Ermine
Mustela erminea Linnaeus
Mustelidae
Including the tail, adult males reach up to about 30 cm, while females are slightly smaller. They inhabit Hokkaido, the Tohoku region and the Chubu region of Honshu. Their fur turns white in winter. Among weasels, they are a highly carnivorous species, feeding on mice and small birds. While they are not thought to attack adult ptarmigans, they are natural enemies of their eggs and chicks.