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Montana Animal Field Guide

Montana Field Guides

Short-tailed Weasel - Mustela erminea

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Global Rank: G5
State Rank: S5

Agency Status
USFWS:
USFS:
BLM:
FWP Conservation Tier: 3


 

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General Description
Of the three North American weasels (Genus Mustela), the Short-tailed Weasel is intermediate in size. Males are distinctly larger than females of the same age. During summer the fur is dark brown with white (not buff) under-parts, white feet, and white along the inside of the hind legs. The tip of the tail is black. Molts to entirely white during winter, except for the black on the tip of the tail. Total length: seven to 13 inches. Weight: one to six ounces.

Diagnostic Characteristics
Long-tailed Weasel is larger and tail its is longer. Least Weasel is smaller, has a short tail, and lacks a black tip on the tail. American Mink are larger with a uniform color.

General Distribution
Montana Range



Western Hemisphere Range

 


Summary of Observations Submitted for Montana
Number of Observations: 123

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density

Recency

 

(Records associated with a range of dates are excluded from time charts)



Migration
Non-migratory.

Habitat
Inhabits brushy or wooded areas, usually not far from water. Tends to avoid dense forests. Prefers areas with high densities of small mammals. Most abundant in ecotones. Mostly nocturnal but will hunt during the day. Active throughout the year. Dens in ground burrows, under stumps, rock piles, or old buildings. In Montana, apparently prone to montane forest associations. Elsewhere occupies a diverse range of habitats. Nests in hollow trees, rock piles or burrows.

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 (high, medium, or low) of each of the 82 ecological systems mapped in Montana for vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
    1. 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 2001, Adams 2003, and Werner et al. 2004);
    2. Evaluating structural characteristics and distribution of each ecological system relative to the species’ range and habitat requirements;
    3. Examining the observation records for each species in the state-wide point database associated with each ecological system;
    4. 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 associated as using 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 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.  High, medium, and low habitat quality was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species in the 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 assignments of habitat quality.  If you have any questions or comments on species associations with ecological systems, please contact Bryce Maxell at bmaxell@mt.gov or (406) 444-3655.

    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: http://mtnhp.org/requests/default.asp) 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.

    Literature Cited
    • 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.  2001.  The wild mammals of Montana.  Special Publication No. 12.  Lawrence, KS: The American Society of Mammalogists.  278 p.
    • 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.

Food Habits
Short-tailed Weasels prey on a variety of small mammals and birds, they specialize in hunting voles. Mostly small warm-blooded vertebrates, primarily cricetidae. Hunts under snow in winter. Females generally eat smaller prey. May use invertebrates. Short-tailed Weasels will kill larger prey such rabbits.

Ecology
As in many mustelids, two degrees sexual dimorphism is pronounced. Males 30% larger than females. Local distribution and densities probably tied to prey availability. Well adapted to snowy environments.

Reproductive Characteristics
Breeds during summer (June to July); 8.5- to 10-month gestation; delayed implantation; young born April or May; one litter per year of four to 13 young. Induced ovulation. 8.5 to 9 months delay of implantation. Females first breed at 2.5 months. Males at 14 months.

References
  • Additional ReferencesLegend:   View WorldCat Record   View Online Publication
    Do you know of a citation we're missing?
    • Butts, Thomas W., Western Technology and Eng., Helena, MT., 1993, Continental Lime Indian Creek Mine, Townsend, MT. 1993 Life of Mine Wildlife Reconnaissance. June 1993. In Life-of-Mine Amendment. Continental Lime, Inc., Indian Creek Mine & Plant. Vol. 2. October 13, 1992.
    • Chapman, J. A., and G. A. Feldhamer, editors. 1982. Wild mammals of North America: biology, management, and economics. Johns Hopkins University Press, Baltimore, Maryland.
    • Fitzgerald, B. M. 1977. Weasel predation on a cyclic population of the montane vole (Microtus montanus) in California. J. Anim. Ecol. 46: 367-397.
    • Foresman, K. R. 2001. The wild mammals of Montana. American Society of Mammologists, Special Publication Number 12. Lawrence, KS. 278 p.
    • Geppert, T. J. 1984. Small mammals of the Shield Trap, East Pryor Mountain, Montana. M.S. thesis. University of Iowa, Iowa City. 45 pp.
    • Hoffmann, R. S. and D. L. Pattie. 1968. A guide to Montana mammals: identification, habitat, distribution, and abundance. University of Montana, Missoula. 133 p.
    • http://mdt.mt.gov/research/docs/research_proj/animal_use/animal.pdf
    • 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. 1983. MUSTELA ERMINEA. Mamm. Species No. 195. 8 pp.
    • King, C. M. 1989. The natural history of weasels and stoats. Comstock Pub. Assoc. Ithaca, NY. 253 pp.
    • Pattie, D. L. and N. A. M. Verbeek. 1967. Alpine mammals of the Beartooth Plateau. Northwest Science 41(3): 110-117.
    • Quick, H.F. 1951. Notes on the ecology of weasels in Gunnison County, Colorado. J. Mammal. 32: 281-290.
    • Reid, F. 2006. Peterson Field Guide to Mammals of North America, 4th Edition. Houghton Mifflin Company: Boston and New York, 608 pp.
    • Rust, H. J. 1946. Mammals of northern Idaho. J. Mammal. 27(4): 308-327.
    • Simms, D.A. 1979. Studies of an ermine population in southern Ontario. Can. J. Zool. 57:504-520.
    • Stearns-Roger Inc., 1975, Environmental baseline information of the Mount Vernon Region, Montana. January 31, 1975.
    • 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.
    • Western Technology and Engineering, Inc. (WESTECH)., 1997, Wildlife Monitoring Absaloka Mine Area Annual Report, 1996. Montana SMP 85005. OSMP Montana 0007D. Mar. 1997.
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Citation for data on this website:
Short-tailed Weasel — Mustela erminea.  Montana Field Guide.  Montana Natural Heritage Program and Montana Fish, Wildlife and Parks.  Retrieved on July 31, 2014, from http://FieldGuide.mt.gov/detail_AMAJF02010.aspx
 
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