Mustela sibirica can be found throughout eastern Asia, north to the Sea of Okhotsk, and south to Kwangtung in China. In the south they range west to the edge of Tibet and the Gobi Desert, and north of the Gobi extending to European Russia. They have also been introduced to many of the islands of Japan. (Xu et al.,1995; Honacki et al., 1982; Tate and Hamiliton, 1947)
In Taiwan, Siberian weasels are mainly found in secondary forests at elevations of 1400-1700m. Siberian weasels can also be found, in less abundance, in primary forest and coniferous plantations. The preferred terrain for this species varies from ridges with 13 degree slopes to areas near water with slopes up to 37 degrees. (Hai-Yin, 1999)
Mustela sibirica is pale brown on the back, gradually changing to a paler, yellowish brown below. The tip of the tail may be a darker shade of brown than the rest, but is not black. Siberian weasel males measure 280 to 390 mm in head and body length and 155 to 210 mm in tail length, they weigh from 650 to 820 grams. Females are slightly smaller, with a head and body length of 250 to 305 mm, tail length of 133 to 164 mm, and weighing 360 to 430 grams. Foot length measures from 6 to 7.2 cm. (Gittleman, 1985; Tate, 1947)
Males may fight over access to females during the breeding season (Nowak, 1999).
M. sibirica breeds yearly during the late winter and early spring. Several males may court a single female, and fights between males have been noted. (Nowak, 1999) The gestation period is about 29 days and births occur from April to June. Litters average 5 pups, and range in size from 2 to 12 pups. Offspring are altricial. Eyes open at one month of age, and weaning occurs at two months. (Nowak, 1999) The weaning age for M. sibirica is 56 days and sexual maturity is reached at about 2 years of age. (Gittleman, 1985)
Young Siberian weasels are cared for by their mother in her nest for several months. Their eyes open at about 1 month old and lactation lasts for almost two months. Young disperse from their mother's range in the fall. (Nowak, 1999)
A study of wild populations in Japan showed that the average longevity of Siberian weasels was about 2.1 years. The oldest weasels were found to be between 5 and 6 years old. One captive M. sibirica lived to be 8 years and 10 months old. (Mayagi et al., 1983)
Siberian weasels are nocturnal and crepuscular. With the exception of the association between mothers and their young, these animals are solitary. They maintain territories, although they are known to migrate in times of food shortages. They have been observed moving up to 8 km in a single night. (Nowak, 1999)
Siberian weasels, like many other members of the genus Mustela, are efficient and ferocious predators. They feed on rice-field rats (Rattus argentiventer) in the coastal areas of southern China. In parts of their range (Nakdong Estuary, Republic of Korea) Siberian weasels may feed on little terns (Sterna albifrons) and their eggs.
In the subtropical forests of Taiwan M. sibirica was found to feed on a variety of small mammals (shrews, rats, mice) and to switch to a more invertebrate diet (including beetles, grubs and other invertebrates) when small mammal populations were low.
They store prey for later consumption, especially for eating during the winter. In times of food shortages, they have been known to make mass migrations
(Xu et al., 1995; Soon-Bok et al., 1998; Wu, 1999; Nowak, 1999)
Siberian weasels, like their relatives, are capable of standing up to attackers that are larger than themselves. The primary predators of weasels are probably large raptors, such as owls and hawks.
Siberian weasels play an important role in controlling rodent and other small mammal populations in the ecosystems in which they live.
As predators, these weasels perform an obvious function in controlling small rodent population. However, in recent years researchers have found the anal-gland secretions of M. sibirica cause rice-field rats (Rattus argentiventer) to go into self-anointing behavior. As a result, Siberian weasels are being introduced into agricultural areas to help control populations of these rats. (Xu, 1995; Zhongjian et al., 1995) They are also important in the fur trade (Nowak, 1999).
Siberian weasels sometimes take domestic fowl.
M. sibirica is on CITES Appendix III for populations in India.
Recent studies of mitochondral DNA support the hypothesis that Mustela itatsi and Mustela sibirica (once thought to be the same species) are actually two distinct species. This same study has also revealed that a population of M. sibirica that was indroduced to Japan from Korea may be going through a genetic bottleneck. (Naoko et al., 1998)
Jason Kreutzer (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor), University of Wisconsin-Stevens Point.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
living in landscapes dominated by human agriculture.
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
parental care is carried out by females
union of egg and spermatozoan
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
An animal that eats mainly insects or spiders.
fertilization takes place within the female's body
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
found in the oriental region of the world. In other words, India and southeast Asia.
having more than one female as a mate at one time
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
places a food item in a special place to be eaten later. Also called "hoarding"
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
A terrestrial biome with low, shrubby or mat-like vegetation found at extremely high latitudes or elevations, near the limit of plant growth. Soils usually subject to permafrost. Plant diversity is typically low and the growing season is short.
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
Gittleman, J. 1985. Carnivore Life History Patterns: Allometric, Phylogenetic, and Ecological Associations. Washington, D.C.: Smithsonian Institution.
Hai-Yin, W. 1999. Is There Current Competition between Sympatric Siberian Weasels (*Mustela sibirica*) and Ferret Badgers (*Melogale moschata*) in a Subtropical Forest Ecosystem of Taiwan?. Zoological Studies, 38(4): 443-451.
Honacki, J., K. Kurman, J. Koeppl. 1982. Mammal Species of the World. Lowrence, Kansas: Allan Press.
Hong, S., Y. Woo, S. Higashi. 1998. Effects of Clutch size and Egg-laying Order on the Breeding Success in the Little Tern Sterna Albifrons on the Nakdong Estuary, Republic of Korea.. Ibis, 140(3): 408-414.
Mayagi, K., S. Shiraishi, T. Uchida. 1983. Age Determination in the Yellow Weasel, *Mustela sibirica coreana*. Journal of faculty, Agriculture. Kyushu University, 27(3-4): 100-114.
Nowak, R. 1999. Walker's Mammals of the World, Sixth Edition. Baltimore and London: The Johns Hopkins University Press.
Tate, G. 1947. Mammals of Eastern Asia. New York, New York: The Macmillan Company.
Xu, Z., D. Stoddart, H. Ding, J. Zhang. 1995. Self-anointing behavior in the Rice-field rat, *Rattus rattoides*. Journal of Mammalogy, 76(4): 1238-1241.