Short Tailed Weasel - Ermine

Weasel Family

Classification: Non-game Wildlife Species

Other Names: Ermine, stoat

Status: Winter pelts of value when fur prices are high.  Unprotected predator.

Mustela erminea

Order: Carnivora
Family: Mustelidae

Identifying Characteristics: Of the three North American weasels is intermediate in size and one of the smallest carnivores in the world.  Males distinctly larger than females.  During summer fur is dark brown with white underparts, white feet, and white line down hind legs.  Molts to white during winter, except black tip on tail.

Total length: 7 to 13 inches.  Weight: 1 to 6 ounces.

Habitat: Inhabits brushy or wooded areas, usually not far from water.  Tends to avoid dense forest.  Prefers areas with high densities of small mammals.  Most abundant in ecotones.

Food Habits: Although short-tail weasels prey on a variety of small mammals and birds, they specialize in hunting voles.

Life History: Mostly nocturnal but will hunt during the day.  Active throughout the year.  Dens in ground burrows, under stumps, rock piles, or old buildings.  Breeds during summer; 8.5 to 10 month gestation; delayed implantation; young born April or May; one litter per year of 4 to 13 young.

Similar Species: Long-tail weasel - larger, longer tail.  Least weasel - smaller, short tail, no black tip on tail.  Mink - larger, uniform color.

The short tailed weasel (Ermine) is noticeably smaller, with a shorter tail, and varies from 8 to 14 inches long with a 4 1/2 inch tail. They weigh from 1 1/4 to 5 ounces and are 2 to 3 inches high.

It has a long, slender, muscular body with short legs. The head is small, with beady eyes, small ears and a pointed nose. They move with quick movements and a graceful, bounding gait. Weasels change color with the seasons, and there is no color difference between the sexes. All the senses are well developed in the weasel.

In summer, the short-tailed weasel is dark brown on the back and legs. The chin, throat and undersides of the legs are white or a light yellow. In winter, it is entirely white, sometimes with yellowish stains on the lower abdomen. The tail has a black tip year round.

Life Cycle
The short-tailed weasel females mature at 3 to 4 months and males mature at about one year. The breeding season is in July. There is a period of delayed implantation with a gestation period of 9 to 10 months. The period of active pregnancy is 17 to 23 days.

Litter sizes varies from four to thirteen, with an average of six to eight. The young are born in April or May in nests constructed in underground dens or hay piles. Mouse nests and burrows are often used and heavily lined with fine grass and mouse fur. The male begins to bring food to the den about 1 month after the young are born. The young are weaned at the end of 5 weeks and are able to hunt for themselves by 7 or 8 weeks of age. The family stays together until late summer and then disperses. The life expectancy of weasels is short, probably less than a year, although they are capable of living as long as 6 years.

Weasels prey on small rodents such as mice, rats, voles, hares, rabbits, and chipmunks. They also take shrews, birds, birds eggs, frogs, bats, insects, earthworms and may occasionally kill domestic chickens.

The weasel hunts by tirelessly and persistently investigating every small hole, crevice, bush or rock pile it encounters. They will track prey by following their scent trails and generally attack prey by ambushing and pouncing on it. They are very quick and kill by piercing the base of the skull with their teeth. The weasel frequently kills more than it can eat and often caches leftover food. The weasel can consume up to one third of its own weight in a 24 hour period.

Weasels are curious, alert and bold. They are persistent hunters who seldom remain long in their dens and may be abroad hunting at any hour, although they are usually most active at night. Weasels are active year round. Weasels occasionally hunt in pairs but, for the most part, are solitary except during breeding and rearing season. They are good swimmers and can also climb trees. All species emit a strong musk odor when alarmed, and the weasel may stamp its feet when annoyed. Weasels may mark their trails with droppings. Home ranges very from 30 to 400 acres.

Weasel populations often cycle with mouse populations. Several parasites can infect weasels, such as guinea worm and kidney worms. These probably have little impact on the population.

Weasels are subject to predation from hawks, owls, foxes, coyotes, dogs, cats and man.

In agricultural areas, weasels are more common due to the practice of storing grain which provides ideal conditions for mice.

Weasels prefer woodlands or open country with hedgerows, thickets or fence rows. They are usually found near water but are not semi-aquatic as is the mink. They frequent stone piles, brush heaps, wood piles, hay stacks, log piles and old abandoned buildings.

The short-tailed weasel inhabits brushy or wooded areas, usually not far from water. It tends to avoid dense forests. 

The dens of weasels are shallow chambers about 6 inches underground with two to three entrances and are lined with mouse fur and grass.

Economic Value
The fur of the short-tailed weasel was once reserved for use by royalty. The fur of the short-tailed weasel is fine and of good quality and is used in garments, lining and trim.

Weasels play an important role in helping to control rodent populations.

  Best Management Practices