Japanese weasels are small carnivorous mammals native to Japan. Their fur is orange-brown with darker markings on the head. The fur on the throat is usually white in color. Females in this species are smaller than males.
Japanese weasels are native to Japan where they occur on the islands of Honshū, Kyūshū, and Shikoku. They typically live in mountainous or forested areas near water. They can also be found in grasslands, villages, and suburbs, but try to avoid big cities.
Japanese weasels are solitary and very territorial animals. They will aggressively defend their home range, especially dominant males. When cornered or very frightened, these animals produce a smelly secretion from an anal gland to scare away predators. Japanese weasels are skilfull hunters and will chase down their prey by any means. They will run down through the tunnels, climb trees, or even swim. Anywhere prey can go, they will follow. The scientific name of Japanese weasels means “to carry off mice.” When searching for mouse runways, these little animals will investigate holes and crannies in rocks, trees, and undergrowth. They use their sensitive nose and ears to locate prey. Japanese weasels are active during the day and night. They live in dens in hollow logs and tree stumps and make their hole cozy with soft feathers or grasses.
Japanese weasels are polygynous which means that one males mates with more than one female during the breeding season. These animals breed from early May to late June. After the gestation period of about 30 days, the female gives birth to 2-12 kits, but usually 5 or 6. The mother nurses her young within 8 weeks. After this time they are fully weaned and independent. Both males and females become reproductively mature at one year of age.
The native population of the Japanese weasel disappears from lowlands in the western part of Japan. The main threat is habitat loss due to residential and commercial development. These animals may also suffer from competition with the introduced Siberian weasel.
The IUCN Red List and other sources do not provide the Japanese weasel total population size. Currently, this species is classified as Near Threatened (NT) on the IUCN Red List and its numbers today are decreasing.
Due to their carnivorous diet, Japanese weasels help control populations of rodents and other small animals.