Least Weasel

The least weasel is the smallest member of Mustela. It has an extremely slender elongated body, very short legs, and a short tail without the black tip of a stoat. Upperparts are normally brown and the underparts white, divided by a fairly straight boundary. Northern and high-altitude animals may become entirely white in winter. Size, tail proportion, and coat pattern vary widely over its vast range, so the short unmarked tail remains the most useful distinction from an ermine when both wear white winter coats. (Wikipedia, general species account)

Least weasels occupy fields, open woodland, scrub, rocky ground, parks, and gardens. They specialise in pursuing mice, voles, hamsters, and gerbils through narrow tunnels, while also taking rabbits, birds, eggs, fish, and frogs. Existing holes are used for sleeping, storing prey, and raising young. Breeding occurs in spring and summer; females alone rear a litter averaging about six after a 34–37-day gestation. Mongolia's national mammal account reports the species as especially abundant in eastern steppe, the southwestern Khangai, around Ulaanbaatar, and in Mongol Daguur Steppe. (Wikipedia, general species account; Mongolian Red List of Mammals 2006)