(Mustela erminea), a valuable fur-bearing animal of the family Mustelidae. In summer the fur is rusty brown and in winter, snow-white; the tip of the tail is black year-round. The male’s body is about 25 cm long (the female’s is somewhat shorter), and the tail reaches 10 cm.
The ermine is widely distributed in Europe, Asia, and North America; it is found in almost the entire territory of the USSR, from the coast of the Arctic Ocean to approximately the deserts of Middle Asia. The animal lives most often in river valleys, near lakes or reed thickets, but it is also found in forests, coppices, mines, and fields. Sometimes the ermine settles near human dwellings. It is extremely mobile: it swims and climbs trees. Its prey is usually murine rodents and small birds. Sometimes it attacks larger animals, such as the caper-caillie or rabbit.
The ermine mates during the second half of the summer, but the embryo begins to form at the end of the winter; the young are born in the spring. Ermines usually produce five to eight offspring (sometimes more). They are born blind and almost bare; their eyes open within approximately 30 days; by the end of the summer the young reach sexual maturity. In years when there are few rodents, the number of ermines decrease. They are useful in eradicating murine rodents. Ermines are hunted (their fur is used for decoration).