Perhaps, it is one of the most successful and blood-thirsty predators of Neocaenic Europe. This species has wide life area: from southern woodlands up to dense coniferous woods and northern tundra. Length of the body is up to 30 cm, a tail - up to 20 - 25 cm. Forepaws are short, back ones are longer and brawny: the animal can jump from branch to branch on distance up to 5 meters. Claws are not involving, but sharp. The head is short, jaws can be opened widely. The top canines have the wide basis, they are similar to slightly bent blades, jutting out from the closed mouth. Summer wool is brown with pale cross strips, tip of the tail is dark, stomach is white. Winter wool is thick, white, tip of the tail is black, as at an ancestor of the present species - Holocene hermin (Mustela erminea). The animal lives on trees, frequently goes down on the ground. Its usual prey contain birds, small animals and cubs of large herbivores - any prey which the predator can kill. The beast attacks prey, creeping to it under covering of branches. It can prey ground animals, jumping on them from above, catch birds in flight by exact jump, forcing down by paws 2 - 3 birds at once for one jump. It differs by the might: animal can drag off on the tree sizable catch (weighting as the predator itself). The behavior of this animal in the beginning of winter is original: when the first steady frosts has become settled, the animal gathers stocks of tar cushats and other prey in "pantries" - hollows of old trees. The animal protects "pantry", in hungry time at unsuccessful hunting eats the frozen prey prepared earlier. The constant refuge is made only by the female before birth of posterity. At the end of spring it gives rise to 5 - 6 cubs in deep hole or the hollow of an old tree. The young growth develops quickly: in 2 days cubs begin to see clearly, in 2 weeks they already actively move in shelter and at the age of 1,5-month leave shelter and some time hunt together with mother. At the age of 2,5 - 3 months young animals leave from territory of mother and search to themselves for the constant place for life. Sexual maturity at females is in 1 year, at males - in 1,5 years. Life duration is till 12 years.