Family: Mustelidae, Weasels view all from this family
Description A tiny weasel. Brown above, white below. Tail very short, brown. Feet white. All white in winter in North. L 6 3/4-8 1/8" (172-206 mm); T 7/8-1 1/4" (24-38 mm); HF 3/4-7/8" (19-23 mm); Wt 1 1/4-1 3/4 oz (37-50 g).
Similar Species Short-tailed Weasel and Long-tailed Weasel both are larger and have much longer, black-tipped tails. Black-footed Ferret is yellowish brown, with dark or black mask around eyes.
Breeding Mates year-round. Ovulation is induced by copulation; no delayed implantation. Gestation 34-37 days. Up to 3 litters per year of 1-6 young, usually born in spring and late summer, often in abandoned burrow of another animal. Young weigh less than 1/16 oz (1.4 g) at birth; they are weaned at 6-7 weeks.
Habitat Grassy and brushy fields, marsh areas; also deep forests of high Allegheny Mountains.
Range Most of Canada south in Midwest to ne Montana, Nebraska, Iowa, n Illinois, n Indiana, Ohio, Pennsylvania, West Virginia, and through s Appalachian Mountains.
Discussion The smallest living carnivore, the Least Weasel is seldom seen and rarely trapped, and does not appear to be common in any part of its range. Previously known as Mustela rixosa, it is now considered to be the same species as the European Least Weasel (Mustela nivalis). Like other weasels, it turns white in the northern part of its range, with some individuals remaining brown all winter from southern Michigan southward. White individuals have been seen, however, in Pennsylvania, Ohio, Indiana, and other areas in the middle part of its range. The Least Weasel may be abroad day or night, any time of the year. It moves over its home range of less than 2 acres (.8 ha) in search of prey, investigating every hole or crack and frequently standing on its hindfeet to scan for predators or prey. It may have several temporary dens scattered over its range. It will den in the abandoned burrow of another small mammal, such as a mouse, gopher, or ground squirrel, adding a lining of mouse hair to the rodent's grass nest. This species can run very fast, up to 6 mph (10 km/h). It feeds almost entirely on meadow voles, chasing them along their runways, and is small enough to chase mice inside their burrows. Pouncing on its prey, the weasel wraps its legs around the victim and kills it with a swift bite at the base of the skull. Occasionally it eats shrews, moles, birds (including eggs and nestlings), and insects. Despite legend, weasels do not suck blood, but do often lick blood from their prey. Weasels will kill more than they can eat when prey is available, caching the excess in the side passages in their dens. The Least Weasel consumes about 40 percent of its own weight per day. Male Least Weasels are sexually mature at eight months and females at four months, though they seldom breed in their birth year. Males and females remain separate except during the breeding season. Like other mustelids, the Least Weasel has the characteristic anal glands used for defense and for marking territory. When disturbed, it gives a shrill squeaking call, and it may hiss when threatened. Foxes, cats, hawks, and owls are the Least Weasel's chief predators.
