Mustela frenata


Taxonomy [top]

Kingdom Phylum Class Order Family

Scientific Name: Mustela frenata
Species Authority: Lichtenstein, 1831
Common Name(s):
English Long-tailed Weasel
Spanish Comedreja Andina

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2008
Date Assessed: 2008-06-30
Assessor(s): Reid, F. & Helgen, K.
Reviewer(s): Duckworth, J.W. (Small Carnivore Red List Authority) & Schipper, J. (Global Mammal Assessment Team)
This species is listed as Least Concern as the species has a wide distribution range and is relatively common across its range. This species is tolerant to a moderate amount of land-use change and can often benefit from human presence. However, M. frenata populations generally fluctuate, and they frequently become locally extinct in response to changes in prey numbers (King 1989).

Geographic Range [top]

Range Description: Long-tailed weasels have the largest distribution of any mustelid in the Western Hemisphere. The range of the long-tail weasel includes most of North America, extending from just north of the United States-Canadian border and south to Central America to northern South America (Sheffield and Thomas, 1997). In South America it is known from Columbia, Venezuela, Ecuador, Peru, and Bolivia (Eisenberg, 1989; Emmons and Feer, 1990; King, 1989).
Belize; Bolivia, Plurinational States of; Brazil; Canada; Colombia; Costa Rica; Ecuador; El Salvador; Guatemala; Honduras; Mexico; Nicaragua; Panama; Peru; United States; Venezuela, Bolivarian Republic of
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Long-tailed weasels are widespread and fairly common throughout their range (Wilson and Ruff, 1999). M. frenata is difficult to census. Estimates of densities vary widely by habitat and prey availability (King, 1989). Population density was found to vary from about 1/2.6 ha to 1/260 ha (Nowak, 2005). Jackson (1961) found population density averages 1 per 7-40 acres, depending upon habitat and environmental conditions (Baker 1983). M. frenata populations are more stable than those of M. erminea or M. nivalis. However, M. frenata populations generally fluctuate, and they frequently become locally extinct in response to changes in prey numbers (King, 1989).
Population Trend: Stable

Habitat and Ecology [top]

Habitat and Ecology: Found in a wide variety of habitats, usually near water. Favored habitats include brushland and open woodlands, field edges, riparian grasslands, swamps, and marshes (Sheffield, in Wilson and Ruff 1999). Dens are in abandoned burrow made by other mammal, rock crevice, brushpile, stump hollow, or space among tree roots; one individual may use multiple dens. Tolerant of close proximity to humans.

M. frenata is usually most abundant in late seral stages or ecotones where prey diversity is greatest (Wilson and Ruff, 1999). Its diet consists mainly of rodents and other small mammals. It is primarily nocturnal but is frequently active by day. It can climb and swim, but apparently not as well as M. erminea. Waterways provide access to suitable habitat and are a natural avenue far dispersal, particularly in areas that otherwise are unsuitable (Fagerstone, 1987). Home ranges vary from 4 to 120 ha and may overlap. Basically solitary, though more social where prey is abundant and habitat optimal.
Systems: Terrestrial

Threats [top]

Major Threat(s): Movements of radio-tagged weasels in Indiana were consistent with the notion that long-tailed weasels may be sensitive to agriculturally induced fragmentation of habitat and the importance of maintaining landscape connectivity for species conservation (Gehring and Swihart, 2004). Additional threats include monoculture and drainage of wetlands. Perhaps affected directly and indirectly by pesticide use (effects on reproduction, habitat, and/or food supply).

Conservation Actions [top]

Conservation Actions: The species occurs in many protected areas across its range.

Bibliography [top]

Baker, R. H. 1983. Michigan mammals. Michigan State University Press.

Eisenberg, J.F. 1989. Mammals of the Neotropics. The Northern Neotropics. The University of Chicago Press, Chicago, USA and London, UK.

Emmons, L.H. and Feer, F. 1990. Neotropical Rainforest Mammals: A Field Guide. University of Chicago Press, Chicago, USA and London, UK.

Fagerstone, K. A. 1987. Black-footed ferret, long-tailed weasel, short-tailed weasel, and least weasel. In: M. Novak, J. A. Baker, M. E. Obbard and B. Malloch (eds), Wild furbearer management and consewation in North America, pp. 548-573. Ontario Ministry of Natural Resources and the Ontario Trappers Association, Ontario, Canada, Toronto, Ontario, Canada.

Gamble, R. L. 1981. Distribution in Manitoba of Mustela frenata longicauda Bonaparte, the long-tailed weasel, and the interrelation of distribution and habitat selection in Manitoba, Saskatchewan, and Alberta. Canadian Journal of Zoology 59: 1036-1039.

Gehring, T. M. and Swihart, R. K. 2003. Body size, niche breadth, and ecologically scaled responses to habitat fragmentation: mammalian predators in an agricultural landscape. Biological Conservation 109: 283-295.

Gehring, T. M. and Swihart, R. K. 2004. Home range and movements of long-tailed weasels in a landscape fragmented by agriculture. Journal of Mammalogy 85: 79-86.

King, C. M. 1989. The natural history of weasels and stoats. Christopher Helm Publishers, London, UK.

Nowak, R. M. 2005. Walker’s Carnivores of the world. Johns Hopkins University Press, Baltimore, USA and London, UK.

Sheffield, S. R. and Thomas, H. H. 1997. Mustela frenata. Mammalian Species 570: 1-9.

Wilson, D. E. and Ruff, S. 1999. The Smithsonian Book of North American Mammals. Smithsonian Institution Press, Washington, DC, USA.

Citation: Reid, F. & Helgen, K. 2008. Mustela frenata. The IUCN Red List of Threatened Species. Version 2015.2. <>. Downloaded on 01 July 2015.
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