited activities
involving endangered and threatened wildlife species under certain
circumstances. Regulations governing permits are codified at 50 CFR
17.22 for endangered species, and at 17.32 for threatened species. With
regard to endangered wildlife, a permit must be issued for the
following purposes: for scientific purposes, to enhance the propagation
or survival of the species, and for incidental take in connection with
otherwise lawful activities.
It is our policy, as published in the Federal Register on July 1,
1994 (59 FR 34272), to identify to the maximum extent practicable at
the time a species is listed, those activities that would or would not
constitute a violation of section 9 of the Act. The intent of this
policy is to increase public awareness of the effect of a proposed
listing on proposed and ongoing activities within the range of species
proposed for listing. The following activities could potentially result
in a violation of section 9 of the Act; this list is not comprehensive:
Unauthorized collecting, handling, possessing, selling, delivering,
carrying, or transporting of the species, including import or export
across State lines and international boundaries, except for properly
documented antique specimens of these taxa at least 100 years old, as
defined by section 10(h)(1) of the Act.
Questions regarding whether specific activities would constitute a
violation of section 9 of the Act should be directed to the Montana
Ecological Services Field Office (see FOR FURTHER INFORMATION CONTACT).
Requests for copies of the regulations concerning listed animals and
general inquiries regarding prohibitions and permits may be addressed
to the U.S. Fish and Wildlife Service, Endangered Species Permits, 134
Union Boulevard, Suite 650, Lakewood, CO 80228; Telephone 303-236-4265.
A determination to list the contiguous United States DPS of the
North American wolverine as a threatened species under the Act, if we
ultimately determine that listing is warranted, will not regulate
greenhouse gas emissions. Rather, it will reflect a determination that
the DPS meets the definition of a threatened species under the Act,
thereby establishing certain protections for them under the ESA. While
we acknowledge that listing will not have a direct impact on the loss
of deep, persistent, late spring snowpack or the reduction of
greenhouse gases, we expect that it will indirectly enhance national
and international cooperation and coordination of conservation efforts,
enhance research programs, and encourage the development of mitigation
measures that could help slow habitat loss and population declines. In
addition, the development of a recovery plan will guide efforts
intended to ensure the long-term
[[Page 7888]]
survival and eventual recovery of the lower 48 states DPS of the
wolverine.
Special Rule Under Section 4(d) of the Act
Whenever a species is listed as a threatened species under the Act,
the Secretary may specify regulations that he deems necessary and
advisable to provide for the conservation of that species under the
authorization of section 4(d) of the Act. These rules, commonly
referred to as ``special rules,'' are found in part 17 of title 50 of
the Code of Federal Regulations (CFR) in Sec. Sec. 17.40-17.48. This
special rule for Sec. 17.40 would prohibit take of any wolverine in
the contiguous United States when associated with or related to
trapping, hunting, shooting, collection, capturing, pursuing, wounding,
killing, and trade. In this context, any activity where wolverines are
attempted to be, or are intended to be, trapped, hunted, shot,
captured, or collected, in the contiguous United States, will be
prohibited. It will also be prohibited to incidentally trap, hunt,
shoot, capture, pursue, or collect wolverines in the course of
otherwise legal activities. All otherwise legal activities involving
wolverines and their habitat that are conducted in accordance with
applicable State, Federal, tribal, and local laws and regulations are
not considered to be take under this regulation. This includes
activities that occur in and may modify wolverine habitat such as those
described below.
In this proposed listing rule, we identified several risk factors
for the wolverine DPS that, in concert with climate change, may result
in reduced habitat value for the species. These risk factors include
human activities like dispersed recreation, land management activities
by Federal agencies and private landowners, and infrastructure
development. However, the scale at which these activities occur is
relatively small compared to the average size of wolverine's home
range, between 300 and 500 km\2\ (186 and 310 mi\2\). For example, ski
resorts constitute the largest developments in wolverine habitats. In
Colorado, the state with the most ski resorts in the range of the
wolverine, ski resort developments cover only 0.6 percent of available
wolverine habitat (Colorado Division of Wildlife 2010, p. 16). Other
developments are more localized still, such as mines and small
infrastructure. It is possible that these forms of habitat alteration
may affect individual wolverines, by causing the temporary movement of
a few individuals within or outside of their home ranges during or
shortly after construction. However, due to the small scale of the
habitat alteration involved in these sorts of activities, we conclude
that the overall impact of these activities is not significant to the
conservation of the species. Dispersed recreation like snowmobiling and
back country skiing, and warm season activities like backpacking and
hunting, occur over larger scales; however, there is little evidence to
suggest that these activities may affect wolverines significantly or
have a significant effect on conservation of the DPS. Preliminary
evidence suggests that wolverines can coexist amid high levels of
dispersed motorized and nonmotorized use (Heinenmeyer et al. 2012,
entire), possibly shifting activity to avoid the most heavily used
areas within their home ranges.
Transportation corridors and urban development in valley bottoms
between patches of wolverine habitat may inhibit individual wolverines'
movement between habitat patches; however, wolverines have made several
long-distance movements in the recent past that indicates they are able
to navigate current landscapes as they search for new home ranges. As
described above, we have no evidence to suggest that current levels of
transportation infrastructure development or residential development
are a threat to the DPS or will become one in the future.
Land management activities (principally timber harvest, wildland
firefighting, prescribed fire, and silviculture) can modify wolverine
habitat, but this generalist species appears to be little affected by
changes to the vegetative characteristics of its habitat. In addition,
most wolverine habitat occurs at high elevations in rugged terrain that
is not conducive to intensive forms of silviculture and timber harvest.
Therefore, we anticipate that habitat modifications resulting from
these types of land management activities would not significantly
affect the conservation of the DPS, as we described above.
The proposed special rule under section 4(d) of the Act will
provide for the possession and take of wolverines that are (1) legally
held at the time of listing (2) legally imported pursuant to applicable
Federal and state statutes, or (3) captively bred without a permit. The
special rule will also allow the continuation of the export of captive-
bred wolverines provided applicable Federal and state laws are
followed, and provide for the transportation of wolverine skins in
commerce within the United States. The export skins from wolverines
documented as captive-bred will be permitted. Legally possessed skins
may be transported in interstate trade without permits.
In this proposed rule, we include a prohibition against incidental
take of wolverine in the course of legal trapping activities directed
at other species. However, documented take of wolverine from incidental
trapping has been low. 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). In Idaho, the U.S. Department of Agriculture 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. We are requesting the
public, Federal agencies, and the affected State fish and wildlife
agencies to submit public comments on this issue, including any State
management plans related to trapping regulations and any measures
within those plans that may avoid or minimize the risk of wolverine
mortality from incidental trapping for other species.
Critical Habitat
Section 3(5)(A) of the Act defines critical habitat as ``(i) the
specific areas within the geographical area occupied by the species, at
the time it is listed * * * on which are found those physical or
biological features (I) Essential to the conservation of the species
and (II) which may require special management considerations or
protection; and (ii) specific areas outside the geographical area
occupied by the species at the time it is listed * * * upon a
determination by the Secretaries of Commerce and Interior that such
areas are essential for the conservation of the species.'' Section 3(3)
of the Act (16 U.S.C. 1532(3)) also defines the terms ``conserve,''
``conserving,'' and ``conservation'' to mean ``to use and the use of
all methods and procedures which are necessary to bring any endangered
species or threatened species to the point at which the measures
provided pursuant to this chapter are no longer necessary.''
Section 4(a)(3) of the Act and implementing regulations (50 CFR
424.12) require that, to the maximum extent prudent and determinable,
we designate critical habitat at the time a species is determined to be
an endangered or threatened species. Critical habitat may only be
designated within the jurisdiction of the United States, and may not be
designated for jurisdictions outside of the United States (50 CFR
424(h)). Our regulations
[[Page 7889]]
(50 CFR 424.12(a)(1)) state that designation of critical habitat is not
prudent when one or both of the following situations exist: (1) The
species is threatened by taking or other activity and the
identification of critical habitat can be expected to increase the
degree of threat to the species; or (2) such designation of critical
habitat would not be beneficial to the species. Our regulations (50 CFR
424.12(a)(2)) further state that critical habitat is not determinable
when one or both of the following situations exists: (1) Information
sufficient to perform required analysis of the impacts of the
designation is lacking; or (2) the biological needs of the species are
not sufficiently well known to permit identification of an area as
critical habitat.
Delineation of critical habitat requires, within the geographical
area occupied by the DPS of the North American wolverine in the
contiguous United States, identification of the physical and biological
features essential to the conservation of the species. In general
terms, physical and biological features essential to the wolverine may
include (1) Areas defined by persistent spring snowpack and (2) areas
with avalanche debris (bottom of avalanche chutes where large trees,
rocks, and other debris are swept) and talus slopes or boulder fields
(debris piles of large rocks, trees, and branches) in which females can
construct dens which provide security from large predators and buffer
against wind and low temperatures.
Information regarding the wolverine's life functions and habitats
associated with these functions has expanded greatly in recent years.
We need additional time to assess the potential impact of a critical
habitat designation, including whether there will be any benefit to
wolverine from such a designation. A careful assessment of the habitats
that may qualify for designation as critical habitat will require a
thorough assessment in light of projected climate change and other
threats. At this time, we also need more time to analyze the
comprehensive data to identify specific areas appropriate for critical
habitat designation. Accordingly, we find designation of critical
habitat to be ``not determinable'' at this time.
Peer Review
In accordance with our joint policy on peer review published in the
Federal Register on July 1, 1994 (59 FR 34270), we will seek the expert
opinions of at least three appropriate and independent specialists
regarding this proposed rule. The purpose of peer review is to ensure
that our listing determination and critical habitat designation are
based on scientifically sound data, assumptions, and analyses. We have
invited these peer reviewers to comment during this public comment
period.
We will consider all comments and information received during this
comment period on this proposed rule during our preparation of a final
determination. Accordingly, the final decision may differ from this
proposal.
Required Determinations
Clarity of the Rule
Executive Order 12866 requires each agency to write regulations
that are easy to understand. We invite your comments on how to make
this rule easier to understand including answers to questions such as
the following: (1) Are the requirements in the rule clearly stated? (2)
Does the rule contain technical language or jargon that interferes with
its clarity? (3) Does the format of the rule (grouping and order of
sections, use of headings, paragraphing, etc.) aid or reduce its
clarity? (4) Would the rule be easier to understand if it were divided
into more (but shorter) sections? (5) Is the description of the rule in
the SUPPLEMENTARY INFORMATION section of the preamble helpful in
understanding the rule? What else could we do to make the rule easier
to understand?
Send a copy of any comments that concern how we could make this
rule easier to understand to Office of Regulatory Affairs, Department
of the Interior, Room 7229, 1849 C Street NW., Washington, DC 20240.
You also may email the comments to this address: Exsec@ios.goi.gov.
Paperwork Reduction Act of 1995 (44 U.S.C. 3501, et seq.)
This rule does not contain any new collections of information that
require approval by Office of Management and Budget (OMB) under the
Paperwork Reduction Act. This rule will not impose recordkeeping or
reporting requirements on State or local governments, individuals,
businesses, or organizations. An agency may not conduct or sponsor, and
a person is not required to respond to, a collection of information
unless it displays a currently valid OMB control number.
National Environmental Policy Act (42 U.S.C. 4321 et seq.)
We have determined that environmental assessments and environmental
impact statements, as defined under the authority of the National
Environmental Policy Act of 1969, need not be prepared in connection
with listing a species as an endangered or threatened species under the
Endangered Species Act. We published a notice outlining our reasons for
this determination in the Federal Register on October 25, 1983 (48 FR
49244).
References Cited
A complete list of all references cited in this proposed rule is
available on the Internet at http://www.regulations.gov or upon request
from the Field Supervisor, Montana Ecological Services Field Office
(see FOR FURTHER INFORMATION CONTACT section).
Authors
The primary authors of this proposed rule are the staff members of
the Montana Ecological Services Field Office (see FOR FURTHER
INFORMATION CONTACT).
List of Subjects in 50 CFR Part 17
Endangered and threatened species, Exports, Imports, Reporting and
recordkeeping requirements, and Transportation.
Proposed Regulation Promulgation
Accordingly, we propose to amend part 17, subchapter B of chapter
I, title 50 of the Code of Federal Regulations, as set forth below:
PART 17--[AMENDED]
0
1. The authority citation for part 17 continues to read as follows:
Authority: 16 U.S.C. 1361-1407; 1531-1544; and 4201-4245, unless
otherwise noted.
0
2. In Sec. 17.11(h) add entries for ``Wolverine, North American'' to
the List of Endangered and Threatened Wildlife in alphabetical order
under Mammals to read as set forth below:
Sec. 17.11 Endangered and threatened wildlife.
* * * * *
(h) * * *
[[Page 7890]]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Species Vertebrate
-------------------------------------------------------- population where Critical Special
Historic range endangered or Status When listed habitat rules
Common name Scientific name threatened
--------------------------------------------------------------------------------------------------------------------------------------------------------
Mammals
* * * * * * *
Wolverine, North American........ Gulo gulo luscus.... U.S.A. (Alaska and Where found within T ........... NA 17.40(a)
northern contiguous U.S.A.,
contiguous except where
States); Canada. listed as an
experimental
population.
Wolverine, North American........ Gulo gulo luscus.... U.S.A. (Alaska and U.S.A. (specified XN ........... NA 17.84(d)
northern portions of CO,
contiguous NM, and WY; see
States); Canada. 17.84(d)).
* * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
0
3. Amend Sec. 17.40 by revising paragraph (a) to read as follows:
Sec. 17.40 Special rules--mammals.
(a) Wolverine, North American (Gulo gulo luscus).
(1) Which populations of the North American wolverine are covered
by this special rule? This rule covers the distribution of this species
in the contiguous United States.
(2) What activities are prohibited? Any activity where wolverines
are attempted to be, or are intended to be, trapped, hunted, shot,
captured, or collected, in the contiguous United States, will be
prohibited. It will also be prohibited to incidentally trap, hunt,
shoot, capture, pursue, or collect wolverines in the course of
otherwise legal activities.
(3) What activities are allowed? Incidental take of wolverines will
not be a violation of section 9 of the Act, if it occurs from any other
otherwise legal activities involving wolverines and their habitat that
are conducted in accordance with applicable State, Federal, tribal, and
local laws and regulations. Such activities occurring in wolverine
habitat include:
(i) Dispersed recreation such as snowmobiling, skiing, backpacking,
and hunting for other species;
(ii) Management activities by Federal agencies and private
landowners such as timber harvest, wildland firefighting, prescribed
fire, and silviculture;
(iii) Transportation corridor and urban development;
(iv) Mining;
(v) Transportation and trade of legally possessed wolverine skins
and skins from captive-bred wolverines within the United States.
* * * * *
Dated: January 16, 2013.
Rowan W. Gould,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. 2013-01478 Filed 2-1-13; 8:45 am]
BILLING CODE 4310-55-P