[Federal Register Volume 76, Number 126 (Thursday, June 30, 2011)]
[Proposed Rules]
[Pages 38504-38532]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-16349]
[[Page 38503]]
Vol. 76
Thursday,
No. 126
June 30, 2011
Part III
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; 12-Month Finding on a
Petition To List a Distinct Population Segment of the Fisher in Its
United States Northern Rocky Mountain Range as Endangered or Threatened
With Critical Habitat; Proposed Rule
Federal Register / Vol. 76 , No. 126 / Thursday, June 30, 2011 /
Proposed Rules
[[Page 38504]]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R6-ES-2010-0017; MO 92210-0-0008]
Endangered and Threatened Wildlife and Plants; 12-Month Finding
on a Petition To List a Distinct Population Segment of the Fisher in
Its United States Northern Rocky Mountain Range as Endangered or
Threatened With Critical Habitat
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Notice of 12-month petition finding.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a
12-month finding on a petition to list a distinct population segment
(DPS) of the fisher (Martes pennanti) in its U.S. Northern Rocky
Mountain range, including portions of Montana, Idaho, and Wyoming, as
endangered or threatened and designate critical habitat under the
Endangered Species Act of 1973, as amended (Act). After review of all
available scientific and commercial information, we find that listing
the fisher in the U.S. Northern Rocky Mountains as threatened or
endangered is not warranted at this time.
DATES: The finding announced in this document was made on June 30,
2011.
ADDRESSES: This finding is available on the Internet at http://www.regulations.gov at Docket Number FWS-R6-ES-2010-0017. Supporting
documentation we used in preparing this finding is available for public
inspection, by appointment, during normal business hours at the U.S.
Fish and Wildlife Service, Montana Field Office, 585 Shepard Way,
Helena, MT 59601; telephone (406) 449-5225. We ask the public to submit
any new information that becomes available concerning the status of, or
threats to, the fisher, in addition to new information, materials,
comments, or questions concerning this finding, to the above address.
No information will be accepted by facsimile. The petition finding,
related Federal Register notices, and other pertinent information, may
be obtained online at http://www.fws.gov/mountain-prairie/species/mammals/fisher/.
FOR FURTHER INFORMATION CONTACT: Mark Wilson, Field Supervisor, Montana
Ecological Services Field Office (see ADDRESSES); or by telephone at
(406) 449-5225. If you use a telecommunications device for the deaf
(TDD), call the Federal Information Relay Service (FIRS) at (800) 877-
8339.
SUPPLEMENTARY INFORMATION:
Background
Section 4(b)(3)(B) of the Act (16 U.S.C. 1531 et seq.) requires
that, for any petition to revise the Federal Lists of Endangered and
Threatened Wildlife and Plants that contains substantial scientific and
commercial information that listing may be warranted, we make a finding
within 12 months of the date of our receipt of the petition. In this
finding, we will determine that the petitioned action is: (a) Not
warranted, (b) warranted, or (c) warranted, but the immediate proposal
of a regulation implementing the petitioned action is precluded by
other pending proposals to determine whether species are threatened or
endangered, and expeditious progress is being made to add or remove
qualified species from the Federal Lists of Endangered and Threatened
Wildlife and Plants. Section 4(b)(3)(C) of the Act requires that we
treat a petition for which the requested action is found to be
warranted but precluded as though resubmitted on the date of such
finding, requiring a subsequent finding be made within 12 months. We
must publish these 12-month findings in the Federal Register.
Previous Federal Actions
U.S. Northern Rocky Mountains
On March 6, 2009, we received a petition dated February 24, 2009,
from the Defenders of Wildlife, Center for Biological Diversity,
Friends of the Bitterroot, and Friends of the Clearwater (petitioners)
requesting that the fisher in the Northern Rocky Mountains of the
United States (USNRMs) be considered a DPS and listed as endangered or
threatened, and critical habitat be designated under the Act (Defenders
of Wildlife et al. 2009, entire). In an April 9, 2009, letter to the
petitioners, we responded that we had reviewed the information
presented in the petition and determined that issuing an emergency
regulation temporarily listing the species under section 4(b)(7) of the
Act was not warranted (Guertin 2009, entire). We informed the
petitioners that due to staffing and funding constraints in Fiscal Year
2009, we would not be able to further address the petition at that
time, but would complete the action when resources allowed. We
published a 90-day finding on April 16, 2010, stating that the petition
presented substantial information that listing a DPS of fisher in the
USNRMs may be warranted, and initiated a status review of the species
(75 FR 19925). The notice of a 90-day finding and commencement of a 12-
month status review for the USNRMs DPS was published in the annual
Candidate Notice of Review on November 10, 2010 (75 FR 69222).
Fishers in the USNRMs were previously petitioned for listing with a
U.S. Pacific States' population in 1994 (see below).
U.S. Pacific States
On June 5, 1990, we received a petition dated May 29, 1990, from
Mr. Eric Beckwitt, Forest Issues Task Force, Sierra Biodiversity
Project, and others requesting that the Pacific fisher (Martes pennanti
pacifica) be listed as an endangered species in California, Oregon, and
Washington under the Act. On January 11, 1991, we published a 90-day
finding (56 FR 1159) indicating that the fisher in the Pacific States
is a distinct population that is geographically isolated from
populations in the Rocky Mountains and British Columbia and represents
a listable entity under the Act. The finding also indicated that the
petition had not presented substantial information indicating that a
listing may be warranted because of a lack of information on fisher
habitat needs, population size and trends, and demographic parameters
(56 FR 1159).
On December 29, 1994, we received a petition dated December 22,
1994, from the Biodiversity Legal Foundation requesting that two fisher
populations in the western United States, including the States of
Washington, Oregon, California, Idaho, Montana, and Wyoming, be listed
as threatened under the Act. Based on our review, we found that the
petition did not present substantial information indicating that
listing the two western United States fisher populations as a DPS was
warranted (61 FR 8016, March 1, 1996). The best available scientific
evidence at that time indicated that the range of the fisher was
contiguous across Canada with some areas having abundant populations,
and through southward peninsular extensions, was contiguous with the
U.S. Rocky Mountain and Pacific populations (61 FR 8016). No evidence
was presented in the petition to support physical, physiological,
ecological, or behavioral separations (61 FR 8016).
On December 5, 2000, we received a petition dated November 28,
2000, from 12 organizations, with the lead organizations identified as
the Center for Biological Diversity and the Sierra Nevada Forest
Protection Campaign, requesting that the West Coast DPS of
[[Page 38505]]
the fisher, including portions of California, Oregon, and Washington,
be listed as endangered and critical habitat be designated under the
Act. A court order was issued on April 4, 2003, by the U.S. District
Court, Northern District of California, that required the Service to
submit for publication in the Federal Register a 90-day finding on the
2000 petition (Center for Biological Diversity, et al. v. Norton et
al., No. C 01--2950 SC). On July 10, 2003, we published a 90-day
petition finding that the petition provided substantial information
that listing may be warranted and initiated a 12-month status review
(68 FR 41169).
On April 8, 2004, we published a warranted 12-month finding for
listing of the fisher's West Coast DPS (69 FR 18770). A listing action
was precluded by higher priorities and the West Coast DPS was added to
our candidate species list. On April 8, 2010, the Center for Biological
Diversity, Sierra Forest Legacy, Environmental Protection Information
Center, and Klamath-Siskiyou Wildlands Center filed a complaint in the
United States District Court for the Northern District of California
seeking an order for the Service to withdraw the 2004 warranted-but-
precluded finding and proceed with a proposed rule to list the species
under the Act (Center for Biological Diversity, et al. v. Salazar, et
al., No. CV 10--1501). A resolution of the complaint is pending.
The West Coast fisher was included in the Service's candidate
notices of review in 2005, 2006, 2007, 2008, 2009, and 2010 (70 FR
24870, May 11, 2005; 71 FR 53756, September 12, 2006; 72 FR 69034,
December 6, 2007; 73 FR 75176, December 10, 2008; 74 FR 57804, November
9, 2009; 75 FR 69222, November 10, 2010).
Species Information
This ``Species Information'' section concentrates on general
biology and fisher studies conducted in the USNRMs area. Additional
information regarding fisher biology in the western portion of its
range can be found in the Service's 12-month finding on a petition to
list the West Coast DPS of the fisher (69 FR 18770).
Description
The fisher is a forest-dwelling, medium-sized mammal, light brown
to dark blackish-brown in color, with the face, neck, and shoulders
sometimes being slightly gray (Powell 1981, p. 1). The chest and
underside often have irregular white patches. The fisher has a long
body with short legs and a long bushy tail. Males range in length from
90 to 120 centimeters (cm) (35 to 47 inches (in.)), and females range
from 75 to 95 cm (29 to 37 in.) in length. At 3.5 to 5.5 kilograms (kg)
(7.7 to 12.1 pounds (lbs)), male fishers weigh about twice as much as
females (2.0 to 2.5 kg (4.4 to 5.5 lbs)) (Powell et al. 2003, p. 638).
Heavier males have been reported across the range, including
individuals within the USNRMs (Sauder 2010 unpublished data; Schwartz
2010 unpublished data); an exceptional specimen from Maine weighed 9 kg
(20.1 lbs) (Blanchard 1964, pp. 487-488). Fishers may show variation in
typical body weight regionally, corresponding with latitudinal
gradients. For example, fishers in the more southern latitudes of the
U.S. Pacific States may weigh less than fishers in the eastern United
States and Canada (Seglund 1995, p. 21; Dark 1997, p. 61; Aubry and
Lewis 2003, p. 87; Lofroth et al. 2010, p. 10).
Taxonomy
The ``Fisher of Pennant,'' or Mustela pennantii, was formally
described by Erxleben in 1777, based on accounts of the same specimen
from either the eastern United States or eastern Canada, by Buffon in
1765 and the naturalist Thomas Pennant in 1771 (Rhoads 1898 as cited in
Goldman 1935, p. 177; Powell 1981, p. 1). Taxonomic stability was not
attained until 80 years after Buffon's original description, when
taxonomists transferred the fisher to the genus Martes and changed the
spelling of the species to pennanti (Hagmeier 1959, p. 185; Powell
1981, p. 1; Powell 1993, pp. 11-12).
The fisher is classified in the order Carnivora, family Mustelidae,
a family that also includes weasels, mink, martens, and otters
(Anderson 1994, p. 14). It is the largest member of the genus Martes,
classified as subgenus Pekania, and occurs only in North America
(Anderson 1994, pp. 22-23). Its geographic range overlaps extensively
with that of the American marten (Martes americana--subgenus Martes),
the only other Martes species in North America (Gibilisco 1994, p. 59).
Characteristic of the subgenus Pekania is large body size compared with
other Martes and the presence of an external median rootlet on the
upper carnassial (fourth) premolar (Anderson 1994, p. 21).
Goldman (1935, p. 177) recognized three subspecies of fisher based
on differences in skull dimensions, although he stated they were
difficult to distinguish: (1) Martes pennanti pennanti in the east and
central regions; (2) M. p. columbiana in the central and northwestern
regions that include the USNRMs; and (3) M. p. pacifica in the western
coast States of the United States. A subsequent analysis questioned
whether there is a sufficient basis to support recognition of different
subspecies based on numerous factors, including the small number of
samples available for examination (Hagmeier 1959, p. 193). Regional
variation in characteristics used by Goldman to discriminate subspecies
appears to be clinal (varying along a geographic gradient), and the use
of clinal variations is ``exceedingly difficult to categorize
subspecies'' (Hagmeier 1959, pp. 192-193). Although subspecies taxonomy
as described by Goldman (1935, p. 177) is often used in literature to
describe or reference fisher populations in different regions of its
range, and recent consideration of genetic variation indicates patterns
of population subdivision similar to the earlier described subspecies
(Kyle et al. 2001, p. 2345; Drew et al. 2003, p. 59), it is not clear
whether Goldman's designations of subspecies are taxonomically valid.
Therefore, for the purposes of this finding, we are evaluating the
fisher in the USNRMs as a DPS of a full species (i.e., M. pennanti).
Biology
Fishers are opportunistic predators, primarily of snowshoe hares
(Lepus americanus), squirrels (Tamiasciurus, Sciurus, Glaucomys, and
Tamias spp.), mice (Microtus, Clethrionomys, and Peromyscus spp.), and
birds (numerous spp.) (reviewed in Powell 1993, pp. 18, 102). Carrion
and plant material (e.g., berries) also are consumed (Powell 1993, p.
18). The fisher is one of the few predators that successfully kills
porcupines (Erethizon dorsatum), and porcupine remains have been found
more often in the gastrointestinal tract and scat of fisher than in any
other predator (Powell 1993, p. 135). There is only one study reporting
the food habits of an established fisher population in the USNRMs, and
that study confirms that snowshoe hares, voles (Microtus and
Clethrionomys spp.), and red squirrels (Tamiasciurus hudsonicus) are
similarly important prey in north-central Idaho as they are in other
parts of the range (Jones 1991, p. 87). Fishers from Minnesota
relocated to the Cabinet Mountains of Montana subsisted primarily on
snowshoe hare and deer (Odocoileus spp.) carrion (Roy 1991, p. 29). As
dietary generalists, fishers across their range tend to forage in areas
where prey is both abundant and vulnerable to capture (Powell 1993, p.
100). Fishers in north-central Idaho exhibit seasonal shifts in habitat
use to forests with younger successional structure plausibly linked to
a concurrent
[[Page 38506]]
seasonal shift in habitat use by their prey species (Jones and Garton
1994, p. 383).
Fishers are estimated to live up to 10 years (Arthur et al. 1992,
p. 404; Powell et al. 2003, p. 644). Both sexes reach maturity their
first year but may not be effective breeders until 2 years of age
(Powell et al. 2003, p. 638). Fishers are solitary except during the
breeding season, which is generally from late February to the middle of
May (Wright and Coulter 1967, p. 77; Frost et al. 1997, p. 607). The
breeding period in north-western Montana and north-central Idaho is
approximately late February through April based on observations of
significant changes of fisher movement patterns and examination of the
reproductive tracts of harvested specimens (Weckwerth and Wright 1968,
p. 980; Jones 1991, pp. 78-79; Roy 1991, pp. 38-39). Uterine
implantation of embryos occurs 10 months after copulation; active
gestation is estimated to be between 30 and 60 days; and birth occurs
nearly 1 year after copulation (Wright and Coulter 1967, pp. 74, 76;
Frost et al. 1997, p. 609; Powell et al. 2003, p. 639).
Litter sizes for fishers range from one to six, with a mean of two
to three kits (Powell et al. 2003, pp. 639-640). Potential litter sizes
in the USNRMs are between two to three per female, based on the
frequency of embryos recovered from harvested females (Weckwerth and
Wright 1968, p. 980; Jones 1991, p. 84). Newborn kits are entirely
dependent and may nurse for 10 weeks or more after birth (Powell 1993,
p. 67). Kits develop their own home ranges by 1 year of age (Powell et
al. 2003, p. 640). Populations of fisher fluctuate in size, and
reproductive rates may vary widely from year to year in response to the
availability of prey (Powell and Zielinski 1994, p. 43).
An animal's home range is the area traversed by the individual in
its normal activities of food gathering, mating, and caring for young
(Burt 1943, p. 351). Only general comparisons of fishers' home range
sizes can be made, because studies across the range have been conducted
by different methods. Generally, fishers have large home ranges, male
home ranges are larger than females, and fisher home ranges in British
Columbia and the USNRMs are larger than those in other areas in the
range of the taxon (reviewed in Powell and Zielinski 1994, p. 58;
reviewed in Lofroth et al. 2010, pp. 67-70). Fisher home ranges vary in
size across North America and range from 16 to 122 square kilometers
(km\2\) (4.7 to 36 square miles (mi\2\)) for males, and from 4 to 53
km\2\ (1.2 to 15.5 mi\2\) for females (reviewed by Powell and Zielinski
1994, p. 58; Lewis and Stinson 1998, pp. 7-8; Zielinski et al. 2004, p.
652). In north-central Idaho, the movements of a small number of radio-
collared fishers indicated that males range from approximately 30 to
120 km\2\ (8.7 to 35 mi\2\) year round, and females range from 6 to 75
km\2\ (1.7 to 22 mi\2\), with a slight reduction in summer (Jones 1991,
pp. 82-83). Fishers in Idaho have home ranges larger than any other
home ranges reported within the range of the taxon (Idaho Office of
Species Conservation (IOSC) 2010, p. 4).
The abundance or availability of vulnerable prey may play a role in
home range selection (Powell 1993, p. 173; Powell and Zielinski 1994,
p. 57). Fishers exhibit territoriality, with little overlap between
members of the same sex; in contrast, overlap between opposite sexes is
extensive, and size and overlap are possibly related to the density of
prey (Powell and Zielinski 1994, p. 59). Male fishers may extend or
temporarily abandon their territories to take long excursions during
the breeding season from the end of February to April presumably to
increase their opportunities to mate (Arthur 1989a, p. 677; Jones 1991,
pp. 77-78). However, males who maintained their home ranges during the
breeding season were more likely to successfully mate than were
nonresident males encroaching on an established range (Aubry et al.
2004, p. 215).
It is not known how fishers maintain territories; it is possible
that scent marking plays an important role (Leonard 1986, p. 36; Powell
1993, p. 170). Direct aggression between individuals in the wild has
not been observed, although signs of fishers fighting and the capture
of male fishers with scarred pelts have been reported (Douglas and
Strickland 1987, p. 516). Combative behavior has been observed between
older littermates and between adult females in captivity (Powell and
Zielinski 1994, p. 59).
There is little information available regarding the long-distance
movements of fishers, although long-distance movements have been
documented for dispersing juveniles and recently relocated individuals
before they establish a home range. Fishers relocated to novel areas in
Montana's Cabinet Mountains and British Columbia moved up to 163 km
(100 mi) from release sites, crossing large rivers and making 700-m
(2,296-ft) elevation changes (Roy 1991, p. 42; Weir and Harestad 1997,
pp. 257, 259).
Juveniles dispersing from natal areas are capable of moving long
distances and navigating various landscape features such as highways,
rivers, and rural communities to establish their own home range (York
1996, p. 47; Weir and Corbould 2008, p. 44). In Maine and British
Columbia, juveniles dispersed from 0.7 km (0.4 mi) to 107 km (66.4 mi)
from natal areas (York 1996, p. 55; Weir and Corbould 2008, p. 44).
Dispersal characteristics may be influenced by factors such as sex,
availability of unoccupied areas, turnover rates of adults, and habitat
suitability (Arthur et al. 1993, p. 872; York 1996, pp. 48-49; Aubry et
al. 2004, pp. 205-207; Weir and Corbould 2008, pp. 47-48). Long-
distance dispersal by vulnerable, less experienced individuals is made
at a high cost and is not always successful. Fifty-five percent of
transient fishers in a British Columbia study died before establishing
home ranges, and only one in six juveniles successfully established a
home range (Weir and Corbould 2008, p. 44). One dispersing juvenile
female traveled an unusually long distance of 135 km (84 mi) over
rivers and through suboptimal habitats before succumbing to starvation
(Weir and Corbould 2008, p. 44). Individuals traveling longer distances
are subject to greater mortality risk (Weir and Corbould 2008, p. 44),
and very few establish the stability of a home range, which improves
the chance of successful recruitment (Aubry et al. 2004, p. 215).
Habitat
The occurrence of fishers at regional scales is consistently
associated with low- to mid-elevation environments of mesic (moderately
moist), coniferous and mixed conifer and hardwood forests with abundant
physical structure near the ground (reviewed by Hagmeier 1956, entire;
Arthur et al. 1989a, pp. 683-684; Banci 1989, p. v; Aubry and Houston
1992 p. 75; Jones and Garton 1994, pp. 377-378; Powell 1994, p. 354;
Powell et al. 2003, p. 641; Weir and Harestad 2003, p. 74). Fishers
avoid areas with little or no cover (Powell and Zielinski 1994, p. 39;
Buskirk and Powell 1994, p. 286); an abundance of coarse woody debris,
boulders, shrub cover, or subterranean lava tubes sometimes provide
suitable overhead cover in non-forested or otherwise open areas
(Buskirk and Powell, 1994, p. 293; Powell et al. 2003, p. 641). In the
understory, the physical complexity of coarse woody debris such as
downed trees and branches provides a diversity of foraging and resting
locations (Buskirk and Powell 1994, p. 295).
Forest succession is a dynamic continuum that begins with an event
such as wildfire, windthrow (areas of downed trees due to high winds)
or
[[Page 38507]]
timber harvest that removes or alters major components of an
environment. Over time the affected environment experiences a series of
changes or seral stages in vegetation species and structure. In the
absence of disturbance and over many decades to hundreds of years
depending on the forest type, mature or late-seral structure and
species composition may result. Late-seral forests (also known as old-
growth) are generally characterized by more diversity of structure and
function than younger developmental stages. Specific characteristics of
late-seral forests vary by region, forest type, and local conditions.
Fishers are associated more commonly with mature forest cover and late-
seral forests with greater physical complexity than other habitats
(reviewed by Powell and Zielinski 1994, p. 52). Other forest
successional stages may suffice if adequate cover and structure is
provided. For example, extensive, mid-mature, second growth forests are
used by fishers in the Northeast and Midwest United States (Coulter
1966, pp. 59-60; Arthur et al. 1989b, pp. 680-683; Powell 1993, p. 92).
To what extent late successional forests are required to support
fisher may be dependent on scale (Powell et al. 2003, p. 641). Home
ranges may be established based on attributes at a landscape scale,
foraging at a site scale, and resting and denning use based on the
element or structural scale (Powell 1993, p. 89; Buskirk and Powell
1994, p. 284; Weir and Corbould 2008, p. 103). Within areas of low and
mid-elevation forests, the most consistent predictor of fisher
occurrence at larger spatial scales is moderate to high levels of
contiguous canopy cover rather than any particular forest plant
community (Buck 1982, p. 30; Arthur et al. 1989b, pp. 681-682; Powell
1993, p. 88; Jones and Garton 1994, p. 41; Weir and Corbould 2010, p.
408). In north-central Idaho, mature to old-growth mesic forests of
grand and subalpine fir in close proximity to riparian areas are used
extensively (Jones 1991, pp. 90, 113; Jones and Garton 1994, p. 381);
fishers in this study avoided forests with less than 40 percent crown
cover and drier upland sites composed of Abies grandis (grand fir),
Abies lasiocarpa (subalpine fir), Pseudotsuga menziesii (Douglas fir),
and Pinus ponderosa (ponderosa pine) (Jones 1991, p. 90). A preliminary
analysis of habitat associations in the USNRMs indicates that in
summer, fishers select areas with larger diameter trees and landscapes
with a higher proportion of large trees, and avoid dry areas typically
populated by ponderosa pine (Schwartz 2010, unpublished data). Winter
detections of fisher are more likely in drainages with a high amount of
canopy cover, and winter avoidance of dry areas is similar to summer
(Schwartz 2010, unpublished data). Fishers in Idaho include forested
environments of differing configurations in their home range including
roadless areas, industrial forest, and national forests managed for
multiple uses (Albrecht and Heusser 2009, p. 19; IOSC 2010, p. 4).
The physical structure of the forest and prey associated with
forest structures are thought to be critical features that explain
fisher habitat use, rather than specific forest types (Buskirk and
Powell 1994, p. 286), and the composition of individual fisher home
ranges is usually a mosaic of different forested environments and
successional stages (reviewed by Lofroth et al. 2010, p. 94). Further,
fishers are opportunistic predators with a relatively general diet, and
the vulnerability of prey may be more important to the use of an area
for foraging than the abundance of a particular prey species (Powell
and Zielinski 1994, p. 54). In north-central Idaho, fishers expand
their use of young forest stages in winter, likely in response to a
seasonal shift in habitat use by their prey or an increase in prey
vulnerability in these areas (Jones and Garton 1994, p. 383).
Individuals translocated to the Cabinet Mountains of Montana from
Minnesota and Wisconsin exhibit winter habitat use similar to that
reported for fishers in north-central Idaho (Roy 1991, p. 60). Fishers
in north-central Idaho and Montana also select forest riparian areas
and draws or valley bottoms that have a strong association with spruce,
which tend to have dense cover, high densities of snowshoe hare, and a
diversity of other prey types (Powell 1994, p. 354; Jones 1991, pp. 90-
93; Heinemeyer 1993, p. 90).
Fishers are more selective of habitat for resting than they are
about foraging or traveling habitat (Arthur et al. 1989b, p. 686;
Powell and Zielinski 1994, p. 54; Powell 1994, p. 353). Across the
range, fishers select resting sites with characteristics of late
successional forests--higher canopy closure, large-diameter trees,
coarse downed wood, and singular features of large snags, tree
cavities, or deformed trees (Powell and Zielinski 1994, p. 54; Lofroth
et al. 2010, pp. 101-103). Rest sites may be selected for their
insulating or thermoregulatory qualities and their effectiveness at
providing protection from predators (Weir et al. 2004, pp. 193-194).
Resting locations for fishers in north-central Idaho are predominately
in mature forest types (Jones and Garton 1994, p. 383). When fishers
use younger forest types, they will select large-diameter trees or
snags, if present, that are remnants of a previously existing older
forest stage (Jones 1991, p. 92). Because of this selectivity for
mature forest type or structure, resting and denning sites may be more
limiting to fisher distribution than foraging habitats, and should
receive particular consideration in managing habitat for fishers
(Powell and Zielinski 1994, pp. 56-57).
Cavities and branches in trees, snags, stumps, rock piles, and
downed timber are used as resting sites, and cavities in large-diameter
live or dead trees are selected more often for natal and maternal dens
(Powell and Zielinski 1994, pp. 47, 56). Fishers do not appear to
excavate their own natal or maternal dens; therefore, other factors
(i.e., heartwood decay of trees, excavation by woodpeckers, broken
branches, frost or fire scars) are important in creating cavities and
narrow entrance holes (Lofroth et al. 2010, p. 112). The tree species
may vary from region to region based on local influences. In regions
where both hardwood and conifers occur, hardwoods are selected more
often, although they may be a minor component of the area (Lofroth et
al. 2010, p. 115). Den trees tend to be older and larger in diameter
than other available trees in the vicinity (reviewed by Lofroth et al.
2010, pp. 115, 117). Little is known of natal or maternal den use or
selection in the USNRMs. A habitat study conducted in north-central
Idaho found no kits or evidence of denning (Jones 1991, p. 83). A
female introduced into Montana's Cabinet Mountains used a downed hollow
log for a natal den only months after release, and it is likely that
this suboptimal site was selected only because of the female's
unfamiliarity with the area (Roy 1991, p. 56).
Snow conditions and ambient temperatures may affect fisher activity
and habitat use. Fishers in eastern parts of the taxon's range may be
less active during winter and avoid areas where deep, soft snow
inhibits movement (Leonard 1980, pp. 108-109; Raine 1981, p. 74).
Historical and current fisher distributions in California and
Washington are consistent with forested areas that receive low or lower
relative snowfall (Krohn et al. 1997, p. 226; Aubry and Houston 1992,
p. 75). Fishers in Ontario, Canada, moved from low-snow areas to high-
snow areas during population increases, indicating a possible density-
dependent migration to less suitable habitats factored by snow
conditions (Carr et al. 2007, p. 633). These distribution and activity
patterns
[[Page 38508]]
suggest that the presence of fisher and their populations may be
limited by deep snowfall. However, the reaction to snow conditions
appears to be variable across the range, with fishers in some locations
not affected by snow conditions or increasing their activity with fresh
snowfall (Jones 1991, p. 94; Roy 1991, p. 53; Weir and Corbould 2007,
p. 1512). Thus, fishers' reaction to snow may be dependent on a myriad
of factors, including, but not limited to, local freeze-thaw cycles,
the rapidity of crust formation, snow interception by the forest
canopy, and prey availability (Krohn et al. 1997, p. 226; Mote et al.
2005, p. 44; Weir and Corbould 2007, p. 1512).
Historical Distribution Across the Range of the Species
Fishers occur only in North America, appearing in the fossil record
approximately 30,000 years ago in the eastern United States throughout
the Appalachian Mountains, south to Georgia, Alabama, and Arkansas, and
west to Ohio and Missouri (Anderson 1994, p. 18). No fossil evidence of
a fisher range expansion to the north or west exists until the middle
Holocene (4,000 to 8,000 years ago) in southern Wisconsin, and only
within the past 4,000 years is there evidence that fishers inhabited
northwestern North America (Graham and Graham 1994, pp. 46, 58).
Although there is limited fossil evidence available from central
Canada, fishers' expansion westward and northward likely coincided with
glacier retreat and the subsequent development of the boreal spruce
forests (Graham and Graham 1994, p. 58). Fossil remains of early fisher
in the northwest have been found in British Columbia, Washington, and
Oregon, and no fossil remains have been discovered in the USNRMs region
(Graham and Graham 1994, pp. 50-55).
Our present understanding of the historical (before European
settlement) distribution of fishers is based on the accounts of natural
historians of the early 20th century and general assumptions of what
constitutes fisher habitat. The presumed fisher range prior to European
settlement of North America (c. 1600) was throughout the boreal forests
across North America in Canada from approximately 60[deg] north
latitude, extending south into the United States in the Great Lakes
area and along the Appalachian, Rocky, and Pacific Coast Mountains
(Figure 1) (Hagmeier 1956, entire; Hall 1981, pp. 985-987; Powell 1981,
pp. 1-2; Douglas and Strickland 1987, p. 513; Gibilisco 1994, p. 60).
The distribution of fishers has been described by numerous authors,
and the distribution boundaries vary depending on the evidence used for
occurrences. The presumed presence of fishers has been drawn along the
lines of forest distribution, and the species has been consistently
described as an associate of boreal forest in Canada, mixed deciduous-
evergreen forests in eastern North America, and coniferous forest
ecosystems in the west (Lofroth et al. 2010, p. 39). Subsequently,
range maps of historical distribution typically portray large areas of
continuous occurrence, although it is likely that the suitability of
habitat to support fishers within the portrayed range varied over time
and spatial scales, subject to climatic variation, large-scale
disturbances, and other ecological factors (Giblisco 1994, p. 70;
Graham and Graham 1994, pp. 57-58). Fishers do not occur in all
forested habitats today, and evidence would indicate they did not
occupy all forest types in the past (Graham and Graham 1994, p. 58).
Based on the contemporaneous assemblages of fossilized remains, it is
likely that habitat selection by fishers has historically been
influenced by the availability of specific types of prey (Graham and
Graham 1994, p. 58).
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Post-European Settlement Distribution Across the Range of the Species
In the late 1800s and early 1900s, fishers experienced reductions
in range, decreases in population numbers, and local extirpations
attributed to overtrapping, predator control, or habitat destruction in
the United States, including the USNRMs, and to a lesser extent in
Canada (Weckwerth and Wright 1968, p. 977; Brander and Books 1973, p.
53; Douglas and Strickland 1987, p. 512; Powell and Zielinski 1994, p.
39). Since the 1950s, fishers have
[[Page 38510]]
recovered in some of the central (Minnesota, Wisconsin, Michigan) and
eastern (Northeastern States and West Virginia) portions of their
historical range in the United States as a result of trapping closures
and regulations, habitat regrowth, and reintroductions (Brander and
Books 1973, pp. 53-54; Powell 1993, p. 80; Gibilisco 1994, p. 61; Lewis
and Stinson 1998, p. 3; Proulx et al. 2004, pp. 55-57; Kontos and
Bologna 2008, entire). Fishers have not returned to the areas south of
the Great Lakes to the southern Appalachian States (Proulx et al. 2004,
p. 57). The historical, early European settlement, and contemporary
distribution of fishers in the USNRMs is discussed in detail in the
following sections.
Current Distribution Outside of the U.S. Northern Rocky Mountains
Presently, fishers are found in all Canadian provinces and
territories except Newfoundland and Prince Edward Island (Proulx et al.
2004, p. 55) (Figure 1). The fisher range in Quebec, Ontario, and
eastern Manitoba is contiguous with currently occupied areas in New
England, northern Atlantic States, Minnesota, Wisconsin, and the Upper
Peninsula of Michigan in the United States (Proulx et al. 2004, pp. 55-
57). In Saskatchewan and Alberta, fishers are found primarily north of
52 degrees and 54 degrees north latitude, respectively, and form no
known breeding population with the United States (Proulx et al. 2004,
p. 58). In Alberta, trapping data indicate that a rare fisher may occur
to the south of high-density population areas to approximately 32 km
(20 mi) north of the United States border along the Continental Divide
near Waterton Lakes National Park, (Corrigan 2010, pers. comm.; Hale
2010, pers. comm.)--an area contiguous with the USNRMs. However, there
is no indication that there is a population of fisher in southern
Alberta or whether the source of the occasional rare fisher detected
there is the distant fisher population of central Alberta, central
British Columbia, or the USNRMs. Fishers occupy low- to mid-elevation
forested areas throughout British Columbia, but are rare or absent from
the coast and from the southern region for at least 200 km (125 mi) to
the border with the United States (Weir et al. 2003, p. 25; Weir and
Lara Almuedo 2010, p. 36).
After reviewing known distribution records for fishers in 1956,
Hagmeier (p. 156) noted that there were no known records from
southeastern British Columbia, which includes the Rocky Mountains in
the eastern Kootenay Region contiguous with northern Idaho and
northwest Montana. A reintroduction of fishers to the Kootenay Region
of southeast British Columbia, an area just north of the USNRMs, was
attempted in the 1990s (Fontana et al. 1999, entire), but ``the
observed survival rate of translocated adults and the few cases of
confirmed reproduction in the area were not likely sufficient for the
population to expand and become self-sustaining'' (Weir et al. 2003, p.
25). The South Thompson Similkameen area of south-central British
Columbia, bordering north-central Washington, produced 88 legally
harvested fishers between 1928 and 2007, and 13 since 1985 (Lofroth et
al. 2010, p. 48). Because the northern boundary of the South Thompson
Similkameen is considered the southern extent of the fisher population
distribution in the province (Weir and Lara Almuedo 2010, p. 36), the
significance of the trapping data to fisher distribution is not clear
without more specific location information. Harvest data could indicate
that individuals were captured at the periphery of larger, established
populations, that there is a low-density population in south-central
British Columbia, or that individuals represent transient or
extralimital (outside an established population area) records.
In the western United States outside of the USNRMs, fishers occur
in a few disjunct and relatively small areas of their former range in
the Cascade Mountains of southwest Oregon, the Klamath and Coastal
Ranges of southwest Oregon and northwest California, and the Southern
Sierra Nevada Mountains in east-central California (Proulx et al. 2004;
Lofroth et al. 2010, pp. 47-49). A reintroduction program is underway
on the Olympic Peninsula of Washington State, and the program's
objective of establishing a self-sustainable population of fisher has
yet to be achieved (Lewis et al. 2009, p. 3).
Historical Distribution and Early European Settlement Distribution in
the U.S. Northern Rocky Mountains
Presumed historical distribution of fishers in the USNRMs is
depicted as continuous with eastern British Columbia and southwestern
Alberta in Canada, bounded on the east by the forested areas of the
front range of the Rocky Mountains at approximately 113 degrees west
longitude in Montana, the south at approximately 44 degrees north
latitude, and the west in Idaho at approximately 116.5 degrees west
longitude, extending to the northwest, north of the Palouse Prairie in
Idaho to include the forested Pend Oreille River area of northeastern
Washington (Hagmeier 1956, entire; Hall 1981, pp. 985-987; Gibilisco
1994, p. 64) (Figure 1). The described historical distribution also
includes individually isolated areas in the present-day Greater
Yellowstone Ecosystem (northwest Wyoming, southern Montana and east-
central Idaho), and north-central Utah (Gibilisco 1994, p. 64). The
representation of historical fisher distribution in the USNRMs by the
sources above should be viewed cautiously, because it is based on
limited information and records collected in the late 1800s to mid-
1900s (Hagmeier 1956, pp. 154, 156, 161, 163; Hall 1981, p. 985) after
European settlement had influence in the area. In addition, as stated
previously, fishers have been consistently described as associates of
coniferous forest ecosystems in the west, and the presumed historical
presence of fishers was drawn along the lines of forest distribution,
with little physical evidence of whether fishers occupied those
habitats.
Montana
No reliable records are available for Montana, and historical and
early settlement distribution in the western forested areas of the
State was assumed based on the reports of the presence of fishers in
northwest Wyoming and central Idaho (Hagmeier 1956, p. 156). Vinkey
(2003, pp. 44-69) investigated fisher records in the Rocky Mountains,
concentrating on Montana, to determine the fisher distribution post-
settlement and prior to their apparent disappearance in the 1920s
(Newby and McDougal 1964, p. 487; Weckworth and Wright 1968, p. 977).
The first reference to fisher in Montana was a shipping record of pelts
from Fort Benton in 1875 (Vinkey 2003, p. 49). Although shipping
records are not definitive of the product origin, it is likely some of
the fisher pelts were of Montana origin because of Montana's prominence
in the fur trade and Fort Benton's location at the upper reaches of the
Missouri River (Vinkey 2003, p. 49).
Reports of fishers in Montana's Glacier National Park in the early
1900s were dismissed as ``unreliable'' and ``unauthentic'' by Newby
(cited in Hagmeier 1956, p. 156); nevertheless, these records have been
cited by other authors, in addition to reports from early trappers, to
support a distribution of fishers in Montana as far south as Wyoming
(Hoffman et al. 1969, p. 596; Vinkey 2003, p. 50). Hoffman et al.
(1969, p. 596) interpreted the lack of reliable records as an
indication of the fisher's extirpation in Montana and adjacent areas
before any specimens
[[Page 38511]]
could be preserved. Thus, in Montana, the presumed occurrence of
fishers before translocations occurred in 1959 is based on trapper
accounts alone (Weckworth and Wright 1968, p. 977; Hoffman et al. 1969,
p. 596).
Idaho
The historical presence of fisher in Idaho was based on an 1890
specimen from Alturas Lake (originally Sawtooth Lake) in the Sawtooth
Mountains of Blaine County in central Idaho (Goldman 1935, p. 177;
Hagmeier 1956, p. 154; Drew et al. 2003, p. 62; Schwartz 2007, p. 922),
and other 20th century reports of fishers in the ``mountainous parts of
the state,'' including the Selkirk (north), Bitterroot (northeast), and
Salmon River (central) ranges (Hagmeier 1956, p. 154). Only two fisher
specimens document the presence of fishers in the USNRMs prior to their
presumed extirpation in the 1920s (Williams 1963, p. 9). Both specimens
originated in Idaho. The above-mentioned 1890 specimen from Alturas
Lake, Blaine County, in central Idaho is housed in the collection of
the National Museum of Natural History in Washington, DC, and this
specimen has been pivotal for supporting historical distribution and
post-settlement representation, and for suggesting that an indigenous
population has survived since the 1920s in the USNRMs (Hagmeier 1956,
p. 154; Hall 1981, p. 985; Drew et al. 2003, pp. 59, 62; Vinkey et al.
2006, p. 269). An 1896 Harvard Museum specimen collected in Idaho
County in north-central Idaho west of the Bitterroot Divide, which
separates Idaho and Montana, further supports the extent of fisher
distribution in the late 1800s, and supports a close ecological
connection between north-central Idaho and west-central Montana (Vinkey
et al. 2006, p. 269; Schwartz 2007, pp. 923-924).
Wyoming and Utah
The first reported fisher capture in Wyoming is often cited as
occurring in the 1920s from the Beartooth Plateau east of Yellowstone
National Park near the Montana State line (Thomas 1954, p. 28; Hagmeier
1956, p. 163). The pelt of a poached fisher was confiscated in
Yellowstone National Park in the 1890s, but it is not clear where the
animal was captured originally (Skinner 1927, p. 194; Buskirk 1999, p.
169). Fishers have been seldom described in Wyoming (Buskirk 1999, p.
169), and by the 1950s fishers were considered ``extinct or nearly so''
in the Yellowstone area (Thomas 1954, p. 3; Hagmeier 1956, p. 163). As
early as the 1920s the fisher was considered rare or absent from
Yellowstone National Park (Skinner 1927, p. 180). The inclusion of Utah
in the historical range of the fisher was based solely on photographs
of tracks taken in 1938 (Hagmeier 1956, p. 161).
Location of Restocking Efforts in the U.S. Northern Rocky Mountains
By 1930, fishers were thought to be extirpated from the USNRMs in
Montana and Idaho as they were in other parts of the United States
(Williams 1963, p. 9; Newby and McDougal 1964, p. 487; Weckworth and
Wright 1968, p. 977). Montana Department of Fish and Game (now Montana
Fish, Wildlife and Parks (MTFWP)) initiated a restocking program for
fisher in 1959 with 36 individuals from central British Columbia
transplanted to the Purcell, Swan, and Pintler Ranges in northwestern
and west-central Montana (Weckworth and Wright 1968, p. 979). Idaho
Fish and Game (IDFG) followed with a reintroduction program for fishers
in 1962. Forty-two fishers from central British Columbia were
transplanted to areas considered to have been formerly occupied before
presumed extirpation in north-central Idaho, including the Bitterroot
divide area (Williams 1963, p. 9; reviewed by Vinkey 2003, p. 55).
Minnesota and Wisconsin were the sources for 110 fishers transplanted
to the Cabinet Mountains of northwest Montana between 1989 and 1991
(Roy 1991, p. 18; Heinemeyer 1993, p. ii). After an absence of
authenticated records for over 20 years in the USNRMs, areas near
release sites yielded fisher captures in Montana in the years following
the first reintroduction efforts in 1959 (Newby and McDougal 1964, p.
487; Weckworth and Wright 1968, p. 979). No post-release studies were
conducted in Idaho until the mid-1980s, but marten trappers in the
State reported inadvertent captures of fishers by the late 1970s (Jones
1991, p. 1).
Contemporary Distribution in the U.S. Northern Rocky Mountains
The use of unreliable records to support distribution and
population extent has led to overestimation of other species' ranges
(Aubry and Lewis 2003, p. 86; McKelvey et al. 2008, p. 550). Mindful of
that, we have used the most reliable and verified data in this analysis
of the fisher in the USNRMs. We base the contemporary (1960 to present)
record of fisher distribution in the USNRMs on verifiable or documented
records of physical evidence such as legal harvest or incidentally
captured specimens, animals captured for scientific study, genetic
analysis of biological samples, and photographs identified by a
knowledgeable expert. Eyewitness accounts of a fisher itself, or its
sign, by the general public or untrained observer also may be found in
agency databases (IOSC 2010, p. 5-6); however, a correct identification
of fisher or its sign can be difficult by an untrained observer and
these unverified records or anecdotal reports should be viewed
cautiously (Aubry and Lewis 2003, p. 81; Vinkey 2003, p. 59; McKelvey
et al. 2008, p. 551). Other animals that are similar in appearance and
share similar habitats, such as the American marten, mink (Mustela
vison), or domestic cat (Felis catus), may be mistaken for fishers
(Aubry and Lewis 2003, p. 82; Lofroth et al. 2010, p.11; Kays 2011, p.
1). Animal signs, such as tracks, can be significantly altered by
environmental conditions, and fisher tracks can be confused with those
of the more common American marten (Vinkey 2003, p. 59; Giddings 2010,
pers. comm.).
Montana and Idaho
A legal trapping season for fisher was reopened in Montana in 1983
after a series of fisher transplantations and evidence that fishers
were reproducing in the State (Weckwerth and Wright 1968, entire; MTFWP
2010, p. 3). The majority of verified fisher records in the State
through 2009 result from the harvest program (Vinkey 2003, p. 51; MTFWP
2010, p. 2, Attachment 3). In addition, Montana agency files include 48
incidental harvest records between 1968 and 1979 (Vinkey 2003, p. 51).
Prior to 2002, Idaho records included verified fisher presence by
targeted live-trapped and incidental captures, or otherwise-obtained
physical specimens, photographs, and individuals observed directly by
qualified experts (IOSC 2010, p. 7). From 2004 to the present, multiple
State and Federal agencies in Montana and Idaho have partnered to
collect biological data and samples by live-trapping and hair-snares
for genetic testing (Albrecht and Heusser 2010, p. 23; Albrecht 2010,
unpublished data; IOSC 2010, pp. 4-6; MTFWP 2010, p. 2); many surveys
are conducted using a standardized protocol specific to fisher
(Schwartz et al. 2007, entire). Fisher detections (species
identification) and genetic analyses to identify individual fishers
have been provided to us as they become available (Albrecht 2010,
unpublished data); the results of some targeted fisher surveys are
pending (IOSC 2010, p. 10). Harvest specimens and targeted studies
provide confident identification of fishers, but may not represent the
full extent of fisher
[[Page 38512]]
distribution due to biases of trapper effort, site accessibility,
nonrandom site selection to increase the efficacy of detection, or a
lack of either survey or trapping exposure (Vinkey 2003, p. 59;
Schwartz et al. 2007, p. 6; Albrecht and Heusser 2009, p. 19).
In western Montana from 1968 to the late 1980s, fishers were known
to occur in the Bitterroot Mountains bordering north-central Idaho, and
west of the Continental Divide in the Whitefish Range, Flathead, and
Swan Mountain Ranges (Vinkey 2003, p. 53). Trapping or targeted
sampling has not been robust in these areas west of the Continental
Divide since the early 1990s, but there are verified fisher detections
over the past two decades (Vinkey 2003, p. 53; MTFWP 2010, Attachment
2) (Figure 2). Fisher presence has been consistent in the Bitterroot
Mountains to the present, and in the Cabinet Mountains in northwest
Montana since the late 1980s introduction (Vinkey 2003, p. 53; MTFWP
2010, Attachment 2).
Fishers in Idaho are found in the Selkirk Mountains in the north,
the Clearwater and Salmon River Mountains in central Idaho, and the
Bitterroot Range, including the Selway-Bitterroot Wilderness, in the
north-central portion of the State.
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Wyoming and Utah
The contemporary distribution of fisher in Wyoming is unknown. Rare
reports of fisher tracks and harvested specimens are available up until
the 1950s (Thomas 1954, p. 31; Hagemeier 1956, p. 163; Buskirk 1999, p.
169). A photograph of an animal near Yellowstone National Park
described as a fisher was featured in a popular publication in 1995
(Gehman, p. 2), but to date there has been no professional or expert
verification that the photographed animal is indeed a fisher. Carnivore
detection surveys were conducted in the Gallatin National Forest in the
northern Greater Yellowstone Ecosystem between 1997 and 2000, using
camera stations, hair-snares, and snow track transects; the surveyors
reported fisher tracks in snow in the Gallatin and Madison Ranges of
southern Montana (Gehman and Robinson 2000, p. 7). These records are
considered unverified, because the use of sighting and track
measurements alone are dependent on the observer's level of skill, snow
and weather conditions, and ``notoriously unreliable'' (Vinkey 2003, p.
59).
The Wyoming Fish and Game Department (2010, p. IV-2-26) and
Gibilisco (1994, pp. 63-64) report only two verified records, both
prior to 1970, in or near Yellowstone National Park. One specimen was
described from Ucross, Wyoming, in 1965 (Hall 1981, p. 985) over 217 km
(135 mi) east of the Beartooth Plateau and Yellowstone National Park,
but most of that distance is open grassland or sagebrush, which is
unsuitable for fisher. Proulx et al. (2004, p. 59) could not confirm
the presence of fisher in Wyoming in their status review of Martes
distribution. Schwartz et al. (2007, p. 1) acknowledge that Wyoming may
contain fisher, but there is no evidence to confirm that presence.
Recently, fishers are described as ``accidental'' or ``rare'' in
Wyoming with assumed breeding or records of breeding in the northwest
part of the State (Orabona et al. 2009, p. 152; Wyoming Fish and Game
Department 2010, p. IV-2-26). However, the statement of fisher breeding
in Wyoming is unsubstantiated and apparently made in error, (Oakleaf
2010, pers. comm.). The fisher is considered extirpated in Utah
(Biotics Database 2005, pp. 1-2).
Summary of Contemporary Distribution of Fisher in the U.S. Northern
Rocky Mountains
Based on the available verified specimen data, contemporary fisher
distribution in western Montana and Idaho (Figure 2) covers an area
similar to that depicted in the historical distribution synthesized by
Gibilisco in 1994 (p. 64) (Figure 1). The contemporary distribution of
fishers includes forested areas of western Montana and north-central to
northern Idaho, and the boundary is further described in the ``Distinct
Vertebrate Population Segment'' section of the finding. Based on a lack
of verified records or documentation, we cannot conclude that the
fisher is present, or if a breeding population was ever present, in
Wyoming, including the Greater Yellowstone Ecosystem, which includes
parts of south-central Montana, northwest Wyoming, and south-east
Idaho.
Distribution Based on Genetic Characteristics
Recent genetic analyses revealed the presence of a remnant native
population of fishers in the USNRMs that escaped the extirpation
presumed to have occurred early in the 20th century (Vinkey et al. 2006
p. 269; Schwartz 2007, p. 924). Fishers in the USNRMs today reflect a
genetic legacy of this remnant native population, with unique genetic
identity found nowhere else in the range of the fisher and genetic
contributions from fishers introduced from British Columbia and the
Midwest United States. We discuss the genetic differences due to this
the native legacy and its significance to the fisher taxon in the
``Significance'' section of the DPS analysis later in this document.
Individuals with native genes are concentrated in the Bitterroot
Mountains of west-central Montana and north-central Idaho, the St. Joe
and Clearwater Regions, and the Lochsa River corridor in Idaho (Vinkey
2003, p. 76; Vinkey et al. 2006, p. 267; Albrecht 2010, unpublished
data). Individuals in these areas appear to form one population based
on the frequency of gene types (Schwartz 2007, p. 924). The unique
genetic type also has been identified in the only two existing USNRMs
fisher specimens from the 1890s (Schwartz 2007, p. 922). The presence
of this unique variation would indicate that fishers in the USNRMs were
isolated from populations outside the region by distance, small
population number, or both, for some time before the influences that
led to the presumed extirpation in the early 20th century (Vinkey 2003,
p. 82). Today, a genetic identity more commonly found in British
Columbia populations also is present in the Bitterroot Divide area, and
fishers in this region are likely a mix of native and individuals
translocated from British Columbia (Vinkey 2003, p. 76; Vinkey et al.
2006, p. 268; Schwartz 2007, p. 924).
Fishers in northwestern Montana and extreme northern Idaho
represent the geographically distant source populations from Minnesota
and Wisconsin that were introduced into the Cabinet Mountains of
Montana in the late 1980s (Drew et al. 2003, p. 59; Vinkey et al. 2006,
pp. 268-269; Albrecht 2010, unpublished data). British Columbia types
also are found in this region, reflecting offspring of a 1959
introduction from Canada, a remnant native population, or possibly
natural immigration from Canada (Vinkey et al. 2006, p. 270; Schwartz
2007, p. 924).
An assessment of the degree of hybridization between native and
introduced individuals is difficult based on the assessment techniques.
Analysis of genetic identity is conducted on mitochondrial DNA, which
only reflects the genetic contribution of the mother (Forbes and
Alledorf 1991, p. 1346; Vinkey 2003, p. 82). Males could make a greater
contribution to distant populations based on their larger home range
sizes and expanded wanderings during the breeding period (Arthur 1989a,
p. 677; Jones 1991, pp. 7-78), but based on mitochondrial DNA analysis
alone, this contribution would not be detected.
Population Status
Estimates of fisher abundance and vital rates are difficult to
obtain and often based on harvest records, trapper questionnaires, and
tracking information (Douglas and Strickland 1987, p. 522), and recent
information is limited. Habitat modeling and behavioral or other
natural history characteristics (e.g., home range sizes) also are used
to estimate population sizes over a geographic area (Lofroth 2004, pp.
19-20; Lofroth et al. 2010, p. 50). Fisher densities over areas of
suitable habitat have been reported, but there are no total or
comprehensive population sizes for the fisher in the eastern United
States or Canada. In the western range, fisher populations have been
estimated using habitat models and home range sizes. Late winter
populations in British Columbia range from 1,403 to 3,715 individuals
(Lofroth 2004, p. 20). In the Southern Sierra Nevada Mountains, the
fisher population is estimated between 160 to 598 individuals depending
on the methods used, and an estimated 4,616 fishers inhabit the
Southwest Oregon/Northern California area (reviewed by Lofroth et al.
2010, p. 50).
As previously noted, fishers in the USNRMs have increased in number
and distribution since their perceived
[[Page 38515]]
extirpation in the 1920s. However, little is known of the population
numbers, trends, or vital rates of fishers in the USNRMs today.
Preliminary work is ongoing to determine the geographic range of the
species, identify populations with native and introduced genes, and
determine the abundance of individuals in populations using DNA
analyses (Schwartz et al. 2007, pp. 1-2). An evaluation of the
translocation effort in the Cabinet Mountains of northwest Montana
between 2001 and 2003 yielded only 4 live-trapped individuals and 28
track detections over 25 survey weeks, indicating that the population
there is likely small and limited in distribution (Vinkey 2003, p. 33)
(Figure 2). Based on genetic similarities, fishers in the Selkirk
Mountains of northern Idaho, just south of the Canadian border, are
likely associated with the fishers from Minnesota and Wisconsin
introduced to Montana's Cabinet Mountains to the east (Cushman et al.
2008, p. 180). Efforts to detect fisher in the Selkirk Mountains
between 2003 and 2005 using hair-snares for genetic analysis produced
26 samples identified as fisher, although the number of unique
individuals is likely much smaller than the number of samples (Cushman
et al. 2008, p. 180).
A review of historical records and carnivore research in Montana
indicates that the fisher is one of the lowest-density carnivores in
the State (Vinkey 2003, p. 61). What is known of fisher populations
today in Montana is primarily derived from harvest data and winter
furbearer track surveys (MTFWP 2010, p. 2, Attachment 8, pp. 2-3). A
Montana habitat model based on 30 years of fisher presence data (the
majority being harvest data) conservatively estimates that there is
high habitat suitability capable of supporting 216 individuals
concentrated in the Bitterroot Mountains along the Idaho border, the
Swan and Flathead River drainages, and the Whitefish and Cabinet
Mountains just south of the Canada border (MTFWP 2010, Attachment 8,
pp. 2-3; Montana Natural Heritage Program (MTNHP) 2010a, entire; 2010b,
entire).
Most of the recent USNRMs fisher survey effort has targeted the
Coeur d'Alene, St. Joe, Clearwater, and Lochsa areas of northern and
north-central Idaho. In 2006 and 2007, 10 individual fishers were
identified in an area of approximately 8,951 km\2\ (3,456 mi\2\) of
potentially suitable habitat in the St. Joe and Coeur d'Alene areas,
north and south of Interstate 90 in northern Idaho (Albrecht and
Heusser 2009, pp. 6, 8, 15). The St. Joe and Coeur d'Alene projects
were not intended to elucidate fisher presence in the entire area of
potentially suitable habitat, but simply to detect the presence of
fisher; therefore, traps were placed in areas highly likely to support
fisher (Albrecht and Heusser 2009, p. 19). Thirty-four fisher were
identified in a 1,295-km\2\ (500-mi\2\) (one fisher per 38 km\2\ (14.7
mi\2\)) area of the Lochsa River corridor of north-central Idaho during
a targeted live-trap study between 2002 and 2004 (Schwartz 2010,
unpublished data). Thirty individual fishers were captured in the
Clearwater area north of the Lochsa River in north-central Idaho
between 2007 and 2010 (Sauder 2010, unpublished data). Based on genetic
data, it appears that individuals in these areas of north-central Idaho
and fishers in west-central Montana represent a single population
(Schwartz 2007, p. 924) (Figure 2). We have no additional information
on the Lochsa River or Clearwater surveys to determine if these reports
are indicative of comprehensive population numbers. No habitat
suitability or capacity model is available for Idaho.
Evaluation of Listable Entities
Under section 3(16) of the Act, we may consider for listing any
species, including subspecies, of fish, wildlife, or plants, or any DPS
of vertebrate fish or wildlife that interbreeds when mature (16 U.S.C.
1532(16)). Such entities are considered eligible for listing under the
Act (and, therefore, are referred to as listable entities), should we
determine that they meet the definition of an endangered or threatened
species. In this case, the petitioners have requested that the fisher
in the USNRMs be considered as a DPS of a full species for listing as
endangered or threatened under the Act. We concluded in our 90-day
finding on the petition that there is support for a DPS of fisher in
the USNRMs (75 FR 19925), and we analyze this possibility further in
the following section after reviewing the best available information.
Distinct Vertebrate Population Segment
Under the Service's DPS policy (61 FR 4722, February 7, 1996),
three elements are considered in the decision concerning the
establishment and classification of a possible DPS. These are applied
similarly for additions to, or removal from, the Federal List of
Endangered and Threatened Wildlife. These elements include:
(1) The discreteness of a population in relation to the remainder
of the species to which it belongs;
(2) The significance of the population segment to the species to
which it belongs; and
(3) The population segment's conservation status in relation to the
Act's standards for listing, delisting, or reclassification (i.e., is
the population segment endangered or threatened).
In evaluating the distribution of fisher and the geographic extent
of a possible DPS in the USNRMs, we examined information cited in the
petition (Defenders et al. 2009, pp. 11-24), published range maps,
published works that included historical occurrences, unpublished
studies related to fisher distribution, and other data submitted to us
subsequent to the request for information published in the 90-day
finding for fisher (75 FR 19925). Fisher distribution in the USNRMs and
extended area was discussed in detail in the preceding ``Distribution''
section.
Discreteness
Under the DPS policy, a population segment of a vertebrate taxon
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.
(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.
Western Montana and north-central to northern Idaho broadly
encompass the area under consideration for a fisher DPS in the USNRMs.
The population area includes the contemporary (1960s reintroductions to
present) distribution of fisher in the USNRMs and is best circumscribed
by geological features and the distribution of habitat known to support
fisher. The distribution of fishers in the USNRMs is bounded by the
southern Bitterroot Range north of Lemhi Pass in Montana, east and then
north along the Continental Divide including forested areas east of the
Divide to the Rocky Mountain Front, north along the eastern boundary of
Glacier National Park, west along the Boundary Mountains and northern
Whitefish Range in northern Montana, west to the southern Selkirk and
southern Purcell Mountains to the Idaho boundary with Washington, south
along the forested areas of northern Idaho bounded on the west by the
Palouse and Camas Prairie regions, south along the Western Mountains
and North Payette River to the Boise Mountains, northeast along the
Salmon River to the southern
[[Page 38516]]
Bitterroot Range north of Lemhi Pass in Idaho (Figure 2). The northern
geographic extent of the fisher distribution roughly coincides with the
border of the United States and Canada at 49 degrees north latitude.
The fisher distribution in the USNRMs is the southern extent of the
taxon's known range in the Rocky Mountains.
Fishers in the USNRMs are physically or geographically separate
from other fisher populations. The range of the fisher in the West
Coast Range of Washington, Oregon, and California is separated from the
USNRMs by distance, natural physical barriers, including the
nonforested high desert areas of the Great Basin in Nevada and eastern
Oregon and the Okanogan Valley in eastern Washington, major highways,
urban and rural open-canopied areas, and agricultural development (69
FR 18770; Lofroth et al. 2010, p. 47). Occupied areas in the USNRMs are
150 to 200 km (93 to 124 mi) from the closest edge of the West Coast
fisher DPS abutting the unoccupied Okanogan Valley of Washington (69 FR
18770, Lofroth et al. 2010, p. 33). Occupied areas in the USNRMs are
approximately 418 km (300 mi) from the closest occupied area of the
West Coast DPS in the southern Cascade Mountains of southwest Oregon or
the Olympic Peninsula in Washington (National Park Service (NPS) 2009,
entire; Lofroth et al. 2010, p. 47). There is no evidence to indicate
that fisher in the USNRMs were recently, or historically, connected to
other fisher population centers in the United States (Gibilisco 1994,
p. 64; Proulx et al. 2004, p. 57). Maps of historical and recent fisher
distributions show no connection in the contiguous United States
between occurrences in the USNRMs and the fisher populations in the
Midwest and Great Lakes area, which occur approximately 1,126 km (700
mi) away, across mostly nonforested areas of unsuitable habitat
(Hagmeier 1956, p. 151; Douglas and Strickland 1987, p. 313; Gibilisco
1994, p. 64; Proulx et al. 2004, p. 57).
There is no indication that a population of fisher exists in a
large geographic area of southern Alberta or southern British Columbia
in Canada to the north of the USNRMs (see ``Distribution'' section).
Individual fishers have been identified near the international boundary
and observed using areas in both Canada and the USNRMs (Fontana et al.
1999, p. 19; Albrecht 2010, unpublished data; Giddings, 2010 pers.
comm.). We believe that the detections in extreme southern Canada
represent wandering individuals, or individuals in the USNRMs whose
home ranges include suitable habitat patches coincidental to the
border, because the closest concentration of fishers in Canada is over
200 km (125 mi) north of the USNRMs through patchy habitat of low
suitability (Weir 2003, p. 14; Weir and Lara Almuedo 2010, p. 36). The
lack of suitable habitat in southeastern British Columbia likely
contributed to the failure to reestablish a fisher population there in
the early 1990s (Fontana et al. 1999, p. 1; Weir et al. 2003, pp. 24-
25).
We have no direct confirmation that fishers are moving between the
USNRMs and larger population centers in Canada; however, it is likely
there is some interaction between transient individuals from the larger
population areas. Reports of transient or juvenile fishers moving
linear distances up to 135 km (84 mi) are known from other parts of the
fisher's range (Weir and Corbould 2008, p. 48), although shorter
distances of up to 107 km (66 mi) are more common (York 1996, p. 55).
It is unlikely that transient individuals provide a functional
connection between Canada population centers and the USNRMs.
Individuals traveling longer distances are subject to a greater risk of
mortality, and very few establish the stability of a home range (Weir
and Corbould 2008, p. 44) required for successful long-term
recruitment. Because the intervening areas appear unable to support
resident fishers, and we believe that the only fishers using these
areas are transient individuals attempting to move between population
centers, we have concluded that the USNRMs fisher population is
markedly separate from those to the north.
Summary for Discreteness
We conclude that the fisher in the USNRMs is markedly separated
from other populations of the same taxon as a result of physical
factors, and thus meets the definition of a discrete population
according to the Service's DPS policy. Because the entity meets the
first criterion for discreteness (marked physical separation), an
evaluation with respect to the second criterion (international
boundaries) is not needed.
Significance
If a population segment is considered discrete under one or more of
the conditions described in the Service's DPS policy, its biological
and ecological significance will be considered in light of
Congressional guidance that the authority to list DPSs be used
``sparingly'' (see Senate Report 151, 96th Congress, 1st Session) while
encouraging the conservation of genetic diversity. In making this
determination, we consider available scientific evidence of the
discrete population segment's importance to the taxon to which it
belongs. Since precise circumstances are likely to vary considerably
from case to case, the DPS policy does not describe all the classes of
information that might be used in determining the biological and
ecological importance of a discrete population. However, the DPS policy
describes four possible classes of information that provide evidence of
a population segment's biological and ecological importance to the
taxon to which it belongs. As specified in the DPS policy (61 FR 4722),
this consideration of the population segment's significance may
include, but is not limited to, the following:
(1) Persistence of the discrete population segment in an ecological
setting unusual or unique to the taxon;
(2) Evidence that loss of the discrete population segment would
result in a significant gap in the range of a 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.
A population segment needs to satisfy only one of these conditions
to be considered significant. Furthermore, other information may be
used as appropriate to provide evidence for significance. Below we
address conditions 1, 2, and 4. Condition 3 does not apply to fishers
in the USNRMs because North American fishers are distributed widely
within their historical range in Canada and the eastern United States.
Unusual or Unique Ecological Setting
The fisher is a forest-dependent species, and marked separation
from fishers in other geographic locations may be indicated by
variations in forest types or ecological conditions influencing forest
characteristics. Fishers in the western portion of the range (West
Coast, western Canada, and the USNRMs) generally inhabit landscapes
dominated by conifer forests, whereas fishers live in more dense,
lowland forests with higher proportions of deciduous trees in the
Northeast and upper Midwest United States and Canada (Allen 1983, pp.
2-3; Arthur et al. 1989b, p. 687; Powell 1993, p. 89; Buskirk and
Powell 1994, p. 285; Jones and Garton 1994 p. 377;
[[Page 38517]]
Ricketts et al. 1999, pp. 156, 160, 170). Fishers of the West Coast
population (Washington, Oregon, and California) inhabit forest
environments unusual in comparison to the rest of the taxon, and are
unique from other parts of the range based on the unusual forest
environment (69 FR 18777). Not only are the forests of the West Coast
fishers lacking the broadleaf forest component common in the eastern
range, but the coastal climate of wet winters and cool, dry summers
produces distinctive forests of sclerophyllic (leathery-leafed)
evergreen trees and shrubs found nowhere else in the range (Smith et
al. 2001 pp. 17-18; 69 FR 18777).
In addition to differences of forest type between the USNRMs and
eastern North America and the U.S. West Coast, fishers in the USNRMs
occupy forest areas that differ due to influences of climate and
precipitation patterns from fisher population areas in western Canada.
Forested areas of western Montana and central-to-northern Idaho are
temperate, coniferous forests influenced by dramatic elevation
gradients that produce several types of vegetation zones (Ricketts et
al. 1999, pp. 213-214, 250-251; Bailey 2009, p. 89, plate 1).
Topographic relief produces localized climate effects which add to the
vegetation variability within this region (Ricketts et al. 1999, pp.
213-214). Locally variable in predominant tree species or assemblages
of species, this temperate zone encompasses the USNRMs extending north
along the Continental Divide into southwestern Alberta and southeast
British Columbia (Ricketts et al. 1999, pp. 213-214).
The northern areas of the USNRMs are heavily influenced by maritime
moisture patterns, and in addition to the predominating Pseudotsuga
monziesii, Pacific tree species such as Thuja plicata (western red
cedar), Tsuga heterophylla (western hemlock) and Abies grandis are
present (McGrath et al. 2002, entire; U.S. Forest Service (USFS) 2009,
p. 1). Severe winters with heavy snowfall are usual and summers are
usually dry; precipitation is highly variable within the zone averaging
between 510 to 1,020 mm (20 to 40 in.) per year primarily falling as
snow in fall, winter, and spring (USFS 2009, p. 1). In the southern
part of the USNRMs, maritime conditions decrease along latitudinal and
altitudinal clines in the mountains of central Idaho and the Bitterroot
Range in west-central and southwest Montana (McGrath et al. 2002,
entire). A. grandis, P. monziesii, and western spruce/fir forests,
Larix spp. (larch), Pinus ponderosa and Pinus contorta (lodgepole pine)
characterize the mountain forests of the Idaho Batholith (Ricketts et
al. 1999, p. 250; McGrath et al. 2002, entire). Hardwood trees,
selected for fisher denning in other parts of the range, are not
significant parts of the landscape in the USNRMs (reviewed by Powell
1993, pp. 55-56; Heinemeyer and Jones 1994, p. iii; reviewed by Lofroth
et al. 2010, pp. 101, 108-109). The absence of hardwoods may be a
limiting factor to fishers in the region (Heinemeyer and Jones 1994, p.
iii), or an indication of successful adaptation to resources not used
elsewhere. Both of these points are speculative as there is little
information available describing natal den selection or successful
reproduction in the USNRMs.
Fishers in British Columbia and Alberta are associated most
commonly with the Sub-boreal Spruce and Boreal White and Black Spruce
Biogeoclimatic Zones in the central to northern areas of the provinces
(Weir and Lara Almuedo 2010, p. 36; Meidinger et al. 1991, p. 211;
Delong et al. 1991, p. 239). The Sub-boreal Spruce Zone is a heavily
forested montane region with uplands dominated by Picea engelmannii x
glauca (hybrid white spruce) and Abies lasiocarpa; Pinus contorta is
common on drier sites (Meidinger et al. 1991, p. 210). The climate of
the Sub-boreal Spruce Zone is continental and characterized by severe,
snowy winters and relatively warm, moist, and short summers (Meidinger
et al. 1991, p. 210). Mean annual precipitation ranges from 415 to
1,650 mm (16 to 65 in.) with less than half of that falling as snow in
winter (Meidinger et al. 1991, p. 210). The Boreal White (Picea glauca)
and Black (Picea mariana) Spruce Zone is a relatively dry zone with
very long, very cold winters with short summer growing seasons, and
annual precipitation averages between 330 and 570 mm (13 and 22 in.),
with 35 to 55 percent falling as snow (DeLong et al. 1991, p. 238). P.
glauca, P. mariana, P. contorta, and A. lasiocarpa are major tree
species in these zones (DeLong et al. 1991, p. 238). Both the Sub-
boreal Spruce and Boreal White and Black Spruce Zones have a
representative deciduous tree component of Populus tremuloides
(trembling aspen), Betula papyrifera (paper birch), and Populus
balsamifera spp. Trichocarpa (black cottonwood) (DeLong et al. 1991, p.
238; Meidinger et al. 1991, p. 212; Weir and Corbould 2008, p. 5), all
of which are tree hardwood types selected by fisher for reproductive
dens (Weir and Lara Almuedo 2010, p. 37).
Topographic relief in the USNRMs produces localized variations in
vegetation and seasonal snowfall not widely seen in the western Canada
population. It is hypothesized that fisher distribution on the
landscape is limited by deep snow (Krohn et al. 1995, p. 103; Krohn et
al. 1997, p. 226). If this is correct, then the precipitation in the
USNRMs, the majority of which falls as snow and is heavily influenced
by topography, could lead to geographic partitioning and an overall
less optimal habitat within the region. There are observations of
fishers using areas with deep, fluffy snow in the USNRMs, which also
could indicate an adaptation to local conditions, but the relationship
between using or avoiding certain snow conditions has not been
evaluated statistically. Fishers in Idaho have some of the largest home
ranges recorded for the species (reviewed by Powell and Zielinski 1994,
p. 58; IOSC 2010, p. 4; reviewed by Lofroth et al. 2010, p. 68),
possibly indicating suboptimal forest resources often found in
peripheral populations (Wolf et al. 1996, p. 1147). The limited
availability of hardwood tree types used for denning in other areas of
the range also may indicate a local adaptation to different den
structures in the USNRMs and the selection of less optimal structures
based on necessity.
More information is needed to elucidate important ecological
relationships for fishers in the USNRMs. Therefore, we do not conclude
that the fisher in the USNRMs is significant to the taxon as a whole
based on ecological differences alone, but the observed differences
indicate that fishers in the region are subject to suboptimal habitats
and pressures typically seen in important peripheral populations.
Strong selective pressures in peripheral populations may induce
adaptations that may be important to the taxon in the future.
Significant Gap in the Range of the Taxon
The loss of the fisher in the USNRMs would result in a significant
gap in the range of the taxon and contribute to the extensive range
retraction and fragmentation that has occurred since European
settlement of North America (Gibilisico 1994, p. 60). The USNRMs
represent one of only three historical peninsular reaches of the range
in the United States connecting with Canada and the southernmost
extension of the taxon's distribution in the Rocky Mountains (Gibilisco
1994, p. 60; Proulx et al. 2004, p. 57). Range retraction in the
eastern United States south of the Great Lakes has isolated populations
in New England and northern Atlantic States from Minnesota and
Wisconsin, although the eastern United States populations retain
connectivity to
[[Page 38518]]
Canada (Gibilisico 1994, p. 60; Proulx et al. 2004, p. 57).
Fisher populations in the western United States are isolated from
each other and the closest Eastern population in the Great Lakes area,
and have lost a connection or have a severely diminished capacity to
connect with larger population areas in Canada (Gibilisco 1994, p. 64;
Zielinski et al. 1995, p. 107; Aubry and Lewis 2003, pp. 86, 88; Weir
2003, pp. 19, 24, 25; Weir and Lara Almuedo 2010, p. 36). Extirpation
of the USNRMs population would significantly impact representation of
the species by shifting the southern boundary of the western range of
the taxon over 965 km (600 mi) to the north. Only three individually
isolated fisher populations in Oregon and California, two being native
populations (Aubry and Lewis 2003, p. 88; Lofroth et al. 2010, p. 47),
would be left in the entire southwest range of the taxon at a distance
of over 800 km (500 mi) from populations in Canada (Weir and Almuedo
2010, p. 36). The recent fisher introduction to Washington's Olympic
peninsula is not considered here because its establishment as a self-
sustaining entity has not been demonstrated.
The retention of a fisher population in the USNRMs is significant
to the taxon because of its situation at the periphery of the range.
Populations at geographic margins, defined as peripheral populations,
may be of high conservation significance and important to long-term
survival and evolution of species (Lesica and Allendorf 1995, p. 756;
Fraser 2000, p. 49). Populations at the periphery tend not to be given
conservation priority because of their existence in lower quality
habitats, and these populations are presumed to be least likely to
survive a reduction in range (Wolf et al. 1996, p. 1147). This
presumption is based on an existing theory that the cause of a species'
range contraction is erosion that commences at the periphery where
population numbers are low and progresses to the center where optimal
habitats support higher population numbers (Lomolino and Channell 1995,
pp. 336, 338). Upon closer examination, population persistence is not
biased toward larger, less isolated or more central regions of a
species historical range. Of 245 vertebrate species experiencing
geographic range contraction, 98 percent retained some species presence
in peripheral populations, 68 percent retained greater periphery than
core, and 37 percent of species retained no core but remained in
peripheral populations (Channell and Lomolino 2000, p. 85). Peripheral
populations are likely to be in suboptimal habitats and subject to
severe pressures that result in genetic divergence, as seen in USNRMs
fisher populations, either from genetic drift or adaptation to local
environments (Fraser 2000, p. 50). Because of their exposure to strong
selective pressures, peripheral populations may contain adaptations
that may be important to the taxon in the future. Lomolino and Channell
(1998, p. 482) hypothesize that because peripheral populations should
be adapted to a greater variety of environmental conditions, then they
may be better suited to deal with anthropogenic (human-caused)
disturbances than populations in the central part of a species' range.
We conclude that the loss of the USNRMs fisher population would
result in a significant gap in the range of the taxon by shifting the
southern boundary of the western range over 965 km (600 mi) to the
north, leaving only three individually isolated populations in the
entire southwestern range of the taxon. Thus, the USNRMs population
meets the definition of significant in our DPS policy.
Marked Genetic Differences
Fishers in the USNRMs represent a native lineage that escaped
extirpation early in the 20th century (Weckwerth and Wright 1968, p.
977; Schwartz 2007, p. 924). Close to half of the USNRMs fishers
sampled have a unique mitochondrial haplotype [a group of alleles (DNA
sequences) of different genes on a single chromosome that are closely
enough linked to be inherited usually as a unit]--Haplotype 12--found
nowhere else in the range of the taxon (Drew et al. 2003, p. 57; Vinkey
2003, p. 82; Vinkey et al. 2006, p. 269). Mitochondrial DNA is
associated with the energy-producing structures within cells called
mitochondria, and is inherited through the maternal line. Individuals
with Haplotype 12 are significantly divergent from all other haplotypes
in having an additional variation (Haplotype B) within a genetic
structure associated with the mitochondria called Cytochrome b, while
all of the other 11 mitochondrial haplotypes have the Haplotype A of
the Cytochrome b region (Vinkey 2003, p. 79; Vinkey et al. 2006, p.
268; Schwartz 2007, p. 923). Unique genetic haplotypes common to the
native lineage are expected, considering the peripheral location of the
population and a history of severe population reduction and isolation
(Lesica and Allendorf 1995, p. 754, Vinkey 2003, p. 82). Locally
adapted populations evolve traits that provide an advantage and higher
level of fitness under the local environmental conditions or habitat
than genotypes evolved elsewhere (Kawecki and Ebert, 2004, p. 1225),
and the unique genetic characteristics may have factored into
sustaining a rare population in the USNRMs. The forces that shape
adaptation are often strongest in the periphery of the range, and
populations situated here may be better suited to deal and adapt to
changes in their environments (Lomolino and Channell 1998, p. 482). It
is the intent of the DPS policy and the Act to preserve important
elements of biological and genetic diversity. The loss of the native
fisher lineage in the USNRMs would result in the loss of a unique and
irreplaceable genetic identity and the local adaptation and
evolutionary potential that goes with it. Thus, we conclude that the
USNRMs fisher differs markedly from other members of the taxon in
genetic characteristics, and this difference is significant to the
conservation of the species.
Summary for Significance
We conclude that the fisher population in the USNRMs is significant
because its loss would result in a significant gap in the range of the
taxon, and its genetic characteristics differ markedly from those of
other fisher populations.
Determination of Distinct Population Segment
Based on the best scientific and commercial information available,
we find that the fisher in the USNRMs is both discrete and significant
to the taxon to which it belongs. Fishers in the USNRMs are markedly
separated from other populations of the same taxon as a result of
physical factors, further supported by quantitative differences in
genetic identity. The loss of the fisher in the USNRMs would result in
a significant gap in the range of the taxon and the loss of markedly
different genetic characteristics relative to the rest of the taxon.
Because the fisher in the USNRMs is both discrete and significant, it
qualifies as a DPS under the Act.
Distinct Population Segment Five-Factor Analysis
Since the fisher in the USNRMs qualifies as a DPS, we will now
evaluate its status with regard to its potential for listing as
endangered or threatened under the five factors enumerated in section
4(a) of the Act.
Section 4 of the Act (16 U.S.C. 1533) and implementing regulations
(50 CFR part 424) set forth procedures for adding species to, removing
species from, or
[[Page 38519]]
reclassifying species on the Federal Lists of Endangered and Threatened
Wildlife and Plants. Under section 4(a)(1) of the Act, a species may be
determined to be endangered or threatened 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; or
(E) Other natural or manmade factors affecting its continued
existence.
In making this finding, information pertaining to the USNRMs fisher
DPS in relation to the five factors provided in section 4(a)(1) of the
Act is discussed below. In making our 12-month finding on the petition
we considered and evaluated the best available scientific and
commercial information.
In considering what factors might constitute threats to a species,
we must look beyond the exposure of the species to a particular factor
to evaluate whether the species may respond to that factor in a way
that causes actual impacts the species. If there is exposure to a
factor and the species responds negatively, the factor may be a threat
and, during the status review, we attempt to determine how significant
a threat it is. The threat is significant if it drives, or contributes
to, the risk of extinction of the species such that the species
warrants listing as endangered or threatened as those terms are defined
in the Act. However, the identification of the factors that could
impact a species negatively may not be sufficient to compel a finding
that the species warrants listing. The information must include
evidence sufficient to suggest that these factors are operative threats
that act on the species to the point that the species may meet the
definition of endangered or threatened under the Act.
We are required by the Act to assess threats information that may
occur within the foreseeable future. We define foreseeable future as a
timeframe in which impacts can be reasonably expected to occur. Where
future projections are not available, it is assumed that current trends
will continue unless information exists to the contrary. Our evaluation
of the fisher in the USNRMs follows.
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 fisher
habitat including: (1) Timber Harvest and Forest Management, (2)
Development and Roads, (3) Climate Change, and (4) Fire and Disease.
Climate change is discussed under Factor A, because the primary impact
of climate change on fishers is expected to be through changes to the
availability and distribution of fisher habitat. Many of these impact
categories overlap or act together to affect fisher habitat.
Timber Harvest and Forest Management
Industrial timber harvest in the inland Northwest United States
(Interior Columbia River Basin), including Idaho and western Montana,
did not occur until the early 20th century (Hessburg and Agee 2003, pp.
40-41). Prior to 1900, logging in Idaho and Montana supplied timbers
only to local concerns such as mining and railroad development, and did
not become important to national markets until after other forested
areas (e.g., Great Lakes region) had been depleted (Hessburg and Agee
2003, p. 40). Early industrial logging used selective practices, taking
only large, high-grade or salvage logs (Hessburg and Agee 2003, pp. 41-
42). By 1940, many inland northwest areas containing dry forest types,
typically of ponderosa pine, were intensively logged by this method;
moist or mesic forest types favored by fishers in the Flathead Valley
and Whitefish Mountains in Montana and the Coeur d'Alene area of
northern Idaho were also affected (Lesica 1996, p. 34; Hessburg and
Agee 2003, pp. 41-42). The balance of forested areas in Idaho and
Montana showed little or no logging activity up to 1940 (Hessburg and
Agee 2003, p. 42).
Historical fisher population numbers are not known, but reports of
their presence declined in the 1920s to a point that the fisher was
presumed extirpated in the USNRMs (Williams 1963, p. 8; Weckwerth and
Wright 1968, p. 977; Brander and Books 1973, p. 52). Fishers in the
USNRMs avoid dry forest types (Schwartz 2010, unpublished data), and
because local subsistence logging and early industrial logging were of
limited geographic scale and selected for dry forest types, it is
unlikely that this contributed directly to the fishers' apparent demise
across the USNRMs area. Other factors or combination of factors,
discussed in subsequent sections, may have had more influence on past
fisher population reductions.
From the 1930s, timber harvest continued (Hessburg and Agee 2003,
p. 41) while native fishers maintained an undetected refugium likely,
in the Selway-Bitterroot Mountains straddling the border of Montana and
Idaho (Vinkey et al. 2006, p. 269). Timber harvest was increasing in
the USNRMs as fisher reintroductions (later realized to be population
augmentations) were occurring in the late 1950s and early 1960s.
Clearcutting practices, which removed all overhead cover in the harvest
area, increased on private and public lands, and large areas of private
timberland were converted to plantation forestry which emphasized
clearcutting and even-aged forest regeneration management practices
(Hessburg and Agee 2003, p. 41). With plantation or rotational
forestry, the large tree components and coarse woody debris are
suppressed or not allowed to accumulate to the point that they supply
denning or cold weather resting sites (Weir 2003, p. 16). From 1938 to
present day, low-elevation timberlands have been depleted of large,
older trees considered late-seral or old-growth type, and the mid-
elevation habitats retain only small amounts (DellaSala et al. 1996, p.
213; Lesica 1996, p. 37). The majority of presettlement upland old-
growth forest was in the drier forest types of ponderosa pine/Douglas
fir/western larch, which are subject to frequent low-intensity
underburns that reduce ladder fuels (forest fire fuels that provide
fire connectivity from understory to midlevel or canopy fuels) and more
shade-tolerant vegetation in the understory (Green et al. 1992, p. 2).
However, fishers are known to avoid these forest types and they
represent only minor components of areas used by fishers (Jones and
Garton 1994, pp. 377-378; Schwartz 2010, unpublished data).
In general, timber harvest and management over the last century has
resulted in the loss of old forest and large- and medium-diameter trees
that historically were widely distributed in forest structures other
than old growth forest (Hessburg and Agee 2003, p. 45); still, the
amount of land covered by forest in the USNRMs is similar to historical
times (Hessburg et al. 2000, p. 60). Timber harvest, together with fire
exclusion, has produced younger, homogenously structured forest
patches, especially in dry forest types, with more canopy layers and
more understory vegetation than historically due to fire suppression
(Hessburg and Agee 2003, pp. 45-46). Fragmentation of managed
landscapes has increased due to more numerous and smaller patches of
various forest types, while roadless and wilderness areas have retained
a simpler less fragmented structure (Hessburg et al. 2000, p. 78). From
a landscape perspective, the departure from historical old-growth
structure is most
[[Page 38520]]
pronounced in the northern areas of the USNRMs, with a concurrent shift
to increasing old-forest multistory stages in the southern areas
(Wisdom et al. 2001, p. 184).
As a result of timber harvest and management practices, forest
structures and quantities of large trees across the USNRMs have been
affected. It is unclear how this has impacted fisher populations. There
is no information regarding fisher population numbers within the region
before European settlement, and no region-wide population numbers or
trends are available today to allow a comparison of the impacts of
changes to the landscape over time on fisher populations. Fishers were
so rare as to be considered extirpated before large-scale harvesting
occurred. Fifty years after the introduction of 78 animals to 9 areas
in Idaho and Montana between 1959 and 1962 (reviewed by Vinkey 2003, p.
55), concurrent with decades of post-introduction timber harvest,
fishers, half of which are of native lineage, persist on the landscape
in a wider distribution than they did before augmentations (Vinkey
2003, p. 82; IOSC 2010, pp. 7, 10; MTFWP 2010, Attachment 4). Although
there is little information elucidating the density of fisher
populations in the USNRMs, the contemporary distribution of fishers
appears to be similar to the historically depicted distribution in
Idaho and Montana (Gibilisco 1994, p. 64) (Figure 1).
We are not concluding that a cause and effect relationship exists
between increased timber harvest or treatment and increasing fisher
distribution. The existing state of the USNRMs landscape is conducive
to supporting fisher, but it is unknown if the system has the capacity
to support, in the long term, a self-sustaining population or
subpopulations in a metapopulation dynamic. Fisher home ranges in Idaho
and Montana are larger than most other areas in the taxon's range
(reviewed by Powell and Zielinski 1994, p. 58; reviewed by Lofroth et
al. 2010, p. 68; IOSC 2010, p. 4), and this large size could be the
result of fragmentation or low-quality habitat (Powell and Zielinski
1994, p. 60), either naturally occurring or human-produced. Timber
harvest and management have significant potential to alter the
suitability of a landscape for fishers; conversely, management of
forests using mechanical means or fire can assist in creating
conditions that foster larger trees, create snags, increase woody
debris, or open densely stocked areas to provide habitat for fisher
prey species. Fishers in the USNRMs evolved in forest types where fire
frequency and intensity was mixed, and windthrow was common, resulting
in a complex and intricate landscape mosaic of young, mixed-age, and
late-seral components (Jones 1991, p. 111; Arno et al. 2000, pp. 225-
227). Thus, the result of silviculture treatments or harvest may
resemble the natural disturbances and the succession that follows
(Powell and Zielinski 1994, p. 64).
Current and Future Timber Harvest and Management
Commercial timber harvest, management for timber production, and
the use of forestry techniques to protect, restore, and enhance forest
ecosystems are ongoing activities in the USNRMs and are expected to
continue. Fourteen national forests comprise approximately 65 percent
of the land area and 72 percent of the forest types known to be used by
fishers in the USNRMs (U.S. Department of Agriculture (USDA) 2009,
entire). Timber harvest or manipulation for either timber production or
other resource objectives is stated in each forest's Land and Resource
Management Plan, which provide direction for a 10- to 15-year period.
National forests are subject to a multi-use mandate and maintenance
``in perpetuity of a high level of annual or regular periodic output of
the various renewable resources,'' including timber (PL 104-333), and
other legislative mandates for forest health or fuels reduction (e.g.,
Healthy Forests Restoration Act (Pub. L. 108-148)), which may require
manipulation of forested areas. Planning directives specify lands for
timber production for long-term sustained yields; however, silviculture
(forest removed or treated) acres on all forests in the USNRMs has
generally declined over the past 15 years, including a significant
reduction in clearcutting (USDA 2010a, entire; USDA 2010b, entire). The
USFS actions are regulated and relevant authorities are discussed in
the ``Factor D'' section below.
State-owned forestry lands comprise approximately 6 percent of the
forest types preferred by fishers in the USNRMs area. Timber harvest is
an activity expected to continue on State trust or endowment lands in
both States of Idaho and Montana, because of the responsibility to
maximize long-term financial returns to public schools and other trust
beneficiaries (Idaho Board of Land Commissioners 2007, p. 3; Montana
Code Annotated 2009a, entire). Forest resources are evaluated for
management of a sustainable harvest on 5- to 10-year review schedules
(Idaho Board of Land Commissioners 2007, p. 18; Montana Department of
Natural Resources and Conservation (MTDNRC) 2010, p. 3). Private lands,
including commercial timber operations with the primary objective of
maximizing fiber production, comprise approximately 22 percent of the
fisher forest types. The extent of timber harvest operations are driven
by market forces and difficult to predict (Morgan et al. 2005, p. 2),
but it is reasonable to conclude that management to maximize wood
production (e.g., pre-thinning of stands), harvest, road construction
and maintenance, and other activities will continue into the future.
We expect the current timber management and silviculture activity
to continue on national forest lands guided by management plans. The
effects of present and future forest management and timber harvest on
the capacity of the USNRMs to support fishers may be influenced by many
factors, including the location, scale, and juxtaposition of treatments
to previous disturbances; the suitability of an area to provide fisher
habitat under natural conditions; and the habitat needs of fishers. The
habitat ecology of fishers in the USNRMs is not well understood. Forest
patches with high densities of large trees, canopy covers exceeding 40
percent, and riparian areas appear to be important; however,
information is lacking regarding fishers' requirements for patch size
and connectivity (Jones and Garton 1994, pp. 380, 385-386). Although
some information is available from other regions, habitat requirements
for successful denning and rearing of young in the USNRMs are not
known. Fishers have been described as using ``old-growth'' forest types
disproportionally to their occurrence (Thomas et al. 1988, p. 255);
however, there also has been a lack of clarity in the use of the term
``old-growth'' in forest ecology literature, and description of forest
characteristics at any particular successional stage vary by geographic
region, forest type, and local conditions (Green et al. 1992 errata
2008, p. 2). Therefore, without specific parameters, basing a loss of
fisher habitat on trends of ``old-growth'' or even ``larger trees'' may
be misleading.
Late seral or mature forest elements such as snags and overhead
cover are important habitat features for fishers throughout their
range. These mature forest conditions may take many decades to hundreds
of years to develop, and national forest management direction is
revised over short time periods relative to forest succession. National
forest lands that support fishers today reflect natural processes and
silviculture actions
[[Page 38521]]
spanning numerous planning periods as well as actions taken before
comprehensive national forest management was mandated in 1976 (16 U.S.C
1601-1614). Given the history of forest management and planning, we do
not expect significant changes in the availability of mature forest
habitats through future forest planning cycles.
The species continues to occupy its presumed historical range
despite habitat alterations that have occurred within that range,
although fisher densities may be different. Fishers in the USNRMs have
been observed to use roadless areas of forests, national forest lands
managed for multiple purposes, and State forests and industrial forests
managed primarily for commercial timber production (J. Sauder, IDFG,
unpublished data cited in IOSC 2010, p. 4), although it is unclear how
fishers are using these environments, or the relative importance of
each to supporting individuals or fisher populations. We expect that
fishers' use of lands managed for timber production or multiple uses
will occur in the future under conditions fostered by the continuance
of current management. Therefore, we conclude that the best available
scientific and commercial information does not indicate that current or
future forest management practices and timber harvest threaten the
fisher now, or in the foreseeable future.
Development and Roads
The USNRMs region encompasses large tracts of public lands with
little or no development, wilderness areas, and numerous municipalities
of varying size, low-density rural development, rail lines, road
networks and other human developments. Most of the development and
infrastructure, including national forest roads, have been on the
landscape for decades (Baker et al. 1993, p. 2; Havlick 2002, p. 11).
Higher density development and road networks are situated in broad,
open, lower-elevation intermountain valleys or lower montane areas, and
most human activity and dwellings adjacent to public lands occur in dry
woodlands or dry forest (Hessburg and Agee 2003, p. 47). Development in
most cases is not far from public lands--primarily national forest.
Mesic forest types and riparian corridors preferred by fishers are
generally found at low to mid-elevations, and these highly productive
habitats often coincide with areas that receive above average levels of
human use (Carroll et al. 2001, p. 962). Where development and roads
coexist with these areas, habitat could be lost directly by replacement
with infrastructure or removal of cover, and fishers could be impacted
by increased susceptibility to direct mortality from vehicle
collisions, and increased exposure to disease from pets and animals
such as raccoons associated with human development (Ruediger 1994, p.
3; Carroll et al. 2001, p. 969; Brown et al. 2008, p. 23). We have no
information that disease is a problem for fishers in the USNRMs, and
reports of fisher mortality due to vehicle collision are few (Vinkey
2003, p. 32; Giddings 2010, pers. comm.) (see Factor C discussion
below).
The secondary effects of human activity and infrastructure, and
roads or road use, in causing fisher avoidance or inhibiting movement
on the landscape are unclear. It is reported that fishers in California
more often used areas with a greater than average density of low-use
roads (Dark 1997, p. 50), and, in Maine, fishers seldom traveled in the
vicinity of roads or powerline corridors (Coulter 1966, p. 61).
Conversely, Arthur et al. (1989b, p. 687) found that fishers in Maine
were fairly tolerant of human activity, including low-density housing,
farms, roads, and gravel pits, if forest canopy cover was maintained in
the vicinity. Roads in forested areas of the USNRMs are often
constructed along riparian corridors or forested valley bottoms, which
are habitats fishers prefer. Targeted surveys for fishers are often
conducted near roads because of the ease of access and likelihood of
detecting fisher in a preferred habitat. Fishers do not avoid areas
adjacent to a minor State highway that traverses National Forest land
in Idaho (Schwartz et al. 2007, p. 6), and other targeted survey
efforts for fishers in northern Idaho have successfully detected
fishers in the vicinity of roads (Schwartz et al. 2007, p. 6; Albrecht
and Heusser 2009, p. 8). This would imply that fishers are not
displaced from suitable habitat by the presence of roads or road use.
Roads and landscape features such as rivers have been implicated in
increasing mortality risk to dispersing fishers, but fishers have
dispersed across, and did not appear to be affected by roads, lakes or
rivers in other parts of the range (York 1996, p. 46; Fontana et al.
1999, pp. 17; Weir and Corbould 2008, p. 44).
Roads constructed on public lands to provide access for resource
use and extraction have been implicated in increasing access for
trappers that target fishers or that may accidentally trap them
(Hodgman et al. 1994, p. 598). The closure of roads to provide grizzly
bear (Ursus arctos) habitat security is a possible reason for the
reduction in fishers harvested in Montana's Flathead and Swan Valley
(Giddings 2010, pers. comm.). Recent changes in the USFS' travel
management direction (70 FR 68264, November 9, 2005), require that
national forest roads are managed in a manner compatible with wildlife
resources. Accordingly, implementation of seasonal or permanent road
closures to benefit the threatened grizzly bear has likely provided
benefits to fishers in many parts of the USNRMs.
Rapid housing growth has occurred in close proximity to public
lands in the Rocky Mountain region since the 1990s, with much of it
situated in areas already considered wildland-urban interface and
impacted by development (Alig et al. 2010, p. 9). Additional
residential development adjacent to public lands is expected to
increase by 10 to 42 percent in some areas of the USNRMs by 2030 (Stein
et al. 2007, p. 8). The sale of private nonindustrial lands (i.e.,
family-owned forests) currently managed for timber is a likely source
for additional residential development (Alig et al. 2010, pp. 6-7),
although it is uncertain if a significant quantity of these lands is
mesic forest or dry forest type less suitable for fishers.
There is a trend of large, industrially managed or corporate forest
properties being divested for real estate development across the United
States that is expected to continue into the future. Although large
areas of industrial forest are predicted to be lost nationwide through
2050, most of this loss is due to urbanization in the southern United
States (Alig et al. 2010, pp. 14-15). We know that fishers utilize
industrial forests in the USNRMs (IOSC 2010, p. 4). The availability of
industrial forest lands for other uses will likely improve conditions
for fishers in Montana, where over 1,253 km\2\ (484 mi\2\) of low-
elevation commercial forest, originally intended to be sold for
development purposes was instead purchased for conservation and
sustainable forestry by State, Federal, and conservation organizations
(MTFWP 2010, Appendix 13, entire; The Nature Conservancy 2010, entire).
Dwellings, roads, and other infrastructure have been on the
landscape for decades, and areas currently developed will see an
increase in the density of development over the next 20 years. It is
unknown if fisher habitats that are currently or potentially suitable
will be affected directly by future development. The proximity and
availability of public lands may moderate a loss of habitat if it
occurs, but the impact to fishers is uncertain because of a lack of
understanding of how fishers use the lands at the interface of public
and private ownerships. Increased road traffic and
[[Page 38522]]
human presence and recreational demands on public lands may increase
the risk to fisher of vehicle collisions and displacement from suitable
habitats near areas of high human use. Reports of fishers' responses to
human activity and the presence of roads are mixed and, therefore,
difficult to conclude with certainty. Habitat loss and increased direct
mortality resulting from increasing human development are a concern
but, based on the available information, do not rise to a level of
threat to the USNRMs fisher now, or in the foreseeable future.
Climate Change
We know of no element of the fisher's ecology or physiology that
would be directly affected by changes in climate. Predicted climate
changes could impact forested environments upon which fishers depend;
therefore, we address climate change under Factor A.
Climate is influenced primarily by long-term patterns in air
temperature and precipitation. The Intergovernmental Panel on Climate
Change (IPCC) concluded that climate warming is unequivocal, and
evident from observed increases in global average air and ocean
temperatures, widespread melting of snow and ice, and rising global
mean sea level (IPCC 2007a, pp. 30-31). Continued greenhouse gas
emissions at or above current rates are expected to cause further
warming (IPCC 2007a, p. 30). Eleven of the 12 years from 1995 through
2006 rank among the 12 warmest years in the instrumental record of
global average near-surface temperature since 1850 (Independent
Scientific Advisory Board (ISAB) 2007, p. 7; IPCC 2007a, p. 30). During
the last century, mean annual air temperature increased by
approximately 0.6 [deg]C (1.1 [deg]F) (IPCC 2007a, p. 30). Warming
appears to be accelerating in recent decades, as the linear warming
trend over the 50 years from 1956 to 2005 (average 0.13 [deg]C or 0.24
[deg]F per decade) is nearly twice that for the 100 years from 1906 to
2005 (IPCC 2007a, p. 30). Climate change scenarios estimate that the
mean air temperature could increase by over 3 [deg]C (5.4 [deg]F) by
2100 (IPCC 2007a, pp. 45-46). The IPCC also projects that there will
likely be regional increases in the frequency of hot extremes, heat
waves, and heavy precipitation, as well as greater warming in high
northern latitudes (IPCC 2007a, p. 46). We recognize that there are
scientific differences of opinion on many aspects of climate change,
including the role of natural variability in climate. In our analysis,
we rely primarily on synthesis documents that present the consensus of
a large number of experts on climate change from around the world, as
well as the scientific papers used in those reports, to represent the
best available scientific information. Where possible, we used
empirical data or projections specific to the western United States,
which includes the Northern Rocky Mountain region, and have focused on
observations or expected effects on forested ecosystems.
Specific regional projections for the Interior Columbia Basin and
the USNRMs are warmer temperatures, with more precipitation falling as
rain than snow, diminished snowpack and altered stream flow timing,
increase in peak flow of rivers, and increasing water temperatures
through the 21st century (to 2099) (Hansen et al. 2001, p. 769; ISAB
2007, pp. iii, 15-16). The consequences of these projections are
unclear and could result in positive, negative, or neutral impacts to
fisher habitat and populations. Fisher habitat could expand due to
warming temperatures extending the growing season and increased
atmospheric carbon dioxide escalating vegetation growth and extending
forest area (Millar et al. 2006, pp. 48-49). It is hypothesized that
climate change will produce greater tree species richness over much of
the coterminous United States because of the current relatively greater
species richness in warmer climates (Hansen et al. 2001, p. 774). The
potential habitats of dominant rainforest conifers (e.g., western
hemlock and red cedar that fishers use in the USNRMs) are expected to
decrease west of the Cascades but expand into mountain ranges of the
interior West (ISAB 2007, p. 26). If the hypothesis that fishers are
limited by deep winter snow is correct (Raine 1981, p. 74; Krohn et al.
1997, p. 226), decreased winter snowfall could increase the habitat
available to fishers.
Changes in temperature and rainfall patterns are expected to shift
the distribution of ecosystems northward (IPCC 2007b, p. 230) and up
mountain slopes (McDonald and Brown 1992, pp. 411-412; IPCC 2007b, p.
232). Predicted climate shifts over the next century could result in
the loss of alpine and subalpine spruce-fir forests, for example,
forcing competition for prey between fishers and predators that are now
occupying higher elevation niches (e.g., lynx) (Koehler 1990, p. 848;
Ruediger et al. 2000, p. 3), or novel predator-prey interactions could
evolve (ISAB 2007, pp. 26, 28). Increasing temperatures without
additional moisture could stress vegetation, alter riparian systems,
increase fire risk, and increase the susceptibility of forest
vegetation to disease (Westerling et al. 2006, p. 943; ISAB 2007, pp.
19, 25). Riparian areas are used extensively by fishers in the USNRMs
(Jones 1991, pp. 90-93). Changing water regimes or decreased flow could
decrease the productivity of riparian species and affect vegetation
structure necessary for prey and security cover. The potential effects
of climate change on the health of riparian systems could be
exacerbated by the demands from increasing human population,
development, and land use (Hansen et al. 2002, p. 159).
Projected changes of climate could result in a wide range of
potential outcomes for fishers and their habitat. The effects to
fishers in either the short or long term in a focused geographic area
cannot be reasonably discerned without a specific aspect of the
species' ecology or physiology linked to a confidently projected
climate change variable (e.g., water temperature tolerance of fish, or
early snowmelt reducing wolverine denning). Increasing temperatures and
drought could affect fire frequency and intensity and the
susceptibility of forest vegetation to disease, but climate change
itself does not represent a threat to fishers now or in the foreseeable
future.
Fire and Disease
Fire disturbance was an integral force in shaping the Northern
Rocky Mountains forest ecosystem well before European settlement of the
region (Lesica 1996, p. 33). Lower, drier elevations were prone to
frequent, low-intensity burns, while cool high-elevation forests were
subject to intense stand-replacing events at intervals up to 300 years
(reviewed by Hessburg and Agee 2003, p. 27). The grand fir/hemlock/
cedar forests known to support fisher today in Idaho have a history of
highly variable mixed-intensity fire regimes. Fire severity and return
intervals varied widely ranging from low-intensity fires with 16-year
return intervals, to high-severity fires with 500-year return intervals
(reviewed by Hessburg and Agee 2003, p. 27). Pre-European settlement
forests would likely have been in a shifting mosaic of different
successional stages, with 4 to 46 percent of the landscape of trees
older than 200 years old (reviewed by Lesica 1996, p. 37). A fire
history from 1650 to 1900 reveals that local fires or no fires occurred
in most years. Occurring less often were extensive regional fire events
in warm, dry summers that were preceded by warm springs: Eleven of
these events occurred in the 20th century (Morgan et al. 2008, p. 723).
One of the largest regional fires
[[Page 38523]]
of the 20th century occurred in 1910, consuming over 11,675 km\2\ (4507
mi\2\) in northern Idaho and scattered locations in northwest Montana
(Morgan et al. 2008, p. 721). Regional fires in the early 1900s
consumed more mesic forest than regional fires in later years (Morgan
et al. 2008, p. 725). It has been suggested that the 1910 and 1934 fire
events, in combination with overharvest by the fur industry,
contributed to the fisher population decline (Jones 1991, p. 1).
Active fire suppression by humans in the mid-20th century has been
implicated in the accumulation of forest vegetation believed to
contribute to more fire-prone conditions today (Hessburg and Agee 2003,
pp. 44, 46). However, a remarkable period between 1935 and 1987 was the
longest period of low fire activity of the previous 250 years, and the
lack of large fire activity was more a factor of cooler, wet climate
conditions than fire suppression action (Morgan et al. 2008, p. 726).
An abrupt change occurred in the 1980s from a fire regime of infrequent
large fires of short duration, to more frequent longer burning fires
(Westerling et al. 2006, p. 942). The shift was associated with
unusually warm springs, longer summer dry seasons associated with
reduced winter precipitation, and early spring snowmelt (Westerling et
al. 2006, p. 943), a climate pattern seen with historical regional fire
regimes.
Since the 1980s, the Northern Rocky Mountains have seen the largest
absolute increase in large wildfire activity in the forest types least
affected by previous fire exclusion: Mesic mid-elevation and high-
elevation forest types (Westerling et al. 2006, p. 943). Climate model
projections indicate decreased snowpack, earlier snowmelt, and
increasing temperatures contributing to longer fire seasons (Westerling
et al. 2006, p. 943). Moisture patterns are more difficult to predict
than temperature (Global Climate Change Impacts 2009, p. 135; Dai 2011,
p. 16). Because many climate models predict higher precipitation levels
associated with climate warming, the interaction between precipitation
and temperature increase can be quite complex. If temperatures increase
without compensating moisture patterns or amounts, the predicted warmer
springs and summers could produce conditions favorable to the
occurrence of large fires in the future, regardless of past trends
(Westerling et al. 2006, p. 943). If this occurs, increased fire
frequency and intensity in forests could increase the likelihood of
direct fisher mortality, diminish the capacity of the landscape to
support fisher, and increase isolation of small fisher populations on
the landscape.
Diseases that affect forest structure and composition could impact
fisher habitats by reducing cover or altering prey availability. Bark
beetle (Dendroctonus spp.) eruptions have been affecting forest
structure for millennia, but recent drought and increased winter
temperatures have contributed to unprecedented rates of beetle
infestations in lodgepole and ponderosa pine in the western United
States (Brunelle et al. 2008, pp. 836-837). Lodgepole forests in
British Columbia are a significant habitat type for fishers in British
Columbia, and these forests have experienced widespread mortality from
beetle infestation (Weir and Corbould 2010, p. 409). Infestations are
widespread in forested areas of Idaho and western Montana (MTDNRC 2009,
entire; Idaho Department of Lands 2010, entire), but the affected
forest types are a small component of fisher habitat in the USNRMs
(Jones and Garton 1994, pp. 377-378). Mortality of the overstory occurs
in affected stands, but fisher use may not be affected if sufficient
secondary structure remains (Weir and Corbould 2010, p. 409). Over
time, affected trees or stands could provide standing (vertical) rest
and den sites as well as contributing to downed woody debris in the
understory (Simard et al. in press, p. 2). Standing beetle-killed trees
have been considered a significant fire hazard which could fuel larger,
landscape fires (Bentz et al. 2010, p. 611). Recent studies indicate
that this concern could be overstated as neither torching nor crowning
would be expected to increase with dead standing trees with retained
needles, and the likelihood of sustaining an active crown fire in dead
stands significantly decreases with tree collapse (Simard et al. in
press, pp. 2, 28).
Disease processes are natural forces in shaping forest environments
and may be important in providing denning or resting structures for
fishers. We have no information that the current bark beetle epidemic
is negatively impacting fisher habitat or fishers in the USNRMs. An
increase in incidence of forest diseases or novel diseases also could
accompany a changing climate, but as with fire, the threat to fisher
habitats is difficult to predict. Based on the available information,
climate driven events such as regional fires or disease and insect
infestations do not rise to the level of threat to the fisher now or in
the foreseeable future.
Summary of Factor A
The fisher is a forest-dependent species that evolved in the USNRMs
in a complex landscape mosaic shaped by fire, tree disease, and
windthrow. In the USNRMs, younger forests provide foraging habitat, but
abundant mature and old trees that provide extensive canopy cover for
resting and possibly denning are also considered important elements to
support fishers on the landscape. Fisher populations were greatly
reduced to the point they were believed extirpated in the USNRMs in the
early 20th century. Human occupation and commercial timber harvest
occurred at low levels early in the century, and anthropogenic
alteration of fisher habitat is an unlikely cause of the species'
population collapse in this region. Over decades, fisher populations
resurged, with the help of augmentations, concurrently with natural
climate events such as drought and fire, and also the permanent or
long-lasting effects of development and timber harvest that potentially
alter the important mature forest structure.
Fourteen national forests comprise approximately 72 percent of the
forest types known to be used by fishers in the USNRMs, State forestry
lands 6 percent, and private lands including industrial timber lands
comprise approximately 22 percent (USDA 2009, entire). Commercial
timber harvest, management for timber production or fuels reduction
(such as pre-commercial thinning), prescribed burning, recreation and
road maintenance and use are ongoing in the region and we expect these
activities to continue. Fishers have been observed to use roadless
areas of forests, national forest lands managed for multiple purposes,
and State forests and industrial forests managed primarily for
commercial timber production. It is unclear how fishers are using these
environments, or their relative importance to supporting individuals or
fisher populations. However, habitats supporting fishers today reflect
past and current forest management, silviculture, and natural
processes, and we do not expect future changes in the management of
forest conditions to significantly vary from current direction.
Based on the limited available survey information, the contemporary
distribution of fishers is similar to the historically depicted
distribution in Idaho and Montana, despite alterations that have
occurred within its range. Current fisher population numbers or trends
are unknown. The existing state of the USNRMs landscape is conducive
[[Page 38524]]
to supporting fisher, but it is not clear what the capacity of the
system is to support, in the long-term, a self-sustaining population or
a metapopulation dynamic of subpopulations. Interpreting the impact of
past and present forest management, resource extraction, or development
is complicated by an incomplete picture of how the animals are using an
altered landscape. Given the available information, it does not appear
that forest management and timber harvest are threats to the species
currently or in the foreseeable future.
Dwellings, roads, and other infrastructure have been on the
landscape for decades, and currently developed areas likely will see an
increase in the density of development over the next 20 years. It is
unknown if fisher habitats that are currently or potentially suitable
will be affected directly by future development. The proximity and
availability of public lands may moderate a loss of habitat, if it
occurs, but more needs to be understood regarding how fishers are using
the lands at the interface of public and private ownership. An increase
in traffic on roads, and increased human presence and demands for
recreation on public lands also, may increase the risk of vehicle
collision and displacement from suitable habitats in proximity to areas
receiving high levels of human use. Reports of fishers' responses to
human activity and the presence of roads are mixed and, therefore,
difficult to conclude with certainty. Habitat loss and increased direct
mortality resulting from increasing human development are a concern,
but, based on the available information, do not rise to a level of
threat to the population.
The Northern Rocky Mountain region has a history of local and
periodic regional fire and tree disease events. Fire and disease will
continue to shape the forest landscape. While most climate predictions
through the 21st century include increased temperature and earlier
spring snowmelt conducive to longer fire seasons, the uncertainty of
moisture patterns makes regional fire patterns difficult to predict.
Forests in the USNRMs are vulnerable to an increasing frequency of
large fires, which could lead to changes in forest composition and
structure, cause direct fisher mortality, diminish the capacity of the
landscape to support fisher, and isolate small populations in a matrix
of unsuitable habitat. Although the potential for changing fire
frequency and intensity exists, these events cannot be predicted with
confidence. The current incidence of bark beetle infestation does not
appear to represent a significant threat to fishers in the USNRMs. An
increase in incidence of forest diseases or novel diseases also could
accompany a changing climate, but as with fire, the threat to fisher
habitats is difficult to predict. Based on the available information,
climate-driven events such as regional fires that may result from
projected increases in temperature, earlier spring snowmelt and
drought, or the increased susceptibility of trees to disease or insects
due to drought, do not rise to the level of a threat to the fisher in
the foreseeable future.
We conclude that the best scientific and commercial information
available indicates that the fisher in the USNRMs is not now, or in the
foreseeable future, threatened by the present or threatened
destruction, modification, or curtailment of its habitat or range to
the extent that listing under the Act as an endangered or threatened
species is warranted at this time.
Factor B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Unregulated overharvest, and the use of strychnine as a trapping
and general predator control agent, in addition to habitat loss,
eliminated or greatly reduced fisher numbers across the range by the
mid-1900s (Douglas and Strickland 1987, p. 512; Powell 1993, p. 77).
The closure of trapping seasons in the 1920s and 1930s, reintroductions
and augmentations, and land-use changes helped restore the fisher's
presence in many parts of its range (Douglas and Strickland 1987, p.
512; Powell 1993, p. 80; Drew et al. 2003, 59; Vinkey 2003, p. 61). The
role of land use changes with respect to the increase in fisher
presence in the USNRMs is less clear (see Factor A section), but the
regulation of trapping and end to indiscriminate predator control has
likely had a positive influence. Trapping seasons were reopened in many
northeastern and Midwestern States, including Montana, between 1949 and
1985, with accompanying regulations intended to prevent overtrapping
and population decline (Powell 1993, p. 80).
Unregulated trapping was a significant cause of severe population
declines, because fishers are easily trapped (Douglas and Strickland
1987, p. 523), and where trapping occurs, there is a potential for
populations to be negatively affected (Powell and Zielinski 1994, p.
64). Fisher populations can also be sensitive to the effects of
trapping because of a slow reproductive rate and the sensitivity of
population numbers to prey fluctuations (Powell and Zielinski 1994, p.
45). The presence of fishers is closely associated with the
availability of their prey. In general, fisher populations tend to be
distributed in small or isolated populations where their habitat or
prey distribution is fragmented naturally or by human actions. Fishers
in the USNRMs have some of the largest home ranges recorded for the
species (reviewed by Powell and Zielinski 1994, p. 58; IOSC 2010, p. 4;
reviewed by Lofroth et al. 2010, p. 68), possibly indicating a
fragmented, suboptimal landscape typical of peripheral populations, and
consequently small populations. Small or isolated populations may be
more intensely affected by the additional mortality from furbearer
harvest than are more robust and widespread populations if harvest is
not adequately regulated (Powell and Zielinski 1994, pp. 45, 66). There
is also the potential for fisher populations to be seriously affected
by unintended trapping or incidental trapping for other species,
including other furbearers (Powell and Zielinski 1994, p. 45).
Fishers are classified as furbearers under State codes in both
Idaho and Montana (IDFG 2010, p. 35; MTFWP 2010, Attachment 10, p. 2).
The fisher also is considered a species of greatest conservation need
in Idaho. Other furbearer species are legally trapped in the State, but
trapping seasons for fishers have been closed for over 60 years in
Idaho (IOSC 2010, p. 12). Fishers are legally trapped in Montana. The
authority to regulate trapping procedures resides with the States'
respective fish and wildlife or game commissions (Idaho Administrative
Code 13.01.16; Montana Code Annotated 2009b), which review and revise
furbearer trapping regulations every 2 years-most recently for the 2010
to 2012 seasons in Idaho (IDFG 2010, entire) and the 2010 and 2011
seasons in Montana (MTFWP 2010, Attachment 10, p. 2). The 2-year rules
review period has been in effect since at least 1986 in Idaho and since
2006 in Montana (MTFWP 2007, p. 2; White 2011c, pers. comm.). Within
this 2-year period, game commissions and State wildlife agencies have
authority to close seasons, change season lengths, adjust or implement
quotas, and apply other means to reduce impacts to intentionally or
incidentally trapped populations, if it is considered necessary (White
2011b, pers. comm.; Idaho Administrative Code 2010, 13.01.16; MTFWP
2010, Attachment 10, p. 7). Based on the current trapping regulations,
fisher will not be targeted, but legal trapping will occur for other
species during the 2-year period in
[[Page 38525]]
Idaho, and legal trapping for fishers will be subject to the
established regulations and authority in Montana (see Factor D section
below).
Most of the population distribution information for Montana is
based on specimens from the regulated furbearer trapping program
started in 1979 (MTFWP 2010, p. 2, Attachment 4, entire; MTNHP 2010b,
entire). There are 305 specimens, from legal harvest or mortality
incidental to legal harvest for other species, recorded in MTFWP files
since 1968 (Vinkey 2003, p. 51; MTFWP 2010, p. 2). Harvest over the
past 27 years has been most productive in Trapping District 2, which
includes the 200-km (125-mi) long Bitterroot Divide with Idaho (MTNHP
2010b, entire), and trapping in Montana over the past 8 years has been
conducted in this area almost exclusively (MTFWP 2010, Attachment 3,
entire). The Bitterroot Divide area in west-central Montana is a
strong-hold for fishers of native lineage that form a population with
fishers in Idaho (Schwartz 2007, p. 924). Trapping District 2 has a
five fisher quota, which is filled most years (MTFWP 2010, Attachment
8, pp. 1, 4). Harvest or other factors may be impacting the fishers in
Trapping District 1, including the Cabinet Mountains, in the northwest
corner of the State. The trapping quota has been reduced from 10 to 2
between 1993 and 1996, and harvest is low and variable (MTFWP 2010,
Attachment 8, p. 1). A low harvest level could reflect low trapper
effort, difficult access, variability in prey availability, or a small
or difficult to detect population. Six of the eight individuals
captured between 2003 and 2008 were adult (MTFWP 2010, Attachment 3,
entire), which suggests, but does not conclude, low recruitment. These
low harvest numbers are consistent with the scarcity of fisher
detections described in the evaluation of the Cabinet Mountain
reintroduction effort (Vinkey 2003, p. 33), and possibly indicative of
a population that is small or difficult to access.
There is disagreement among researchers as to whether trap
mortality is additive (operates in addition to) or compensatory
(compensates for) to natural mortality. Trapping is often the main
mortality factor for fisher (Krohn et al. 1994, pp. 139-140). Harvest
directed mainly at juveniles is most likely to be compensatory, as
juveniles have higher natural mortality than adults (Krohn et al. 1994,
p. 144). Numerous models are applied to managing harvest quotas to
sustain populations based on demographic rates, estimated fecundity,
population density, and spacing patterns (reviewed by Strickland 1994,
pp. 153-158; Koen et al. 2006, p. 1489). For example, low ratios of
juveniles to adult females in a harvest could be indicative of
declining populations (Strickland and Douglas 1981 in Koen et al. 2006,
p. 1484), which could be compensated for by altering harvest quotas in
succeeding years. In a single season, harvests take several hundred to
over a thousand individuals from many trapped populations across the
North American range of the species (Association of Wildlife Agencies
2010, entire), and statistical models can be applied to determine
population trends or changes in demographics. The small harvest in
Montana (from two to five individuals, depending on the trapping unit)
defies statistical analysis (Giddings 2010, pers. comm.), and the
evaluation of trapping effects is based strongly on demographics.
Juveniles are represented in the harvest over the past 10 years, and
the predominant portion of the harvest consisting of younger-aged males
is interpreted as an indication of light trapping pressure (MTFWP 2010,
Attachment 8, p. 4), which is likely compensatory to natural mortality.
Fishers have been caught incidentally to trapping for other
furbearers in Montana and Idaho. Montana records indicate 11 incidental
mortalities between 1983 and 2009, in addition to legally harvested
animals (MTFWP 2010, p. 4). Since 1970 in Idaho, 242 fishers were
trapped incidentally, 37 of those were reported as dead in the trap,
107 were released alive, and there were 98 trapper reports of fishers
captured but no indication of their condition (IOSC 2010, p. 12; White
2011b, pers. comm.). Incidental capture of fishers has progressively
increased between 2006 and 2010 in Idaho due to unknown reasons,
resulting in 22 of the 37 mortalities known to have occurred in the
past 40 years (White 2011b, pers. comm.). In addition, in the past 5
years, 42 live releases from traps and 37 captures of unknown status
also were reported (White 2011b, pers. comm.). The IDFG considers the
``unknown'' fishers to be live releases because it does not make sense
to report a capture and not a mortality due to the following
regulations: there is a legal requirement to report all fisher
captures, there is no penalty for incidental capture, it is illegal to
possess a killed fisher, and there is a small financial incentive to
surrender mortalities (White 2011c, pers. comm.). A change in the
number of ``unknowns'' reported between 2006 and 2008 to a similar
number of live releases in 2009 and 2010 corresponds with the start of
a highly publicized fisher habitat ecology project, and is indicative
of fur trappers' interest in contributing information for the study
(White 2011b, 2011c, pers. comm.).
Possible explanations of this recent rise in fisher captures
include, but are not limited to, population expansion or better
reporting and awareness, as stated above (IOSC 2010, pp. 12-13; White
2011b, pers. comm.). Over the past 40 years, Idaho incidental captures
exhibit a cyclic pattern of distinct highs and lows every 4 to 5 years,
which persist for 4 to 5 years. This pattern may reflect similar cyclic
changes in fisher population numbers that are unrelated to trapping
effects (White 2011b, pers. comm.). The level of incidental captures
demonstrated between 2006 and 2010 is the highest during the 40-year
reporting period. Combined with the increase in anecdotal sightings,
the recent high number of captures may be indicative of an increasing
and expanding population (White 2011b, 2011c, pers. comm.).
The number of trapping licenses sold doubled between 2001 and 2008
in Idaho (IDFG 2008, p. 8), which could mean additional trapping
pressure and an increased risk of unintended captures. Fishers are most
often caught incidentally to trapping for American marten (White 2011b,
pers. comm.). Although hundreds of martens are harvested most seasons,
the number of trappers targeting marten is comparatively low compared
to those targeting other species (IDFG 2007, p. 11; IDFG 2008, pp. 9-
11). Marten trapping efforts have remained steady in years with both
low and high incidental fisher capture (IDFG 2008, p. 10); therefore,
the total number of trapping licenses sold may not be a good indicator
of increased trapping pressure on fishers.
Both Montana and Idaho have a mandatory reporting requirement for
incidental mortality. Only Idaho requires reporting of animals trapped
and released. The fate of released animals is uncertain. Lewis and
Zielinski (1996, p. 295 and references therein) report that live
fishers are difficult to remove from traps, and suffer broken bones,
hemorrhage, self-mutilation, and predation as consequences of capture;
estimated survivability after release for incidentally captured fishers
is as low as 50 percent in some studies. There are no measures required
to avoid or prevent accidental capture of fishers in either Montana or
Idaho. Hence, additional mortality from incidental capture and release
may not be fully considered in management evaluations.
[[Page 38526]]
The known incidental capture mortality is less than one fisher per
year over the period of 1970 to 2005 in Idaho, and 1983 to 2009 in
Montana (MTFWP 2010, p. 4; White 2011b, pers. comm.). Additional
mortality from the trauma of capture and release and unreported
captures is likely, but quantification would be speculative. The
harvested population in west-central Montana is considered stable, with
the existing trapping pressure, including the reported incidental
mortality, based on consistent yearly harvest over time and the
continual presence of a high proportion of juveniles in the harvest
(MTFWP 2010, Appendix 8, p. 5). Relying on harvest statistics to assess
the status of the fisher population in the Cabinet Mountain region of
northwest Montana is not possible based on the lack of recent
incidental mortalities and limited harvest in the area (MTFWP 2010,
Appendix 8, p. 4; Appendix 11).
The impact of the reported level of unintentional mortality or
capture in Idaho is difficult to conclude based on the available
information. As stated above, the increase in captures in Idaho could
reflect an increase of trapper effort for other furbearers.
Alternatively, increasing captures may result from expanding or
increasing fisher populations and density-dependent displacement of
juveniles to less suitable habitats that increase their vulnerability
to capture. In addition, the number of reported live-released captures
could be misleading. Released fishers are not tagged or identified in
any way. Because fishers are easily trapped, it is possible that the
live-released data represent fewer individuals who are repetitively
captured. Individuals previously released could be represented in the
mortality data as well--a consequence of a later capture.
The recent increased mortality in Idaho may be compensatory to
natural forces, and thus not affecting population persistence. However,
without a history of demographic information (sex/age) of the affected
individuals, it is difficult to assess additive or compensatory
effects. Because demographic patterns are not available, we look to
other areas of the range where fisher populations are persisting with
sustainable, regulated harvest. Although factors affecting population
dynamics differ between the eastern and western U.S. populations,
fishers in peripheral populations and small geographic areas in the
east persist with regulated harvest far exceeding the targeted and
incidental harvest that occurs in both Montana and Idaho. For example:
during the 2001-2008 period, 30 to 108 fishers were harvested annually
in West Virginia, and the annual harvest in Rhode Island was as high as
97 individuals (Association of Fish and Wildlife Agencies 2010,
entire). Fishers have been legally harvested in Montana since 1983,
with the current Statewide quota in place since 1996, and are
considered stable at levels above the past 5-year mortality occurrence
in Idaho (MTFWP 2010, Attachment 8, p. 3). Mortality in Montana and
Idaho may be cumulative in areas of shared population, such as the
Bitterroot Mountains, but that impact cannot be concluded based on the
available information.
Recent incremental increases in incidental capture could be a
concern in Idaho if the trend continues and there is no evaluation or
consideration of the potential impacts to local and regional
populations. The available mortality and incidental capture data lack
context and could be interpreted in ways that reach a conclusion of
benign or detrimental effects. The IDFG is conducting a habitat ecology
study to assist in adjusting management to benefit fishers, with
results expected over the next 2 years (White 2011b, pers. comm.). By
studying fishers' habitat use, geographic or timing restrictions can be
crafted to limit their exposure to trapping for other species. We
anticipate that the resulting data will also be helpful in elucidating
the incidence and trends of fisher mortality in the USNRMs.
The role of overtrapping in reducing fisher populations is well
known. Trapping regulation, in addition to habitat regeneration and
population augmentations in some cases, have contributed to recovery
and persistence of fishers across the species range. Fishers are
legally trapped in Montana, but trapping seasons for fishers have been
closed for over 60 years in Idaho. The Montana fisher trapping program
began in 1983. After a period of adjustment, the current Statewide
quotas have been in place since 1996. Combined with a low level of
mortality incidental to trapping for other species, the Montana fisher
population is considered stable with the existing trapping pressure.
There is no trapping for fishers in Idaho, but a small number of
fishers have been captured or killed incidentally to the trapping of
other species--primarily the American marten--between 1970 and 2005.
The reported incidental capture and mortality increased between 2006
and 2010 for unknown reasons; possible explanations include an
increasing and expanding fisher population or greater exposure to
trapping or both. These recent incidental captures could be a concern
if the trend continues and there is no evaluation and consideration of
the potential impacts; however, efforts are ongoing to elucidate the
fisher's ecology and devise beneficial management strategies. The
potential exists for targeted or incidental trapping to negatively
impact fisher populations, but based on the available information, this
potential does not rise to the level of threat at this time.
Summary of Factor B
Trapping is considered one of the most important factors
influencing fisher populations, and unregulated overharvesting
contributed to the fishers' severe population decline in the early 20th
century. Targeted legal harvest occurs in Montana, and accidental
capture and mortality occur in both Montana and Idaho. If not
adequately regulated, low levels of harvest-related mortality, added to
natural mortality, have the potential to negatively impact small, local
populations. The Montana trapping season is monitored and regulated,
and there is no information to conclude that the distribution or
population numbers of fisher are being negatively impacted directly by
the current trapping regimes. Incremental increases in incidental
capture could be a concern in Idaho if the trend continues without some
evaluation of the local and regional population impacts, and
application of remedial actions, if necessary.
We conclude that the best scientific and commercial information
available indicates that the fisher in the USNRMs is not now, or in the
foreseeable future, threatened by overutilization for commercial,
recreational, scientific, or educational purposes to the extent that
listing under the Act as an endangered or threatened species is
warranted at this time.
Factor C. Disease or Predation
Mustelids are susceptible to viral-borne diseases, including
rabies, canine and feline distemper, and plague contracted through
contact with domesticated or wild animals (reviewed by Lofroth et al.
2010, pp. 65-66). Antibodies to a number of canine viruses have been
isolated from fishers in northwest California (Brown et al. 2008, p.
2). Parasitism by intestinal invertebrates (e.g., nematodes,
trematodes) is common (reviewed by Powell 1993, p. 72), and evidence of
other bacterial, protozoan, and arthropod disease agents also have been
identified in fishers (Banci 1989, p. v; Brown et al. 2008, p. 21).
Individuals weakened by parasitism or other
[[Page 38527]]
infectious disease processes may be more vulnerable to other sources of
mortality such as predation. However, little is known about the impacts
of disease in fishers, and there is no documentation of disease-causing
widespread population decline (Powell 1993, p. 71; Brown et al. 2008,
p. 5). There is no information on the incidence of disease specific to
fishers in the USNRMs.
Fox, bear, mountain lion, great-horned owls, and bobcat prey on
fishers, although there is little evidence to indicate that healthy
adult fishers have many natural enemies except humans (Douglas and
Strickland 1987, p. 516; Powell 1993, pp. 72-73). Forest fragmentation
that forces fishers to travel long distances without suitable hiding
cover may increase their vulnerability to predation by other carnivores
(Heinemeyer 1993, p. 26; Powell and Zielinski 1994, p. 62). Predation
of fishers newly translocated to Montana was reported (Roy 1991, pp.
29, 35; Heinemeyer 1993, p. 26), but this was attributed to the
relocation techniques used and fitness of the individual animals
(Powell and Zielinski 1994, p. 62; Vinkey 2003, p. 34). No information
is available regarding predation of fisher from established populations
in the USNRMs.
Summary of Factor C
There is little known about the impacts of disease in fishers, and
there is no information on the incidence of disease specific to fishers
in the USNRMs. There is no evidence that healthy adult fishers in
suitable habitat are subject to excessive rates of predation or that
fisher populations in the USNRMs are impacted by predation. We conclude
that the best scientific and commercial information available indicates
that the fisher in the USNRMs is not now, or in the foreseeable future,
threatened by disease or predation to the extent that listing under the
Act as an endangered or threatened species is warranted at this time.
Factor D. The Inadequacy of Existing Regulatory Mechanisms
To the extent that we identify possibly significant threats in the
other factors, we consider under this factor whether those threats are
adequately addressed by existing regulatory mechanisms. If a threat is
minor or the effects uncertain, listing may not be warranted even if
existing regulatory mechanisms provide little or no protection to
counter the threat. Numerous mechanisms affect land and species
management in the USNRMs. These mechanisms could include: (1) Local
land use laws, processes, and ordinances; (2) State laws and
regulations; and (3) Federal laws and regulations. Regulatory
mechanisms, if they exist, may preclude listing if such mechanisms are
judged to adequately address the threat to the species such that
listing is not warranted.
Seventy-two percent of the land area with forests typical of fisher
habitat types (fir, spruce, hemlock, Douglas fir (Jones and Garton
1994, p. 377-378)) in the USNRMs is managed by Federal entities within
national forest or park boundaries (USDA 2009, entire). Approximately
15,969 km\2\ (6,165 mi\2\) of wilderness areas are incorporated within
national forest boundaries. Private lands, including tribal and
commercial timber lands, comprise approximately 22 percent of fisher
forest types, and the remaining 6 percent is State or local government
forest (USDA 2009, entire). Fourteen national forests form large areas
of contiguous forested land area, often sharing boundaries with State
forest lands occupying lower elevations of intermountain valleys or
transition areas with woodlands or nonforested areas.
Federal Regulatory Mechanisms
National Forest Management Act
Federal activities on national forest lands are subject to the
National Forest Management Act of 1976 (NFMA) (16 U.S.C 1601-1614). The
NFMA requires the development and implementation of resource management
plans for each unit of the National Forest System. Implementation rules
for resource planning have undergone numerous revisions and legal
challenges. Planning rules amended in 2008 are being reevaluated, and
an amended 2000 planning rule is currently in place (74 FR 67059,
December 18, 2009). The 2000 planning rule emphasizes maintaining
ecological conditions that provide a high likelihood of supporting the
viability of native and desired nonnative species well distributed
throughout their ranges within a plan area. Ecological conditions need
to be maintained to support the natural distribution and abundance of a
species and not contribute to its extirpation.
Individual national forests may identify species of concern that
are significant to each forest's biodiversity. The fisher is considered
a sensitive species in the USFS Region 1 (western Montana and northern
Idaho) and Region 4 (central to southern Idaho) (USFS 2005, p. 4; USFS
2008, p. 6). A sensitive species is a species identified by a regional
forester for which viability is a concern (USFS Manual (2670.5). The
USFS' Sensitive Species Policy (USFS Manual (2670.32)) calls upon
national forests to assist and coordinate with States and other Federal
agencies in conserving species with viability concerns. Special
management emphasis is placed on Sensitive Species to ensure their
viability. The USFS is directed to develop and implement management
practices to ensure these species do not become endangered or
threatened. Management is in place at the individual forest plan level
or through regional direction that addresses habitat needs of fishers.
The habitat ecology of fishers in the region is not well studied, but
current management direction addresses forest characteristics known to
be important to fishers such as the protection of riparian areas,
retention of elements such as snags and downed woody material, size of
forest openings, and the retention of canopy cover (Samson 2006, pp.
15-16; Bush and Lundberg 2008, p. 16).
National Forests have been managing for old-growth forest since the
1990s, guided by regional standardized definitions and descriptors
(Green et al. 1992 Errata 2008, entire). The USFS planning regulations
require that forest plans identify certain species as Management
Indicator Species in order to estimate effects of management
alternatives on fish and wildlife populations (36 CFR 219.20). In
addition to Sensitive Species status, the fisher is considered a
Management Indicator Species by the Nez Perce and Flathead National
Forests to guide vegetation management of old-growth forest (USFS 1999,
p. 11; USFS 2006, p. 14). Vegetation objectives include maintaining or
actively restoring landscape composition, structure, and patterns to a
condition similar to that expected under natural disturbance and
succession regimes, and managing landscapes to develop larger old-
growth patch sizes, healthy riparian areas with mosaics of tree age and
size classes, and retention of structural elements such as snags and
down logs (USFS 1999, Appendix A; USFS 2006, pp. 41-42).
The habitat ecology of fishers in the region is not well studied,
but current management direction addresses forest characteristics known
to be important to fishers (USFS 1999, p. 24 and Appendix A; USFS
2003a, p. III-7; USFS 2003b, Appendix A; USFS 2006, pp. 41-42; Samson
2006, entire; Bush and Lundberg 2008, entire). Within the NFMA
regulatory framework, management direction and requisite monitoring,
forest management should be consistent with supporting fisher habitat
where natural ecological conditions allow. If each plan area
[[Page 38528]]
(national forest) supports a natural distribution and abundance, then
the large contiguous area of national forest lands comprising the
USNRMs would have the potential to support a regional population.
National Environmental Policy Act
As a sensitive species, the USFS is required to consider effects in
documentation completed under the National Environmental Policy Act
(NEPA) (42 U.S.C. 4321 et seq.). The NEPA requires Federal agencies to
consider the environmental impacts of their proposed actions and
reasonable alternatives to those actions. To meet this requirement,
Federal agencies conduct environmental reviews, including Environmental
Impact Statements and Environmental Assessments. The NEPA does not
itself regulate activities that might affect fishers, but it does
require full evaluation and disclosure of information regarding the
effects of contemplated Federal actions on sensitive species and their
habitats.
Healthy Forest Restoration Act
The Healthy Forest Restoration Act of 2003 (Pub. L. 108-148) (HFRA)
improves the capacity to conduct hazardous fuels reduction projects on
national forest lands to protect communities within or adjacent to USFS
boundaries (wildland-urban interface); municipal watersheds at risk
from fire; areas where windthrow or the existence or imminent risk of
an insect or disease epidemic significantly threatens ecosystem
components or resource values; and areas where wildland fire poses a
threat to threatened and endangered species or their habitat, or where
the natural fire regimes are important for their habitat.
Provisions of the HFRA can be used to expedite vegetation
treatment, such as mechanical thinning or prescribed fire, which could
be beneficial or detrimental to fishers on national forest lands. The
USFS and Department of the Interior revised their internal implementing
procedures describing categorical exclusions exempt from NEPA review to
expedite hazardous-fuels reduction and vegetation restoration projects
meeting certain criteria (68 FR 33813, June 5, 2003; 68 FR 44597, July
29, 2003).
The HFRA requires authorized projects, including categorical
exclusions under NEPA, to be planned and conducted consistent with
resource management plans and other relevant administrative policies,
such as the USFS' Sensitive Species Policy, and prohibits authorized
projects in wilderness areas, formal wilderness study areas, and other
restricted Federal lands (Section 102(d)). Projects conducted to reduce
fuels could provide a benefit to fishers by creating foraging habitat
if needed, promoting the growth of larger trees by decreasing
competition, and reducing catastrophic fire risk. While the reverse may
be true, the application of the Sensitive Species Policy should direct
HFRA projects to improve or maintain suitability of habitats for
fishers.
The Wilderness Act
The USFS manages 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. Lower-elevation forest in
wilderness areas may be important refuges for fishers because of
limited human access and less fragmentation than managed forests
(Hessburg et al. 2000, p. 78). For example: The Selway-Bitterroot
Wilderness in Idaho may have functioned as a refugium for native
fishers that enabled their survival through the severe population
decline in the past, and the area appears to be a stronghold for native
fishers today (Vinkey 2003, pp. 90-91).
National Park Service Organic Act
The National Park Service 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 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.'' Fishers or sign of fishers
have been reported in Glacier National Park in northern Montana, but
recent verified information is lacking. The Park's west side is a mix
of conifer forests, with maritime-influenced western hemlock and
western red cedar existing in ``ancient stands in places'' (NPS 2010,
entire), and likely capable of supporting fishers. The NPS does not
manage habitats specifically for fishers, but where fishers occur in
Glacier National Park, they and their habitats are protected from
large-scale loss or degradation due to the NPS' mandate to ``conserve
scenery * * * and wildlife [by leaving] them unimpaired.'' Due to the
limited access to exploitive activities such as timber or furbearer
harvest, National Parks, as with wilderness areas, may provide refuges
for fisher populations that are a source of individuals dispersing to
peripheral areas.
State Management
Montana
Regulatory mechanisms related to fisher conservation in Montana
apply to State forest and furbearer harvest management. Montana State
forests with fisher habitat types are situated in the northwest and
north-central part of the State, often sharing boundaries or
interspersed with national forest lands in lower elevations of
intermountain valleys. Timber harvest for revenue generation is
conducted on an annual basis and includes forest types preferred by
fishers; forests also are managed to promote a diversity of habitat
conditions beneficial to wildlife (MTDNRC 2010, p. 1). Fishers are
managed as a sensitive species ``primarily through managing for the
range of historically occurring conditions appropriate to the site''
(Administrative Rules of Montana (ARM) 2003, 36.11.436). In 2003,
MTDNRC formally codified mitigation measures specific to forest types
preferred by fisher for State forest management including: Timber and
salvage harvest, thinning, prescribed burning, road maintenance, and
other activities (ARM 2003, entire). Project-level evaluation
emphasizes large snag and coarse woody debris retention and emulation
of natural forest patch size and shape to maintain or contribute to
connectivity with crown canopy closure of greater than 39 percent and
patch greater than 91 m (300 ft) wide (ARM 2003, 36.11.403). Riparian
areas, within 100 ft of class-I (fish bearing) streams and 50 ft of
class-II (non-fish bearing) streams, maintain or are allowed to
progress to at least 40-percent canopy cover (ARM 2003, 36.11.440).
There is no specific direction to retain mature or larger trees for
fisher independent of snag retention, but it is stated that the
importance of late-successional riparian and upland forest shall be
considered in meeting the requirements for fishers (ARM 2003,
36.11.440).
The fisher is classified as a regulated furbearer in Montana (MTFWP
2010, Attachment 10, p. 2). Montana is the only State in the western
United States where fisher trapping is still legal. Trapping season is
open December 1 to February 15, or within 48 hours of a
[[Page 38529]]
quota being reached (MTFWP 2010, Attachment 10, p. 7). There is
authorization to close the season if conditions or circumstances
indicate a quota will be reached within 48 hours (MTFWP 2010,
Attachment 10, p. 7). Two districts are open for trapping--District 1
in the northwest has a quota of two, including the Cabinet Mountains,
and District 2 in west-central Montana, including the Bitterroot
Mountains, has a quota of five; there is a Statewide sub-quota of two
females (MTFWP 2010, Attachment 10, p. 7). Only one fisher may be taken
per person per season, and take must be reported within 24 hours to the
MTFWP (MTFWP 2010, Attachment 10, p. 7). Reporting and surrender of an
accidental mortality (unintended capture or outside legal season) must
be done within 24 hours of capture, and only uninjured animals can be
released from traps (MTFWP 2010, Attachment 10, p. 7). There are no
penalties for surrendering an accidentally killed fisher, but there are
penalties and fines for being in possession of an incidentally taken
fisher (MTFWP 2010, p. 4). There is no regulatory mechanism or
requirement in place to minimize incidental take of fisher.
Harvest quotas and seasons are evaluated and set by the MTFWP
Commission every year, with the general regulations established for 2-
year periods (Montana Code Annotated 2009b; MTFWP 2010, Attachment 10,
p. 2). Trends in harvest success, demographics (age class/sex), and
snow track surveys are used to determine the effectiveness of the quota
system and assist in the State's objective of maintaining current
fisher population size and distribution (MTFWP 2010, Attachment 8, pp.
1-3). A consistent harvest and the presence of juveniles are considered
an indication of a stable population (MTFWP 2010, pp. 1-2). Snow track
surveys are conducted along fixed routes in some areas of the State
that do not receive targeted fisher harvest (MTFWP 2010, Attachment 8,
p. 3); however, track surveys are conducted sporadically and are very
dependent on snow conditions for usefulness (Giddings 2010, pers.
comm.). Quotas have been adjusted downward several times since the
establishment of the regulated trapping program in1983 in response to
harvest success, demographics of harvested animals, and track survey
data. Quotas and harvest have been relatively consistent since 1996
(MTFWP 2010, Attachment 8, pp. 1, 3). We are not aware of any
established objectives or direction that indicates action thresholds
for adjusting quotas or practices.
Idaho
The fisher is identified as a species of greatest conservation need
in the Idaho Comprehensive Wildlife Conservation Strategy, which
recommends actions to determine fisher population trends, landscape and
regional scale response to habitat disturbance, genetic composition of
populations, and the relationship between habitat fragmentation and
movement patterns (IDFG 2005, p. 365, Appendix B, p. 8). Species of
greatest conservation need are those considered at high risk due to low
number, declining numbers, or other factors that make them vulnerable
to extirpation (IDFG 2005, Appendix B, pp. 1, 8). There are no
identified regulatory mechanisms that apply to habitat management for
fisher in the State.
Implementing rules that protect riparian areas from timber harvest
actions for the Idaho Forest Practices Act apply to operations on lands
under all management types. Management goals for class I streams
include the retention of standing conifers, hardwoods and snags within
15 m (50 ft) on each side, leaving 75 percent of existing shade, and
within 9 m (30 ft) on each side of class II streams (Idaho
Administrative Code 2000, 20.02.01).
The fisher is legally classified as a furbearer in Idaho, but no
legal season has been open for over 60 years (Idaho Administrative Code
2010, 13.01.16; IOSC 2010, p. 11). Capture of fishers has occurred,
primarily incidentally to legally trapped marten during the open season
from November 1 through January 31 (White 2011a, pers. comm.). There
are no legislated regulatory mechanisms in place to minimize incidental
take of fisher, but voluntary trapper education is provided to help
direct trapping towards the intended species (White 2011a, pers.
comm.). Marten and other furbearer trapping is conducted under
Statewide licensure but management occurs at smaller, regional levels.
There is no limit to the number of Statewide licenses sold, and no
seasonal quotas for marten are in place (White 2011b, pers. comm.). The
IDFG Commission has the authority to set bag or possession limits and
seasons (Idaho Administrative Code 2010, 13.01.16). A mandatory
furtaker harvest report is required to be submitted to the IDFG by July
31 to assist with setting season limits (IDFG 2010, p. 38). An
incidental capture of a fisher that results in mortality requires
reporting and surrender of the carcass to IDFG within 72 hours; live
animals require immediate release if they appear unharmed or, if
animals appear injured, the IDFG is contacted for assistance (IDFG
2010, p. 36). Trappers are reimbursed $10 for the surrendered carcass
and are required to report the capture, dead or released alive, on the
harvest report. We are not aware of a mechanism in place to adjust a
trapping season while in session, such as closing a unit or area early,
to accommodate an incidental take of a fisher or fishers. We have no
knowledge of how the reports of incidental take of a fisher or fishers
are used to adjust subsequent marten seasons or quotas, or those of
other target species that fisher could be caught incidentally to, in
order to avoid additional mortality.
Management on National Forests and State Forests for Other Species
Benefitting Fisher
All national forests in the USNRMs have amended their forest plans
with the Northern Rockies Lynx Management Direction to provide
protections and conservation for the Canada lynx (USDA 2007, entire).
Lynx utilize mesic coniferous forests although their range extends to
higher elevation zones than fishers (reviewed by Ruediger et al. 2000,
p. 1-3). Lynx similarly prefer to move through continuous forest cover,
frequently use riparian zones, and target snowshoe hare as a principle
prey species (reviewed by Ruediger et al. 2000, pp. 1-4, 1-7). Large
woody debris within mature or older conifer or mixed-conifer sites are
selected by female lynx for denning, and these elements are known to be
used by fishers (Jones and Garton 1994, p. 380; reviewed by Ruediger et
al. 2000, p. 1-4; reviewed by Lofroth et al. 2010, p. 106). Direction
is in place for national forest lands to provide connectivity for lynx
travel throughout the USNRMs (USDA 2007, p. 27). Standards and
guidelines for specific habitat protections are applied in the north
half of the USNRMs, where habitats are known to be occupied by lynx
(USDA 2007, p. 29). Specific measures are applied at the scale of a
female lynx's home range, which is similar to home range sizes reported
for fisher in the USNRMs and British Columbia (reviewed by Ruediger et
al. 2000, p. 6-2; reviewed by Lofroth et al. 2010, p. 68). These
measures include limiting disturbance by timber harvest and other
activities, maintaining patches conducive to denning and retention of
coarse woody debris, protecting regenerating areas that provide
snowshoe hare habitat, and retaining wooded areas (USDA 2007, pp. 8-
28).
In 1998, the Service issued a biological opinion on the
[[Page 38530]]
implementation of USFS Land and Resource Management Plans as amended by
the Interim Strategy for Managing Fish-Producing Watersheds in Eastern
Oregon and Washington, Idaho, Western Montana, and Portions of Nevada
(INFISH) (Service 1998, entire). The guidelines, developed to protect
bull trout and other fish habitat, also may provide benefits to fisher
by protecting riparian corridors, establishing large woody debris
requirements, and delineating Riparian Habitat Conservation Areas which
would prohibit timber harvest in most situations. Conservation Areas
would be established within 91 m (300 ft) slope distance of either side
of class I streams, to 46 m (150 ft) on both sides of perennial class
II streams, and within 15 to 30 m (50 to 100 ft) of seasonal or
intermittent streams and small wetlands (Service 1998, p. 9).
The USNRMs covers an area that includes all or part of the Northern
Continental Divide, Selway-Bitterroot, Selkirks, and Cabinet-Yaak
Grizzly Bear Recovery Zones. Fishers may benefit from the reduction of
road densities or reduced motorized use of roads on national forest
lands or the large areas of core habitat within 3rd and 4th order
watersheds with no motorized travel routes or high use trails within
the recovery zones (Interagency Grizzly Bear Committee 1998, entire).
Management direction intended to protect other species listed under
the Endangered Species Act could provide benefit to fishers on Montana
State forests. Montana State forests located in the Cabinet-Yaak and
Northern Continental Divide Recovery Zones for the threatened grizzly
bear are managed to limit road density and maintain hiding cover near
roads and adjacent to riparian areas (ARM 2003, 36.11.432-433).
Retention of coarse woody debris, vegetative cover for landscape
connectivity, and habitat for a common prey species--snowshoe hare--are
intended to contribute to Canada lynx (Lynx Canadensis) habitat
requirements (ARM 2003, 36.11.435). The retention of vegetation and
minimization of disturbance in riparian areas to protect bull trout
habitat also could benefit fisher on State forest land.
Summary of Factor D
In our review of the factors affecting fishers in the USNRMs, we
found no single factor or accumulated effects of factors that, when
considered within the foreseeable future, rose to a level significant
enough to warrant the protections of the Act. There is a concern
regarding the adequate control of mortality due to capture incidental
to the trapping of other furbearing animals. The authority exists under
States' laws to manage trapping programs, specifically for fisher, as
well as other species. However, we are unaware of any policy or
management direction that would invoke that authority and apply
adaptive management or minimization measures to reduce additional
mortality from unintended harvest. Since we did not consider that the
threat of incidental mortality, based on the limited information
available to us, rose to the level of a threat to the species in the
foreseeable future, it is not necessary to consider the effectiveness
of the relative regulatory mechanism.
We conclude that the best scientific and commercial information
available indicates that the fisher in the USNRMs is not now, or in the
foreseeable future, threatened by the inadequacy of existing regulatory
mechanisms to the extent that listing under the Act as an endangered or
threatened species is warranted at this time. It is unclear that
regulatory mechanisms in addition to those described are needed for the
species based on the current understanding of threats.
Factor E. Other Natural or Manmade Factors Affecting Its Continued
Existence
Population Size and Isolation
A principle of conservation biology is that small, isolated
populations are subject to an increased risk of extinction from
stochastic (random) environmental, genetic, or demographic events
(Brewer 1994, p. 616). Environmental changes such as drought, fire or
storms have severe consequences if affected populations are small and
clumped together (Brewer 1994, p. 616). Loss of genetic diversity can
lead to inbreeding depression and an increased risk of extinction
(Allendorf and Luikart 2007, pp. 338-343). Demographic changes can
reduce the effective population size (number of breeding individuals).
Populations with small effective size show reductions in population
growth rates, loss of genetic variability, and increases in extinction
probabilities (Leberg 1990, p. 194; Jimenez et al. 1994, p. 272;
Allendorf and Luikart 2007, pp. 338-339).
There is little information to indicate fisher population numbers
or population dynamics in the USNRMs. Fishers are vulnerable to the
effects of small populations and isolation based on characteristics of
their life history. Fishers are known to be solitary and territorial,
and require large home ranges where landscapes are less than optimal
(Weir and Corbould 2010, p. 405). This results in low population
densities, as the population requires a large amount of quality habitat
for survival and proliferation. Fishers also are long-lived, have low
reproduction rates, and, though capable of long-distance movements,
generally have small dispersal distances. Small dispersal distances may
be a factor of fishers' reluctance to move through areas with no cover
(Buskirk and Powell 1994, p. 286). Thus, where habitat is fragmented it
is more difficult to locate and occupy distant yet suitable habitat,
and fishers may be aggregated into smaller interrelated groups on the
landscape (Carroll et al. 2001, p. 974).
Territoriality and habitat specificity compounded by habitat
fragmentation may contribute to the strong genetic structuring over
intermediate geographic distances seen in fisher populations in other
parts of the species' range (Kyle et al. 2001, p. 2345; Wisely et al.
2004, pp. 644, 646). Higher levels of genetic structuring describe
populations that are more genetically distinct and have less
intrapopulation variation, a condition occurring in peripheral or more
disturbed habitats of a species' range with low effective population
sizes and limited genetic exchange (Kyle and Strobeck 2001, p. 343).
Where these conditions exist, species face an increased vulnerability
to extinction (Wisely et al. 2004, p. 646).
Small, isolated populations can be at risk from stochastic factors.
Demographic stochasticity (the chance events associated with annual
survival and reproduction) and environmental stochasticity (temporal
fluctuations in environment conditions) tend to reduce population
persistence (Shaffer 1981, p. 131). Combinations of factors can
interact to increase the risk of extinction. Trapping pressure, for
example, if additive to natural mortality, could act by itself or in
combination with environmental conditions to have significant impact on
annual survival. Regional fires that have occurred historically in the
USNRMs could reduce the suitability of large forest tracts for decades,
reducing habitat and further isolating small populations.
As stated above, we have little information to indicate the number
of individuals, population dynamics, or evidence of genetic structuring
and inbreeding for fishers in the USNRMs. Although we have no
information on fisher abundance, their home range sizes are large--an
indication that the availability of resources may be limiting
population size. Their restricted geographic range, based on isolation
from larger populations in Canada or the United States, frequently
correlates with
[[Page 38531]]
small population size (Purvis et al. 2000, p. 1947). Given the
restricted distribution, the presumably small population size, and
propensity to aggregate on the landscape, fishers in the USNRMs are
vulnerable to demographic, environmental, and genetic stochasticity,
which could impact long-term persistence. The USNRMs fisher population
resurged from near extirpation in the 1920s with possible assistance
from augmentations. It is likely that the historical populations were
never large. Fishers' response to the impacts of a changing landscape
from human development and timber harvest are uncertain. The species
appears to have several characteristics related to small population
size that increase the species' vulnerability to extinction from
stochastic events and other threats on the landscape. Currently, we do
not have sufficient information on these environmental or anthropogenic
threats to know whether they affect small populations to an extent that
threatens the fisher in the USNRMs. We are unable to quantify a
foreseeable future for stochastic events that may have disproportionate
negative effects on small population sizes. We do not anticipate the
effects of these events on small population size to change, but our
understanding of these effects may improve over time.
Summary of Factor E
Based on the best available information, we have no indication that
other natural or anthropogenic factors are likely to significantly
threaten the existence of the fisher in the USNRMs. We recognize the
inherent vulnerabilities of small populations and restricted geographic
range. The impacts of various potential threats can be more pronounced
on small or isolated populations, and we have identified numerous
potential threats occurring on the landscape within the range of the
fisher in the USNRMs (see Factor A and B section). However, at this
time we do not have information to indicate that these activities pose
a threat to the fisher. Additionally, we do not consider a small
population alone to be a threat to species; rather, it can be a
vulnerability that can make it more susceptible to threat factors, if
they are present.
We conclude that the best scientific and commercial information
available indicates that the fisher in the USNRMs is not now, or in the
foreseeable future, threatened by other natural or anthropogenic
factors affecting its continued existence, or that these factors act
cumulatively with other potential threats, to the extent that listing
under the Act as an endangered or threatened species is warranted at
this time.
Finding--Determination of Status of Distinct Population Segment
As required by the Act, we considered the five factors in assessing
whether the fisher in the USNRMs is endangered or threatened throughout
all or a significant portion of its range. We have carefully examined
the best scientific and commercial information available regarding the
status and the past, present, and future threats faced by the fisher in
the USNRMs. We reviewed the petition, information available in our
files, and other published and unpublished information submitted to us
by the public following our 90-day petition finding. We also consulted
with fisher experts and other Federal and State resource agencies. We
were able to qualitatively describe a foreseeable future for forest
management, development, and climate change and discussed how we
anticipate each factor to change over time. We were unable to project
specific changes to the species from these foreseeable actions into the
future because we do not have sufficient data to know how the analyzed
factors will affect the species.
The fisher is a forest-dependent species that evolved in the USNRMs
in a complex landscape mosaic shaped by climate driven events such as
fire, drought, and forest diseases. Fisher populations were greatly
reduced to the point they were believed extirpated in the USNRMs in the
early 20th century due to unregulated overharvest and indiscriminate
predator control. Although current comprehensive fisher population
numbers and trends are not known, fisher populations have resurged from
previous lows concurrently with the effects of human development and
timber harvest and the regulation of harvest. The USNRMs landscape
supports fisher, but it is unknown if the system has the capacity to
support a population long term. Interpreting or projecting the impacts
of forest management, development, and resource extraction is
complicated by a lack of knowledge of fisher habitat ecology in the
region, and mixed reports of how fishers respond to human disturbance.
Fisher habitats could be vulnerable to the climate change effects of
increased temperature and earlier spring snowmelt predicted to produce
longer fire seasons. An increase in incidence of forest diseases or
novel diseases also could accompany a changing climate. Although the
potential for changing fire and disease regimes exists, these events
are dependent on complex patterns of moisture availability and cannot
be predicted with confidence.
Targeted legal harvest of fishers occurs in Montana and accidental
capture and mortality occurs in both Montana and Idaho. Low levels of
additional mortality from harvest to natural mortality have the
potential to negatively impact small, local populations if not
adequately regulated. There is no indication that the distribution or
population numbers of fisher are being negatively impacted directly by
the current trapping regimes in Montana. Recent increases in incidental
capture and associated mortality could be a concern in Idaho if the
trend continues without some evaluation of the local and regional
population impacts and remedial actions applied, if necessary.
A restricted geographic range like the fisher's in the USNRMs
frequently correlates with small population size, and it is likely that
the historical populations were never large. Given the restricted
distribution, the presumably small population size, and propensity to
aggregate on the landscape, fishers in the USNRMs are vulnerable to
extinction from stochastic events and other threats on the landscape
which could impact long-term persistence. Fishers' response to the
impacts of a changing landscape from human development, timber harvest
and climate change are uncertain. As stated above, trapping pressure,
if additive to natural mortality, could act by itself or in combination
with environmental conditions to have significant impact on annual
survival. Currently, we do not have information on these threats to an
extent that allows us to know whether small population size allows for
other environmental or anthropogenic factors to create a threat to the
fisher in the USNRMs.
Our review of the best available scientific and commercial
information pertaining to the five factors does not support the
assertion that there are threats of sufficient imminence, intensity, or
magnitude to indicate that the fisher in the USNRMs is in danger of
extinction (endangered) within the foreseeable future (threatened),
throughout all or significant portion of its range. Therefore, we find
that listing the fisher in USNRMs throughout its range as an endangered
or threatened species is not warranted at this time.
In making this finding, we recognize that the fisher in the USNRMs,
despite not being warranted for listing as endangered or threatened,
may benefit from increased management emphasis
[[Page 38532]]
due to its need for forest cover and susceptibility to capture and
mortality from furbearer harvest. We recommend precautionary measures
to protect the species be continued where they are in place and
expanded where they are not. We recommend and encourage additional
research to improve the understanding of the species, so that our
responses to future potential threats can be better understood.
Significant Portion of the Range
Having determined that the fisher in the USNRMs is not in danger of
extinction or likely to become so within the foreseeable future
throughout all of its range, we must next consider whether there are
any significant portions of the range where the fisher in the USNRMs is
in danger of extinction or is likely to become endangered in the
foreseeable future.
The Act defines an endangered species as one ``in danger of
extinction throughout all or a significant portion of its range,'' and
a threatened species as one ``likely to become an endangered species
within the foreseeable future throughout all or a significant portion
of its range.'' The term ``significant portion of its range'' is not
defined by the statute. For the purposes of this finding, a portion of
a species' range (fisher in the USNRMs) is ``significant'' if it is
part of the current range of the species, and it provides a crucial
contribution to the representation, resiliency, or redundancy of the
species. For the contribution to be crucial it must be at a level such
that, without that portion, the species would be in danger of
extinction.
In determining whether a species is threatened or endangered in a
significant portion of its range, we first identify any portions of the
range of the species that warrant further consideration. The range of a
species can theoretically be divided into portions in an infinite
number of ways. However, there is no purpose to analyzing portions of
the range that are not reasonably likely to be significant and
threatened or endangered. To identify only those portions that warrant
further consideration, we determine whether there is substantial
information indicating that: (1) The portions may be significant, and
(2) the species may be in danger of extinction there or likely to
become so within the foreseeable future. In practice, a key part of
this analysis is whether the threats are geographically concentrated in
some way. If the threats to the species are essentially uniform
throughout its range, no portion is likely to warrant further
consideration. Moreover, if any concentration of threats applies only
to portions of the species' range that clearly would not meet the
biologically based definition of ``significant'' (i.e., the loss of
that portion clearly would not reasonably be expected to increase the
vulnerability to extinction of the entire species to the point that the
species would then be in danger of extinction), such portions will not
warrant further consideration.
If we identify portions that warrant further consideration, we then
determine their status (i.e., whether in fact the species is endangered
or threatened in a significant portion of its range). Depending on the
biology of the species, its range, and the threats it faces, it might
be more efficient for us to address either the ``significant'' question
first, or the status question first. Thus, if we determine that a
portion of the range is not ``significant,'' we do not need to
determine whether the species is endangered or threatened there; if we
determine that the species is not endangered or threatened in a portion
of its range, we do not need to determine if that portion is
``significant.''
Applying the process described above for determining whether a
species is threatened in a significant portion of its range, we
considered status first to determine if any threats or potential
threats acting individually or collectively threaten or endanger the
species in a portion of its range. We have analyzed the threats to the
degree possible, and determined they are essentially uniform throughout
the species' range. The limited information available for the fisher,
such as the lack of population numbers and dynamics, and an incomplete
knowledge of tolerances to disturbance and habitat needs, does not
allow us to determine what portion of the range if any, would be
impacted to a significant degree more than any other.
Conclusion of 12-Month Finding
We do not find that the fisher in the USNRMs is in danger of
extinction now, nor is it likely to become endangered within the
foreseeable future, throughout all or a significant portion of its
range. Therefore, listing the species as endangered or threatened under
the Act is not warranted at this time.
We request that you submit any new information concerning the
status of, or threats to, the fisher in the USNRMs to our Montana
Ecological Services Field Office (see ADDRESSES section) whenever it
becomes available. New information will help us monitor this species
and encourage its conservation. If an emergency situation develops for
the fisher in the USNRMs or any other species, we will act to provide
immediate protection.
References Cited
A complete list of references cited is available on the Internet at
http://www.regulations.gov and upon request from the Montana Ecological
Services Field Office (see ADDRESSES section above).
Author
The primary author of this document is staff of the Montana
Ecological Services Field Office (see FOR FURTHER INFORMATION CONTACT
section above).
Authority
The authority for this action is the Endangered Species Act of
1973, as amended (16 U.S.C. 1531 et seq.).
June 14, 2011.
Gabriela Chavarria,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. 2011-16349 Filed 6-29-11; 8:45 am]
BILLING CODE 4310-55-P