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The west coast population of the fisher was accorded federal
candidate status in April 2004.
The state of Oregon lists the fisher as a sensitive
species.
Historic
Status and Current Trends
Fishers, found only in North America, occur in the northern coniferous
and the mixed forests of Canada and the northern United States.
Their range extends from the mountainous areas in the southern
Yukon and Labrador Provinces southward to central California and
Wyoming, the Great Lakes and Appalachian regions, and New England.
In Oregon, fishers occurred historically throughout the Coastal
and Cascade mountains. Currently, the range of the fisher is severely
reduced. Despite extensive surveys conducted in forested regions
of Oregon, records dating from 1954 to 2001 show that the remaining
populations of fishers are restricted to two separate and genetically
isolated populations in southwestern Oregon; one in the northern
Siskiyou Mountains and one in the southern Cascade Range. The
population in the southern Cascades descended from reintroduced
fishers that were translocated to Oregon from British Columbia
and Minnesota.
Description
and Life History
The fisher, a member of the weasel family (Mustelidae), has
a long body, short legs and a long, bushy tail. The head
is broad and flat with a sharp, pronounced muzzle. The ears are
broad, rounded, and low. Fur color varies from light brown to
dark blackish brown, although the face, neck, and shoulders may
have a lighter grizzled gray appearance. Often there are irregular
white patches on the chest and underside. Fur length ranges from
30 millimeters (about 1 inch) on the stomach and chest to 70 millimeters
(about 2.75 inches) on the back. Adults range in length from 90
to 120 centimeters (about 2.5 to 4 feet). Males weigh 3 to 6 kilograms
(about 7 to 13 pounds); females weight 1.5 to 2.5 kilograms (about
3 to 5.5 pounds). Large feet, with 5 toes on all 4 feet and retractable
claws, enable fishers to rotate their hind paws almost 180 degrees,
allowing them to run down trees head first like a squirrel. Central
pads on the hind paws have circular patches of coarse hair which
are associated with plantar glands. These glands produce a distinctive
odor believed to be used for communication during reproduction.
It is estimated that fishers live up to 10 years. They are solitary
animals except during the breeding season (late February through
April).
Fishers are opportunistic predators that hunt exclusively in
forested habitats where prey is abundant and vulnerable to capture.
Their diverse diet includes birds, porcupines, snowshoe hare,
squirrels, mice, shrews, voles, reptiles, insects, carrion, vegetation,
and fruit. Their name is misleading since fishers do not actually
catch fish. The name may have come from early European settlers
who noted the fisher's similarity to the European polecat which
was variously known as a fitchet or fitchew.
Habitat
Fishers select forests with high canopy closure, large trees,
and a high percentage of conifers. The physical structure of this
type of forest provides the fisher with reduced vulnerability
to predation and an abundance of prey. The distribution of the
fisher is likely limited by elevation and snow depth.
Reasons for Decline
The west coast population of the fisher is endangered mainly
because of loss and fragmentation of habitat due to timber harvest,
roads, urban development, recreation, and wildfires. Other threats
include small population sizes and isolation, predation, and human-caused
mortality from vehicle collisions, poaching, and incidental capture
and injury.
Conservation Measures
In December 2000, the U.S. Fish and Wildlife Service (USFWS) received
a petition to list the west coast population of the fisher as
an endangered species in Washington, Oregon, and California. The
USFWS concluded that the west coast fisher population was a distinct
population segement and was warranted for listing but precluded
by other higher priority listing actions. Therefore, the USFWS placed
the species on the federal list of candidates and, after conducting
an annual review of the species status, may propose to list
the species at a later date. We encourage state and federal agencies
proposing activities within the historic range of the fisher to
give consideration to the fisher during the environmental planning
process, especially activities which alter or destroy mature and
old growth forests.
References and Links
Aubry, K. B., Lewis, J. C. 2003. Extirpation and reintroduction
of the fisher (Martes pennanti) in Oregon: implications for their
conservation in the Pacific states. Biological
Conservation 114 (1):79-90.
Powell, R.A. and W.J. Zielinski. 1994. Fisher. In: Ruggiero,
L. F, Aubry, K B, Buskirk, SW, Lyon L.J., and Zielinski, W. J.
eds. American marten, fisher, lynx, and wolverine. Gen. Tech.
Rep. RM-254. Fort Collins, CO. Rocky Mountain Forest and Range
Experiment Station, Forest Service, U.S. Department of Agriculture;
184 p.
U.S. Fish and Wildlife Service. 1996. Endangered and threatened
wildlife and plants; 90-day finding for a petition of list the
fisher in the western United States as threatened. FR
61:8016-8018.
U.S. Fish and Wildlife Service. 2003. Endangered and threatened
wildlife and plants; 90- day finding for a petition to list a
distinct population segment of the fisher in its west coast range
as endangered and to designate critical habitat. FR
68:41169-41174
U.S. Fish and Wildlife Service. 2004. Endangered and Threatened
Wildlife and Plants; 12-month
Finding for a Petition to List the
West Coast Distinct Population Segment of the Fisher (Martes
pennanti).
Portland,
Washington Department of Fish and Wildlife Final
Report 1998.
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