Endangered Species | Mammals
Mountain-Prairie Region
Graphic button showing the 8 state mountain prairie region

Fisher

 

Jump to a section: Diet and breeding | Recent actions & links | « Back to mammals | Open / close all

  • Fisher. Credit: USFWS.

    Fisher. Credit: USFWS.

Fisher (Pekania pennanti)

Species description: The fisher (Pekania pennanti) is a medium-sized mammal native to North America.  It is classified in the order Carnivora, family Mustelidae – a family that also includes weasels, mink, martens, and otters. 

Adult fishers are light brown to dark blackish-brown, with the face, neck, and shoulders sometimes being slightly gray.  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 35 to 47 inches, and weigh 6.6 to 13.2 pounds.  Females range from 29 to 37 inches in length and weigh 3.3 to 5.5 pounds.

Location: Fishers are found across Canada and in four areas of the United States – New England, Great Lakes, Northern Rocky Mountains (NRM), and the Pacific Northwest.  In the NRM, fishers are distributed in northwest and west-central Montana and northern and north-central Idaho.  Verified records indicate the current distribution of fishers in the NRM is similar to their historic distribution.

Habitat: Fishers habitat includes low- to mid-elevation environments of mesic (moderately moist), coniferous and mixed conifer forests.  Within these forests, fishers are associated more commonly with landscapes that are greater than 50 percent mature forest, arranged in a contiguous, complex mosaic.  At smaller spatial scales, fishers appear to select for intermediate abundance of habitat edges, high canopy cover, large trees, and tree cavities.


Diet and breeding »

« Back to the top

Diet:Fishers are opportunistic predators primarily of snowshoe hares, squirrels, mice, and birds.  Carrion and plant material (e.g., berries) also are consumed.  The fisher is one of the few predators that kills porcupines, and porcupine remains have been found more often in the gastrointestinal tract and scat of fisher than any other predator.  As dietary generalists, fishers tend to forage in areas where prey is both abundant and vulnerable to capture. 

Breeding: Fishers are solitary except during the breeding season, which is generally from late February to the middle of May in the NRM.  Litter sizes for fishers range from one to six with a mean of two to three kits.  New born kits are entirely dependent and may nurse for 10 weeks or more after birth.  Kits develop their own home ranges by one year of age. 

 


Recent actions & links »

« Back to the top

Recent Actions: October 2017: In 2016, the Service published a 90-day finding that announced there was substantial information that listing the NRM fisher may be warranted. Based on the best scientific and commercial information available, the Service found that the NRM fisher is genetically different from other fisher populations and qualifies as a distinct population segment under the ESA.

2017: In response to the substantial 90-day finding, the Service prepared a Species Status Assessment report, which is a stand-alone science-based report that provides foundational biological information, articulates key uncertainties, and characterizes the species’ current and future condition and viability under various scenarios and timeframes.

2017: Using the Species Status Assessment as the foundation, the Service published a not warranted 12-month finding in October.

2016: In response to the petition, the Service published a substantial 90-day finding, indicating there was substantial information that listing may be warranted due to non-target poisoning and trapping.

 2013:  The Northern Rockies fisher was most recently petitioned for listing under the Endangered Species Act.

 June 2011:  The Fish and Wildlife Service completed a status review of the fisher in the U.S. Northern Rocky Mountains, and concluded it does not warrant protection under the Endangered Species Act in Idaho, Montana, or Wyoming. 

We analyzed potential factors that may affect the habitat and range of the fisher in the U.S. Northern Rocky Mountains including timber harvest and management, climate change, fire, forest disease, furbearer trapping, disease and predator relationships, inadequacy of existing regulatory mechanisms, and the effects of small population size.  We concluded that these potential factors do not significantly impact the species.

Even though the species will not be protected under the Endangered Species Act, we recognize that the fisher in the Northern Rockies may benefit from increased management emphasis due to its need for forest cover and its susceptibility to capture and mortality from furbearer harvest. We recommend and encourage additional research to improve the understanding of the species and precautionary measures to protect the species.

To assist in monitoring the fisher in the U.S. Northern Rockies, we ask the public to submit any new information on the fisher’s status or impacts. Please submit your comments to the U.S. Fish and Wildlife Service, Montana Ecological Services Field Office, 585 Shepard Way, Helena, MT 59601.


The U.S. Fish and Wildlife Service recently determined that the Northern Rocky Mountain distinct population of the fisher may warrant federal protection as a threatened or endangered species. The Northern Rocky Mountain population area includes portions of northern Idaho, western Montana, and northwestern Wyoming.

The Service will undertake a more thorough review of the fisher to determine if adding the species in the Northern Rocky Mountains to the federal list of threatened and endangered wildlife and plants is warranted.

More information can be found at the Service's ECOS webpage

 

The mission of the U.S. Fish and Wildlife Service is working with Others to conserve, protect, and enhance fish, wildlife, plants and their habitats for the continuing benefit of the American People.
Last modified: May 04, 2018
All Images Credit to and Courtesy of the U.S. Fish and Wildlife Service Unless Specified Otherwise.
flickr youtube