Long-tailed Weasel - Mustela frenata
Largest and most widely distributed of the three Northern American weasels. Distinguished by its long, slender body and long neck. Longest tail of the North American weasels. During summer fur rich brown on the back and sides with yellowish-white under-parts, black tip on tail, and no whitish line down inside of leg. Acquires a white winter coat. Adult males noticeably larger than females. Total length: 11 to 16.5 inches. Weight: three to 12 ounces.
Short-tailed Weasel has white line down inside of leg and is smaller. Least Weasel does not have black tip on tail and is smaller. American Mink is nearly uniform dark brown. Marten is heavier and much larger.
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)
Found in almost all land habitats near water. Has the broadest ecological and geographical range of the North American weasels. Prefers areas with abundant prey. Avoids dense forest, most abundant in late seral ecotones. Primarily nocturnal, but sometimes active during the day. Quite fearless and curious. Mainly terrestrial but can climb and swim well. Nests in old burrows of other animals. Occupies a diverse range of habitats. More prone to open country and forest openings than M. erminea. Common in intermontane valleys and open forests where M. erminea is absent. May occur up to alpine tundra (Hoffmann and Pattie 1968).
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
Human Land Use
Recently Disturbed or Modified
Shrubland, Steppe and Savanna Systems
Sparse and Barren Systems
Wetland and Riparian Systems
- Occasionally Associated with these Ecological Systems
Recently Disturbed or Modified
More of a generalist than the Short-tailed and Least Weasels. Feeds mostly on small mammals up to rabbit-sized, but eats birds and other animals as well. Males: rabbits, tree squirrels, and ground squirrels. FeMales: mice and chipmunks. Dietary componenets overlap. Both sexes will occasionally use birds, herptiles, and insects (Jones et al. 1983).
Weasels will cache prey. This permits food storage without obesity, facilitating ability to pursue prey in narrow burrows. Males about 10 to 15% larger than females (Svendsen 1982).
Mates during summer, 205- to 337-day gestation; delayed implantation; young born during April; litter size four to nine.
- Literature Cited AboveLegend: View Online Publication
- Hoffmann, R.S. and D.L. Pattie. 1968. A guide to Montana mammals: identification, habitat, distribution, and abundance. University of Montana, Missoula. 133 pp.
- Jones, J.K., D.M. Armstrong, R.S. Hoffmann and C. Jones. 1983. Mammals of the northern Great Plains. University of Nebraska Press, Lincoln. 379 pp.
- Svendsen, G. E. 1982. Weasels. Pp. 613-628 in: Hapman, J. A. and G. A. Feldhamer (eds). Wild mammals of North America. John Hopkins Univ. Press, Baltimore. 1147 pp.
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?
- Anaconda Minerals Company, and Camp, Dresser & McKee. 1981. Anaconda Stillwater Project 6-month environmental baseline report. CDM Project No. 3139. Vol. I Appendix. Jan. 15, 1981.
- Andersen, K. W., and J. K. Jones, Jr. 1971. Mammals of northwestern South Dakota. Univ. Kan Mus. Nat. Hist. Pub. 19:361-393.
- Bauer, Delane, 2002, 2002 Four Seasons Wildlife Study. Savage Mine Report, Richland County, Montana.
- Buck, C.L. 1939. Pattern correlation of mammalian teeth as a means of identification. M.Sc. Thesis. Bozeman, Montana: Montana State University. 55 p.
- Chapman, J.A., and G.A. Feldhamer. 1982. Wild mammals of North America: biology, management, and economics. Johns Hopkins University Press, Baltimore, Maryland.
- 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.
- Cross, James, and Richard P. Weckwerth, 1978, Upland Game Bird (and Fur Survey) Inventory. Wildlife Investigations, Region One. W-130-
R-9, Job No. II-1, July 1, 1977 - June 30, 1978.
- Cross, James, and Richard P. Weckwerth, 1980, Upland Game Bird (and Fur Survey) Inventory. Wildlife Investigations, Region One. W-130-
R-11, Job No. II-1, July 1, 1979 - June 30, 1980.
- Cross, James, and Richard P. Weckwerth, 1981, Upland Game Bird (and Fur Survey) Inventory. Wildlife Investigations, Region One. W-130-
R-12, Job No. II-1, July 1, 1980 - June 30, 1981.
- Cross, James, and Richard P. Weckwerth, 1983, Upland Game Bird (and Fur Survey) Inventory. Wildlife Investigations, Region One. W-130-
R-14, Job No. II-1, July 1, 1982 - June 30, 1983.
- ECON, Inc. (Ecological Consulting Service), Helena, MT., 1976, Colstrip 10 x 20 Area wildlife and wildlife habitat annual monitoring report, 1976. Proj. 135-85-A. December 31, 1976.
- Econ, Inc. 1988. Wildlife monitoring report, 1987 field season, Big Sky Mine. March 1988. In Peabody Mining and Reclamation Plan Big Sky Mine Area B. Vol. 8, cont., Tab 10 - Wildlife Resources. Appendix 10-1, 1987 Annual Wildlife Report.
- ECON, Inc., Helena, MT., 1987, Wildlife and habitat characterization, Paupers Dream Mine Project Site, Lewis & Clark and Jefferson Counties, Montana. June 25, 1987. In Pangea Mining Co., Inc., Paupers Dream Project.
- Farmer, Patrick J., and Thomas W. Butts, Western Technology & Eng., Inc., Helena, MT., 1994, McDonald Project Terrestrial Wildlife Study, November 1989 - November 1993. April 1994. In McDonald Gold Project: Wildlife & Fisheries. [#18]. Seven-up Pete Joint Venture, Lincoln, MT. Unpub. No date.
- Farmer, Patrick. J., et al., Western Technology and Eng., Inc., Helena, MT., 1984, Montana Tunnels Project Baseline Terrestrial Wildlife Study. December 14, 1984. In Application for a Hard Rock Operating Permit, Montana Tunnels Project, Jefferson County, Montana. Vol. 3. Environmental Baseline Reports. (Centennial Minerals, Inc., Hydrometrics, 1984?)
- Fitzgerald, B. M. 1977. Weasel predation on a cyclic population of the montane vole (Microtus montanus) in California. J. Anim. Ecol. 46: 367-397.
- Fjell, Alan K., 1986, Peabody Coal Company Big Sky Mine, Rosebud County, MT. Wildlife monitoring report: 1985 field season. March 1986.
- Fjell, Alan K., and Brian R. Mahan, compilers., 1984, Peabody Coal Company Big Sky Mine, Rosebud County, MT. Wildlife monitoring report: 1983 field season. February 1984.
- Fjell, Alan K., and Brian R. Mahan., 1983, Peabody Coal Company Big Sky Mine, Rosebud County, MT. Wildlife monitoring report: 1982 field season. May 1983.
- Fjell, Alan K., and Brian R. Mahan., 1985, Peabody Coal Company Big Sky Mine, Rosebud County, MT. Wildlife monitoring report: 1984 field season. February 1985.
- Fjell, Alan K., and Brian R. Mahan., 1987, Big Sky Mine, Rosebud County, MT. Wildlife monitoring report: 1986 field season. April 1987.
- Foresman, K.R. 2001. The wild mammals of Montana. American Society of Mammalogists, Special Publication Number 12. Lawrence, KS. 278 pp.
- Foresman, K.R. 2012. Mammals of Montana. Second edition. Mountain Press Publishing, Missoula, Montana. 429 pp.
- Graham, Dean, and Craig Swick., 1977, A Field evaluation of the cyclone seeder for reducing Richardson ground squirrel populations causing damage in central Montana . August 1977.
- Haglund, B.M. 1972. Ecological effects of weather modification, Bangtail Ridge, Bridger Range, Montana: relationships of pocket gophers (Thomomys talpoides) to time of snow melt. M.Sc. Thesis. Bozeman, Montana: Montana State University. 26 p.
- Haight, C.P. 1937. Some observations on the predator-prey complex in the Gallatin Valley. M.Sc. Thesis. Bozeman, Montana: Montana State University. 58 p.
- Hanauska-Brown, L., B.A. Maxell, A. Petersen, and S. Story. 2014. Diversity Monitoring in Montana 2008 – 2010 Final Report. Montana Fish, Wildlife & Parks. Helena, MT. 78 pp.
- Hatier, K.G. 1995. Effects of helping behaviors on Coyote packs in Yellowstone National Park, Wyoming. M Sc. Thesis. Bozeman, MT: Montana State University. 78 p.
- Hendricks, P., S. Lenard, D.M. Stagliano, and B.A. Maxell. 2013. Baseline nongame wildlife surveys on the Fort Peck Indian Reservation. Report to the Assiniboine and Sioux Tribes of the Fort Peck Indian Reservation. Montana Natural Heritage Program, Helena, MT. 83 p.
- Hollenbeck, R.R. 1974. Growth rates and movements within a population of Rana pretiosa pretiosa Baird and Girard in south central Montana. Ph.D. Dissertation. Bozeman, Montana: Montana State University. 66 p.
- Johnson, L.J. 1960. Mammal studies on the Lubrecht Forest, Montana: a preliminary report. Proc. Mont. Acad. Sci. 20: 40-47.
- Keith, L. B. and J. R. Cary 1991. Mustelid, squirrel and porcupine population trends during a snowshoe hare cycle. J. Mammal. 72(2):373-378.
- King, C. M. 1989. The natural history of weasels and stoats. Comstock Pub. Assoc. Ithaca, NY. 253 pp.
- Koplin, J.R. 1962. Competition and niche segregation in the genus Microtus. M.S. thesis. Montana State University. 66 pp.
- Lampe, R.P., J.K. Jones Jr., R.S. Hoffmann, and E.C. Birney. 1974. The mammals of Carter County, southeastern Montana. Occa. Pap. Mus. Nat. Hist. Univ. Kan. 25:1-39.
- Matthews, W.L. 1980a. Wibaux-Beach comparison study: Sydney, Glendive and Plevna Study Areas. Bureau of Land Management, Miles City, MT. 50 p.
- Matthews, W.L. 1981. Broadus-Pumpkin Creek baseline inventory - wildlife. Bureau of Land Management, Miles City, MT. 83 p.
- Montana Prairie Dog Working Group. 2002. Conservation plan for black-tailed and white-tailed prairie dogs in Montana. Montana Fish, Wildlife and Parks. Helena MT. 51 pp.
- Morrison-Maierle Env. Corp., Helena, MT., 1993, Biological assessment and wildlife reconnaissance, Holnam Cement Plant, Trident, Montana. In Application to Amend Operating Permit 00004 for Trident Quarries, Three Forks, Montana. Exhibit DD: Wildlife Reconnaisance Study. June 28, 1996.
- Newlon, K.R. 2005. Demography of Lewis's Woodpecker, breeding bird densities, and riparian Aspen integrity in a grazed landscape. M.Sc. Thesis. Bozeman, MT: Montana State University. 101 p.
- 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.
- Pattie, D.L. and N.A. M. Verbeek. 1967. Alpine mammals of the Beartooth Plateau. Northwest Science 41(3): 110-117.
- Reichel, J.D. 1986. Habitat use by alpine mammals in the Pacific Northwest. Arctic and Alpine Research. 18(1): 111-119.
- Reichel, J.D. and S.G. Beckstrom. 1993. Northern bog lemming survey: 1992. Unpublished report. Montana Natural Heritage Program, Helena, MT. 64 pp.
- Reid, F. 2006. Peterson Field Guide to Mammals of North America, 4th Edition. Houghton Mifflin Company: Boston and New York, 608 pp.
- Runge, W. 1993. The long-tailed weasel in Saskatchewan. Saskatchewan Env. and Res. Manage. WL Tech Rep. 93-2. 28 pp.
- Rust, H. J. 1946. Mammals of northern Idaho. J. Mammal. 27(4): 308-327.
- Sheffield, S. R. and H. H. Thomas. 1997. Mustela frenata. American Society of Mammalogists, Lawrence, KS. Mammalian Species No. 570:1-9.
- Simms, D.A. 1979. Studies of an ermine population in southern Ontario. Can. J. Zool. 57:504-520.
- Sullivan, Daniel, and Monty Sullins., 1986, Field evaluation of chlorophacinone treated bait for management of Columbian ground squirrels. Tech. Rep. 86-2. September 1986.
- Thompson, L.S. 1982. Distribution of Montana amphibians, reptiles, and mammals. Bozeman: Montana Audubon Council. 24 pp.
- Thompson, Richard W., Western Resource Dev. Corp., Boulder, CO., 1996, Wildlife baseline report for the Montana [Montanore] Project, Lincoln and Sanders counties, Montana. In Application for a Hard Rock Operating Permit and Proposed Plan of Operation, Montanore Project, Lincoln and Sanders Counties, Montana. Vol. 5. Stroiazzo, John. Noranda Minerals Corp., Libby, MT. Revised September 1996.
- Tschache, O.P. 1970. Effects of ecological changes induced by various sagebrush control techniques on small mammal populations. M.Sc. Thesis. Bozeman, MT: Montana State University. 51 p.
- TVX Mineral Hill Mine, Amerikanuak, Inc., Gardiner, MT., 2002, Yearly summary of wildlife observation reports. 1990-2002 Letter reports.
- Van Horn, R.C. 1993. Ferruginous Hawk and Prairie Falcon reproductive and behavioral responses to human activity near the Kevin Rim, Montana. M.Sc. Thesis. Bozeman, Montana: Montana State University. 86 p.
- Waage, Bruce C., 1996, Western Energy Company Rosebud Mine, Colstrip, Montana: 1995 Annual Wildlife Monitoring Report; December 1, 1994 - November 30, 1995. February 28, 1996.
- Weckwerth, R. P. 1957. The relationship between the marten population and the abundance of small mammals in Glacier National Park. M.S. thesis. University of Montana, Missoula. 76 pp.
- Western Technology and Engineering, Inc. (WESTECH)., 1991, Wildlife Monitoring and Additional Baseline Inventory: Absaloka Mine Area Annual Report, 1991. Montana SMP 85005 R1. OSMP Montana 0007B. Febr. 25, 1991.
- Western Technology and Engineering, Inc., Helena, MT., 1989, Reconnaissance of terrestrial wildlife resources in the Basin Creek Mine Amendment 5 vicinity, 1988-1989. November 1989. In Basin Creek Mine Permit Amendment No. 5 - Paupers Pit Southwest, Block B and leach Pad No. 3. Basin Creek Mining, Inc. (Pegasus Gold Corp.). For Montana Dept. of State Lands and USFS Deer Lodge NF.
- Zackheim, K. 1973. Exhibit H: Wildlife Study. In Ash Grove Cement Co. files.
- Additional Sources of Information Related to "Mammals"