Weasel

The Weasel is a small, long-bodied, carnivorous MAMMAL of the family Mustelidae. Three occur in Canada: the short-tailed weasel, ermine or stoat (Mustela erminea); long-tailed and least weasels (M. frenata, M. nivalis, respectively). The least weasel is the smallest species in the order CARNIVORA. Genus Mustela also includes MINK, black-footed FERRET and the introduced European ferret.

Description
Weasels have dark brown upper bodies and tails and creamy white to orangish underparts. They assume a white winter coat in northern regions. In the FUR INDUSTRY no distinction is made among the coats of the 3 species; all are marketed as ermine. The weasel's head is bluntly pointed; its ears, small and rounded. The long, slender body has a thick neck and short feet.

Distribution and Habitat
Weasels occur throughout mainland Canada from interior BC to northern Ontario and Québec. They prefer coniferous FOREST or TUNDRA but also inhabit marshes, meadows and broken woodlands. Long-tailed weasels, the largest species, occur from South America to about 49° North latitude and are found in southern British Columbia, the PRAIRIES, Ontario, Québec and New Brunswick. They prefer mixed hardwood forest but also inhabit other forests or open country, always near water.

The short-tailed weasel, widespread in the northern hemisphere, occurs throughout Canada in habitats including tundra, BOREAL FOREST, meadows and riverbanks. Least weasels are also widespread in Canada. They are as small as the mice on which they prey. All species take small mammals and INSECTS; long-tailed and short-tailed weasels also take young RABBITS and larger rodents.

Reproduction and Development
Long-tailed weasels breed in July to August; 4-9 young are born 205-237 days later. Delayed implantation of the embryo accounts for the long gestation. Short-tailed weasels mate in March; gestation lasts about 30 days; the single litter averages 6 young.

Least weasels breed throughout the year, with a 35-day gestation period. They bear 2-3 litters annually, each of 3-6 young (range 1-9). Adulthood is reached at 120 days for females and 250 days for males.

In all species males, may assist females in hunting food for young.

Relationship with Humans
As efficient killers of MICE, weasels are useful to farmers, except when they take poultry.

Other Members of the Weasel Family
Other members of the weasel family, Mustelidae, represented in Canada include the BADGER, FISHER, MARTEN and WOLVERINE, the largest mustelid. There are 3 that spend some or most of their time in water: MINK and OTTER in freshwater and the marine SEA OTTER.

Author C.S. CHURCHER

Links to Other Sites
Natural History Notebooks
View illustrated descriptions of a huge variety of Canadian animal species, prehistoric creatures, and endangered/extinct animals. A Canadian Museum of Nature website.

Canadian Biodiversity Website
A great information source for all budding biologists. Learn about biodiversity theory, natural history, and conservation issues. From McGill’s Redpath Museum.