View in other NatureServe Network Field Guides
Fisher - Pekania pennanti
The Fisher is a medium-sized mammal with a long, low stocky body. The tail is relatively long and heavily furred. They have a pronounced muzzle and large rounded ears. In winter, Fishers are dark brown to black with light colored hairs around the face and shoulders (Powell 1993). The undersides are uniformly brown, however, individually unique patterns of white or cream can occur on the chest, underarms or genital region (Powell 1993). The summer pelage is more variable and lighter in color. Molt occurs once per year in late summer and early autumn (Powell 1993). The feet are large and have 5 retractable, but not sheathed, claws (Powell 1993). Fishers are highly sexually dimorphic with males averaging nearly twice the size of females. Male fishers generally weigh between 3.5 and 5.5 kilograms with females weighing between 2.0 and 2.5 kilograms (Powell 1993).
Fishers are not easily confused with other mustelids in Montana. They are much larger than the American Mink and are much darker than the slightly smaller Marten. Fisher are smaller than Wolverine and have a longer tail and a lower, longer appearance overall.
Western Hemisphere Range
Observations in Montana Natural Heritage Program Database
Number of Observations:
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
(Observations spanning multiple months or years are excluded from time charts)
Fishers are non-migratory, but may make extensive movements up to a maximum of 40 kilometers in 3 days (Hash and Hornocker 1979).
Although they are primarily terrestrial, Fishers are well adapted for climbing. When inactive, they occupy dens in tree hollows, under logs, or in ground or rocky crevices, or they rest in branches of conifers (in the warmer months). Fishers occur primarily in dense coniferous or mixed forests, including early successional forests with dense overhead cover (Thomas 1993). They commonly use hardwood stands in summer but prefer coniferous or mixed forests in winter and avoid open areas. Optimal conditions for Fishers are forest tracts of 245 acres or more, interconnected with other large areas of suitable habitat. A dense understory of young conifers, shrubs, and herbaceous cover is important in summer.
Forest structure, which affects prey abundance and vulnerability and provides denning and resting sites for Fishers, is probably more important than tree species composition (Buskirk and Powell 1994). Forest structure can be characterized by a diversity of tree shapes and sizes, understory vegetation, snags and fallen limbs and trees, and tree limbs close to the ground (Buskirk and Powell 1994).
Young are born in a den in a tree hollow (usually), or under a log or in a rocky crevice. Large snags (greater than 20 inches diameter at breast height) are important as maternal den sites (Thomas 1993).
Ecological Systems Associated with this Species
- Details on Creation and Suggested Uses and Limitations
How Associations Were Made
We associated the use and habitat quality (common or occasional) of each of the 82 ecological systems mapped in Montana for
vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
- Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2012, Adams 2003, and Werner et al. 2004);
- Evaluating structural characteristics and distribution of each ecological system relative to the species' range and habitat requirements;
- Examining the observation records for each species in the state-wide point observation database associated with each ecological system;
- Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of "observations versus availability of habitat".
Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.
In general, species were listed as associated with an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.
However, species were not listed as associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if
point observations were associated with that system.
Common versus occasional association with an ecological system was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species as represented in scientific literature.
The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignment of common versus occasional association.
If you have any questions or comments on species associations with ecological systems, please contact the Montana Natural Heritage Program's Senior Zoologist.
Suggested Uses and Limitations
Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.
These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: mtnhp.org/requests
) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.
Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.
Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.
Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).
Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species' known geographic range.
- Adams, R.A. 2003. Bats of the Rocky Mountain West; natural history, ecology, and conservation. Boulder, CO: University Press of Colorado. 289 p.
- Dobkin, D. S. 1992. Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34. Missoula, MT.
- Foresman, K.R. 2012. Mammals of Montana. Second edition. Mountain Press Publishing, Missoula, Montana. 429 pp.
- Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998. Montana atlas of terrestrial vertebrates. Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT. 1302 p.
- Hutto, R.L. and J.S. Young. 1999. Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32. 72 p.
- Maxell, B.A. 2000. Management of Montana's amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species. Report to U.S. Forest Service Region 1. Missoula, MT: Wildlife Biology Program, University of Montana. 161 p.
- Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath. 2004. Amphibians and reptiles of Montana. Missoula, MT: Mountain Press Publishing Company. 262 p.
- Commonly Associated with these Ecological Systems
Forest and Woodland Systems
Recently Disturbed or Modified
Wetland and Riparian Systems
- Occasionally Associated with these Ecological Systems
Forest and Woodland Systems
Shrubland, Steppe and Savanna Systems
Wetland and Riparian Systems
Diet consists primarily of mammals (small rodents, shrews, squirrels, hares, Muskrat, Beaver, Porcupine, Raccoon, deer carrion); also birds and fruit. Snowshoe Hares are an important dietary item for Fishers in Montana, as is deer carrion (Foresman 2012). Fishers are also well known for their skill at killing Porcupines and have been implicated as the only predator capable of regulating Porcupine populations (Powell 1993).
Fishers are generally solitary except during the breeding season. Home ranges have been estimated at 10 to 800 square kilometers by snow tracking, and 7 to 78 square kilometers by telemetry using a minimum convex polygon model. Generally, the ranges of adults of the same sex do not overlap. In Maine, home ranges of females were stable between seasons and years, but males moved extensively in late winter and early spring and their ranges shifted between years. In New Hampshire, mean annual home range was about 15 to 25 square kilometers, with daily movements of 1.5 to 3.0 kilometers. In southern Quebec, mean home range size was 5.4 square kilometers for females and 9.2 square kilometers for males (Garant and Crete 1997). Fishers have been recorded moving 90 kilometers in 3 days (Nowak 1991).
Population density in favorable habitat has been estimated at up to about 1 per 3 to 11 square kilometers in summer, and 1 per 8 to 20 square kilometers in winter (Arthur et al. 1989). In southern Quebec, density was estimated at about 3 individuals per 10 square kilometers; the high density was attributed to the absence of trapping (Garant and Crete 1997).
No specific information on Fisher reproductive biology is available for Montana. Information gathered in other portions of the range suggests that Fishers breed in late February to April or March to May. Females probably mate within days of giving birth. The implantation of the embryo is delayed for 11 months after mating. Parturition occurs approximately one month after implantation and renewed development of the embryo (Foresman 2012). Litter sizes average about three throughout the range. Births occur primarily from March to mid-April (sometimes in February or May in some areas). Young are mobile by 8 weeks and are weaned in 2.5 to 4 months. Separation from the mother occurs in the fifth month, in late summer or early fall. In Maine, young are weaned from mid-May to early June and are independent probably in late August or early September (Arthur and Krohn 1991). Fishers are sexually mature in 1 to 2 years but not all adult females will breed in a given year.
Fishers were extinct in Montana by the 1930's (Foresman 2012). Reintroduction efforts in 1959 and 1960 in Lincoln, Granite and Missoula counties resulted in the establishment of populations in those counties. More recent reintroductions were made in the Cabinet Mountains between 1988 and 1991 (Foresman 2012). The species is currently managed as a furbearer with a limited harvest of 7 animals. Consult Montana Fish, Wildlife and Parks for current trapping regulations. Additional information concerning Fisher management can be found in Ruggiero et al. (1994).
On October 5, 2017, the U.S. Fish and Wildlife Service determined that Fisher in the Northern Rocky Mountains of western Montana, central and northern Idaho, and possibly northeastern Washington does not warrant listing under the Endangered Species Act at this time (USFWS 2017). Additional information on the species' management can be found on the U.S. Fish and Wildlife Service's Species Account
- Literature Cited AboveLegend: View Online Publication
- Arthur, S. M., W. B. Krohn, and J. R. Gilbert. 1989. Home range characteristics of adult fishers. Journal of Wildlife Management 53(3):674-679.
- Arthur, S.M. and W.B. Krohn. 1991. Activity patterns, movements, and reproductive ecology of fishers in southcentral Maine. Journal of Mammology 72:379-385.
- Buskirk, S.W. and R.A. Powell. 1994. Habitat ecology of fishers and American martens. pp. 283-296. In: Buskirk, S. W., A.S. Harestad, and M.G. Raphael (eds). Martens, sables and fishers: biology and conservation. Cornell University Press, Ithica, New York.
- Foresman, K.R. 2012. Mammals of Montana. Second edition. Mountain Press Publishing, Missoula, Montana. 429 pp.
- Garant, Y. and M. Crete. 1997. Fisher, Martes pennanti, home range characteristics in a high density untrapped population in southern Quebec. Canadian Field-Naturalist 111:359-364.
- Hash, H. S. and M. G. Hornocker. 1979. Range and habitat of male fishers in northwest Montana. Idaho Cooperative Wildlife Research Unit. University of Idaho, Moscow. 10 pp.
- Nowak, R.M. 1991. Walker's mammals of the world. Fifth edition. Volumes I and II. Johns Hopkins University Press, Baltimore. 1629 pp.
- Powell, R.A. 1993. The fisher: life history, ecology, and behavior. University of Minnesota Press, Minneapolis. 237 pp.
- Ruggiero, L.F., K.B. Aubry, S.W. Buskirk, L.J. Lyon, and W.J. Zielinski. 1994. The scientific basis for conserving forest carnivores: American marten, fisher, lynx, and wolverine in the western United States. Fort Collins, CO: General Technical Report RM-254. U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 184 p.
- Thomas, J.W. 1993. Viability assessments and management considerations for species associated with late-successional and old-growth forests of the Pacific Northwest. USDA, National Forest System, Forest Service Research, Portland, OR.
- U.S. Fish and Wildlife Service. 2017. Endangered and threatened wildlife and plants; 12-month findings on petitions to list 25 species as Endangered or Threatened Species. Federal Register 82(192):46618-46645.
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?
- Allen, A. W. 1983. Habitat suitability index models: fisher. U.S. Fish and Wildl. Serv. FWS/OBS-82/10.45. 19 pp.
- Allen, A.W. 1987. The relationship between habitat and furbearers. Pages 164-179 in M. Novak, J.A. Baker, M.E. Obbard, and B. Malloch, eds. Wild Furbearer Management and Conservation in North America. Ontario Trappers Assn. and Ontario Ministry Nat. Res., Toronto, Ontario.
- Alt, Kurt, 1984, II Game Bird and Fur (Small Game) Survey and Inventory. Statewide Wildlife Survey and Inventory. Region Two Survey and Inventory. W-130-R-15, Job No. 2, July 1, 1983 - June 30, 1984.
- Alt, Kurt, John E. Firebaugh, Lyn S. Nielsen, and Robert Henderson, 1985, II Game Bird and Fur (Small Game) Survey and Inventory. Statewide Wildlife Survey and Inventory. Region Two Survey and Inventory. W-130-R-16, Job No. 2, July 1, 1984 - June 30, 1985.
- Alt, Kurt, John E. Firebaugh, Lyn S. Nielsen, and Robert Henderson, 1987, II Game Bird and Fur (Small Game) Survey and Inventory. Statewide Wildlife Survey and Inventory. Region Two Survey and Inventory. W-130-R-18, Job No. 2, July 1, 1986 - June 30, 1987.
- Alt, Kurt., John E. Firebaugh, Lyn S. Nielsen, and Robert Henderson, 1986, Statewide Wildlife Survey and Inventory. II Game Bird and Fur (Small Game) Survey and Inventory. Region Two Survey and Inventory. W-130-R-17, Job No. 2, July 1, 1985 - June 30, 1986.
- Arthur, S. M. 1989. Habitat use and diet of fishers. J. Wildl. Manage. 53(3):680-688.
- Aubry, K.B. and D. B. Houston. 1992. Distribution and status of the fisher (Martes pennanti) in Washington. Northwest Nat. 73:69-79.
- Banci, V. 1994. Wolverine. Pp. 99-127. IN: Ruggiero, L. F., K. B. Aubry, S. W. Buskirk, L. J. Lyon, amd W. J. Zielinski (eds.), The scientific basis for conserving forest carnivores, American marten, fisher, lynx, and wolverine in the western United States. U.S.D.A, Forest Serv. Rocky Mountain Forest and Range Exper. Stat. Gen. Tech. Report RM-254. 184 pp.
- Berg, W. E. 1982. Reintroduction of fisher, pine marten, and river otter. Pages 159-173 in G. C. Sanderson, editor. Midwest furbearer management. Proc. Symp. 43rd Midwest Fishand Widlife Conference, Wichita, Kansas.
- Brown, L.N. 1965. A fisher, Martes pennanti, in Sheridan County, Wyoming. Southwestern Naturalist 10(2):143.
- Buskirk, S. W. 1992. Conserving circumboreal forests for martens and fishers. Cons. Biol. 6:318-320.
- Clark, T.W., H.A. Harvey, R.D. Dorn, D.L. Genter, and C. Groves (eds). 1989. Rare, sensitive, and threatened species of the greater Yellowstone ecosystem. Northern Rockies Conservation Cooperative, Montana Natural Heritage Program, The Nature Conservancy, and Mountain West Environmental Services. 153 p.
- Cross, James, and Richard P. Weckwerth, 1972, Upland Game Bird (Fur Survey Inventory). Wildlife Investigations, Region One. W-130-R-3, Job No. II-1, July 1, 1971 - June 30, 1972.
- Cross, James, and Richard P. Weckwerth, 1974, Upland Game Bird (and Fur Survey) Inventory. Wildlife Investigations, Region One. W-130-R-5, Job No. II-1, July 1, 1973 - June 30, 1974.
- Cross, James, and Richard P. Weckwerth, 1976, Upland Game Bird (and Fur Survey) Inventory. Wildlife Investigations, Region One. W-130-R-7, Job No. II-1, July 1, 1975 - June 30, 1976.
- Cross, James, and Richard P. Weckwerth, 1977, Upland Game Bird (and Fur Survey) Inventory. Wildlife Investigations, Region One. W-130-R-8, Job No. II-1, July 1, 1976 - June 30, 1977.
- Deems, E.F., Jr. and D. Pursley (eds). 1978. North American furbearers: their management, research and harvest status in 1976. Int. Assoc. Fish and Wildlife Agencies and University of Maryland. 171 p.
- Fikkan, P., J. Fikkan, J. Collier, and R. Kresek. 1973. Some observations of a Fisher at close range. The Murrelet 54(2):22
- Firebaugh, John E., 1980, II Game Bird and Fur (Small Game) Survey and Inventory. Statewide Wildlife Survey and Inventory. Region Two Survey and Inventory. W-130-R-11, Job No. 2, July 1, 1979 - June 30, 1980.
- Flathead National Forest. U.S. Forest Service., 1993, Wildlife landscape evaluation, Swan Valley. Draft Report.
- Foresman, K.R. 2001. The wild mammals of Montana. American Society of Mammalogists, Special Publication Number 12. Lawrence, KS. 278 pp.
- Hagmeier, E. M. 1956. Distribution of marten and fisher in North America. Can. Field-Nat. 70:149-168.
- Handley, C. O., Jr. 1991. Mammals. Pages 539-616 in K. Terwilliger, coordinator. Virginia's endangered species: proceedings of a symposium. McDonald and Woodward Publishing Company, Blacksburg, Virginia.
- Hawley, V. D. 1960. Fisher are returned to Montana forests. Montana Wildlife. July.
- Heinemeyer, K. S. and J. L. Jones 1994. Fisher biology and management: a literature review and adaptive management strategy. USDA For. Serv. Northern Region, Missoula, MT. 108 pp.
- Hoffmann, R.S. and D.L. Pattie. 1968. A guide to Montana mammals: identification, habitat, distribution, and abundance. Missoula, MT: University of Montana. 133 p.
- Hoffmann, R.S., P.L. Wright, and F.E. Newby. 1969. The distribution of some mammals in Montana. I. Mammals other than bats. Journal of Mammalogy 50(3): 579-604.
- Holbrook, J.D., J.R. Squires, L.E. Olson, N.J. DeCesare, and R.L. Lawrence. 2017. Understanding and predicting habitat for wildlife conservation: the case of Canada Lynx at the range periphery. Ecosphere 8(9):e01939.
- Janson, Reuel G., 1977, II Game Bird and Fur (Small Game) Survey and Inventory. Statewide Wildlife Survey and Inventory. Region Two Survey and Inventory. W-130-R-8, Job No. 2, July 1, 1976 - June 30, 1977.
- Janson, Reuel G., 1978, II Game Bird and Fur (Small Game) Survey and Inventory. Statewide Wildlife Survey and Inventory. Region Two Survey and Inventory. W-130-R-9, Job No. 2, July 1, 1977 - June 30, 1978.
- Janson, Reul G., 1976, II Game Bird and Fur (Small Game) Survey and Inventory. Statewide Wildlife Survey and Inventory. Region Two Survey and Inventory. W-130-R-7, Job No. 2, July 1, 1975 - June 30, 1976.
- Joslin, Gayle, and Heidi B. Youmans. 1999. Effects of recreation on Rocky Mountain wildlife: a review for Montana. [Montana]: Montana Chapter of the Wildlife Society.
- Kilpatrick, H.J., and P.W. Rego. 1994. Influence of season, sex, and site availability on fisher (Martes pennanti) rest-site selection in the central hardwood forest. Canadian Journal of Zoology 72:1416-1419.
- Maj, M., and E. O. Garten. 1994. Fisher, lynx, wolverine: Summary of distribution information. Pp. 169-175. IN: Ruggiero, L. F., K. B. Aubry, S. W. Buskirk, L. J. Lyon, amd W. J. Zielinski (eds.), The scientific basis for conserving forest carnivores, American marten, fisher, lynx, and wolverine in the western United States. U.S.D.A, Forest Serv. Rocky Mountain Forest and Range Exper. Stat. Gen. Tech. Report RM-254. 184 pp.
- Nielsen, Lyn S., 1983, II Game Bird and Fur (Small Game) Survey and Inventory. Statewide Wildlife Survey and Inventory. Region Two Survey and Inventory. W-130-R-14, Job No. 2, July 1, 1982 - June 30, 1983.
- Oechsli, L.M. 2000. Ex-urban development in the Rocky Mountain West: consequences for native vegetation, wildlife diversity, and land-use planning in Big Sky, Montana. M.Sc. Thesis. Montana State University, Bozeman. 73 p.
- Powell, R. A. 1981. Martes pennanti. American Society of Mammalogists, Lawrence, KS. Mammalian Species No. 156:1-6.
- Powell, R. A. 1994. Fisher. Pages 38-66 in Ruggerio et al. editors. The Scientific Basis for Conservation of Forest Carnivores: American Marten, Fisher, Lynx, and Wolverine in the Western United States. USDA Forest Service General Technical Report RM-254. Fort Collins, Colorado.
- Powell, R.A. 1982. The fisher: life history, ecology, and behavior. Univ. Minnesota Press. xvi + 217 pp.
- Raine, R.M. 1983. Winter habitat use and responses to snow cover of fisher (Martes pennanti) and marten (Martes americana) in southeastern Manitoba. Can. J. Zool. 61:25-34.
- Raine, R.M. 1987. Winter food habits and foraging behavior of fishers (Martes pennanti) and martens (Martes americana) in southeastern Manitoba. Can. J. Zool. 65: 745-747.
- Reid, F. 2006. Peterson Field Guide to Mammals of North America, 4th Edition. Houghton Mifflin Company: Boston and New York, 608 pp.
- Roy, K. D. 1991. Ecology of reintroduced fishers in the Cabinet Mountains of northwest Montana. M.S. thesis. University of Montana, Missoula. 94 pp.
- Rust, H. J. 1946. Mammals of northern Idaho. J. Mammal. 27(4): 308-327.
- Sato, J.J., M. Wolsan, F.J. Prevosti, G. D'Elia, C. Begg, K. Begg, T. Hosoda, K.L. Campbell, H. Suzuki. 2012. Evolutionary and biogeographic history of weasel-like carnivorans (Musteloida). Molecular Phylogenics and Evolution 63:745-757.
- Thomasma, L. E., T. D. Drummer, and R. O. Peterson. 1991. Testing the habitat suitability index model for the fisher. Wildl. Soc. Bull. 19:291-297.
- Thompson, L.S. 1982. Distribution of Montana amphibians, reptiles, and mammals. Bozeman: Montana Audubon Council. 24 pp.
- Tweten, R.G. 1984. Baseline survey of furbearing mammals within the South Fork drainage Sun River, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 63 p.
- Vinkey, R.S. 2003. An evaluation of fisher (Martes pennanti) introductions in Montana. M.S. Thesis. University of Montana. Missoula, MT. 97 pp.
- Waller, John. 2018. Status of Fishers in Glacier National Park, Montana. Northwestern Naturalist. 99(1):1-8.
- Weckwerth, R. P. and P. L. Wright. 1968. Results of transplanting fishers in Montana. J. Wildl. Manag. 32(4):977-981.
- Zielinski, W.J. and T.E. Kucera. 1995. American marten, fisher, lynx, and wolverine: survey methods for their detection. Berkeley, CA: USDA Forest Service Pacific SW Research Station, Gen. Tech. Rep. PSW-GTR-157. 163 p.
- Web Search Engines for Articles on "Fisher"
- Additional Sources of Information Related to "Mammals"