The steppe polecat (Mustela eversmanii), also known as the white or masked polecat, is a species of mustelid native to Central and Eastern Europe and Central and East Asia.It is listed as Least Concern on the IUCN Red List because of its wide distribution, occurrence in a number of protected areas, and tolerance to some degree of habitat modification.

[3] The steppe polecat is a nomadic animal which typically only settles in one area until its prey, mainly ground squirrels, are extirpated.

[4] It mates from March to May, and generally gives birth to litters of three to six kits, which attain their full growth at the age of two years.

It was considerably smaller than the present form, thus indicating polecats evolved at a relatively late period.

[8] As a species, the steppe polecat represents a more specialised form than the European polecat in the direction of carnivory, being more adapted to preying on larger rodent species; its skull has a stronger dentition, its projections are more strongly developed and its muscles of mastication are more powerful.

[15] The skull is heavier and more massive than that of the European polecat, having more widely spaced zygomatic arches and more strongly developed projections, particularly the sagittal crest.

[17] It has four pairs of teats and well-developed anal glands, which can produce a sharp-smelling liquid which is sprayed in self-defence.

[18] Overall, specimens exhibiting gigantism are more common than in the European polecat, and occur primarily in western Siberia, where they likely hybridise with Siberian weasels.

[19] The winter fur is soft and tall, with short, dense underfur and long, sparse guard hairs.

The tips of the guard hairs are blackish-brown or brown, forming a frosting effect over the yellow underfur.

The head is piebald, with the eye region and the upper side of the nose being covered by a brownish mask.

The summer coat is shorter and coarser than the winter fur, and is not as dense and close-fitting, with a more strongly developed ochreous or reddish tone.

During warm seasons, especially in areas rich in ground squirrels, aged polecats hold relatively stable territories until they have extirpated their prey.

Younger polecats are less sedentary, and will sleep overnight in the burrows of ground squirrels they have killed.

[4] The species does not usually dig its own burrow, instead using those of marmots, ground squirrels, hamsters, moles, voles, jerboas and others, after slightly widening them.

The eyes open after 28–34 days, and the kits become more active, to the point of attempting to tear apart prey whilst still relying on the mother's milk.

The kits begin to disperse from July or later, and attain sexual maturity at the age of 10 months.

Ground squirrels are its most frequent prey throughout the year; in warm periods, they are hunted on the surface, while in autumn they are excavated from their burrows.

Birds occasionally killed by the steppe polecat include grey partridges and willow grouse.

[6] The steppe polecat is weakly susceptible to sylvatic plague, tularemia and canine distemper.