The Mountain weasel is a small, active predator that lives in high-altitude environments of Asia. Its summer coat consists of gray to gray-brown fur with some light yellow, while the winter fur is more of a dark yellow with some brown. In both coats, the underbelly is a pale yellow to creamy white. The upper head between the muzzle and ears is usually darker gray-brown. The tail may be more rufous than the back. The summer fur is gray to gray-brown with some light yellow. The lips are white and the chin has grayish-brown vibrissae.
Mountain weasels occur from Kazakhstan, Tibet, and the Himalayas to Mongolia, northeastern China, and southern Siberia. They are most common, however, is Ladakh, India. They live in primarily mountains, as well as rocky tundra and grassy woodlands.
Mountain weasels are generally nocturnal, but may also hunt during the daylight. They are excellent climbers, runners, and swimmers; their long bodies and short legs allow them to be very agile. When not active these small predators usually rest in rock crevices, tree trunks, and abandoned burrows of other animals or the animals they previously hunted. Mountain weasels are solitary and only come together to breed. They communicate with each other visually and vocally. They use sounds to warn of possible predators, to protect their territories, and when mating. When threatened, Mountain weasels emit a loud chirring sound and excrete a foul, pungent odor from their anal glands.
Mountain weasels are strict carnivores. They primarily feed on pikas and voles but also muskrats, rabbits, ground squirrels, small birds, lizards, frogs, fish, and insects.
The mating system of Mountain weasels is unknown, but it is suggested that they are polygynous like other species in the same genus. Polygynous groups usually consist of one male and multiple females. Mountain weasels breed once a year. Males fight vigorously for access to females. Mating usually occurs in February or March, and the young are usually born in May. The gestation period is 30-49 days, but these periods of gestation and birth can be altered because the animal is capable of delayed implantation until resources are available to maintain the pregnancy and feed the young. The litter size is 1 to 8 kits. They are born altricial, require nourishment, and depend on the mother; their eyes are closed, and their fur is not well developed. Lactation lasts about 2 months, and after weaning, the kits become independent but remain with their littermates until fall. Young are able to breed in the following season when they are just under a year of age.
The main threats which face Mountain weasels include habitat change due to human development and traffic on roads, which can reduce their population. Overgrazing by cattle, goats, and sheep causes the prey of the Mountain weasel to diminish because their hiding spots and food are reduced.
The IUCN Red List and other sources don’t provide the number of the Mountain weasel total population size. Currently, this species is classified as Near Threatened (NT) on the IUCN Red List and its numbers today are decreasing.
Praying mainly on pikas and voles, Mountain weasels have an important ecological role in reducing or limiting the population numbers of these rodents.