The mountain weasel (Mustela altaica), also known as the pale weasel, Altai weasel or solongoi, primarily lives in high-altitude environments, as well as rocky tundra and grassy woodlands. This weasel rests in rock crevices, tree trunks, and abandoned burrows of other animals or the animals it previously hunted. The home range size of this animal is currently unknown. Geographical distribution for this species lies in parts of Asia from Kazakhstan, Tibet, and the Himalayas to Mongolia, northeastern China, and southern Siberia. The most common area for this species, however, is Ladakh, India. The conservation status, according to the IUCN, is near threatened because it is considered to be in significant decline and requires monitoring mainly because of habitat and resource loss. Description Sexual dimorphism is slight in the Altai weasel. The male body length from head to base of the tail is about , with the tail adding about . Males can weigh . Females are slightly smaller, with their head and body lengths measuring around , with their tails adding , and they weigh about . This species undergoes seasonal molts during the spring and autumn. The 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 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. Reproduction Overall, these animals are thought to be solitary animals except when mating. The mating system for these animals is unknown, but other species in the same genus are polygynous. Polygynous groups usually consist of one male and multiple females. The mountain weasel breeds 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; the female can breed and the egg is fertilized, but the egg does not attach to the endometrium in the uterus to continue pregnancy until resources are available to maintain the pregnancy and feed the young. The litter size is one