Office of External Affairs
Mountain-Prairie Region


U.S. Fish and Wildlife Service
Mountain-Prairie Region
134 Union Boulevard
Lakewood, Colorado 80228

April 15, 2010

Beth Dickerson 406-449-5225 ext 220

Diane Katzenberger 303-236-4578


Fish and Wildlife Service to Conduct Status Review of the Northern Rocky Mountain Population of Fisher


A Northern Rocky Mountain distinct population segment of the fisher may warrant federal protection as a threatened or endangered species, the U.S. Fish and Wildlife Service announced today, following an initial review of a petition seeking to protect the fisher under the Endangered Species Act (ESA).  The Northern Rocky Mountain population area includes portions of 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.


Today’s decision, commonly known as a 90-day finding, is based on scientific information about the fisher provided in the petition from Defenders of Wildlife and others requesting the listing of the species under the ESA.  The petition finding does not mean that the Service has decided it is appropriate to give the fisher federal protection under the ESA.  Rather, this finding is the first step in a long process that triggers a more thorough review of all the biological information available.


To ensure this review is comprehensive, the Service is soliciting information from state and federal natural resource agencies and all interested parties regarding the fisher and its habitat. 


The Service is seeking information regarding the fisher’s historical and current status and distribution; its population size and trend; its biology and ecology; its taxonomy and genetics; ongoing conservation measures for the species and its habitat; information on the rangewide status of the fisher to determine if the fisher in the Northern Rocky Mountains constitutes a distinct population segment; and threats to the long-term persistence of the species. 


If listing the fisher in the Northern Rocky Mountains is warranted, the Service intends to propose critical habitat and therefore requests information on what may constitute physical and biological features essential to the conservation of the species; where these features are currently found; whether any of these features may require special management considerations or protection; and whether there are areas outside the geographical area currently occupied by the species that are essential to the conservation of the species.


Scientific information will be accepted until June 15, 2010 and can be submitted electronically via the Federal eRulemaking Portal at:, or can be mailed or hand delivered to Public Comments Processing, Attn: FWS-R6-ES-2010-0017; Division of Policy and Directives Management; U.S. Fish and Wildlife Service, 4401 N. Fairfax Drive, Suite 222; Arlington, VA 22203.


The Service will evaluate all information regarding the status and distribution of the fisher, including the impacts or potential impacts to the species resulting from either human activities or natural causes. 


The Service determined that the Northern Rocky Mountain population of fisher may constitute a distinct population segment because of geographic separateness and possible genetic distinctness from other fisher populations.  The Service also believes this population may be significant because the loss of fisher in the Northern Rocky Mountains may result in a significant gap in the range of the fisher in the United States.


In March 2009, the Defenders of Wildlife, Center for Biological Diversity and others petitioned the Service to list the fisher and designate critical habitat.


The petitioners assert that fisher is threatened by the loss and destruction of habitat from logging and roads, trapping, climate change, disease and predation, and inadequate regulatory mechanisms.


After reviewing the petition, the Service believes that past habitat loss due to logging, fire, and clearing of land for agriculture and settlement together with trapping contributed to the near extermination of fisher populations in the United States.  It is unclear the level to which these activities are a continued threat to the species.  The Service will be investigating these issues in more detail during the status review.


Timber harvest combined with continued commercial forestry and other factors may impact the capacity of the Northern Rocky Mountains to support fisher today.  Fishers rely on large areas of primarily late-successional coniferous forest with fairly dense canopies and large trees, snags, and downed logs for denning and resting. Vegetated understory and large woody debris appear important for fisher prey species.


Fishers have been trapped for commercial purposes since the early 1880s.  Unregulated overtrapping in the past contributed to the reduction in size and extirpation of fisher populations across its range.  Trapping for fisher in Montana is regulated, but because of their low density and low reproductive rate, trapping may adversely affect the fisher.  Trapping for fisher is not legal in Idaho, but incidental capture of fisher occurs in traps set for other legally-harvested species.  There are no verified recent records of fisher in Wyoming.


The petitioners did not present specific information about how global climate change has affected or is likely to affect the fisher in the Northern Rocky Mountains in a way that differs from past climate variability.  Predicting local climate trends and how those trends will affect certain species is uncertain.  Without additional information, the effect of long-term climate change on the fisher is unclear.


The Service found that the other threats cited in the petition were not substantially supported to constitute threats to the species or its habitat.


The fisher (Martes pennanti) is a medium-sized mammal native to North America.  It is light brown to dark blackish-brown, with the face, neck, and shoulders sometimes being slightly gray.  Fishers occur in coniferous and mixed conifer and hardwood forests and avoid areas with little or no cover.  Fishers are opportunistic predators of snowshoe hares, porcupines, squirrels, mice, and birds.  The fisher ranges across the middle of the continent extending from the boreal forests in northern Canada to the northern fringes of the United States. Its original range was much further south but habitat loss and unregulated overtrapping resulted in near extinction in the United States by the early 20th century.  Very little is known of the status of the fisher in the Northern Rocky Mountains but fishers are believed to be distributed in the northwest and west-central Montana and northern and north-central Idaho with rare detection in southwestern Idaho.  Snowtrack surveys reported fisher in Glacier National Park in the 1980s and the Greater Yellowstone area in the late 1990s, but there are no recent verified records of fisher in Wyoming. 


For more information regarding the fisher, please visit our web site at


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