Beringian Ermine

The stoat, or ermine, is a small mustelid of Eurasia and northern North America. It is similar to the least weasel in proportions and movement, but the tail is relatively longer, always more than a third of the body length. The eyes are round, black and slightly protruding, and the whiskers are long. Males are 18.7–32.5 cm long in the body with a 7.5–12 cm tail and average 258 g, while females are smaller, under 180 g. The name ermine is used especially for the pure white winter coat (Wikipedia, general species account).

It feeds on small mammals, especially rodents, and is a serious threat to ground- and hole-nesting birds. Numbers rise when a glut of food lets rodent populations boom. In the Northern Hemisphere mating is in April–July, and the young are born blind, deaf and toothless with fine white or pinkish down; males play no part in rearing them. In Japan, its presence is independently supported by the national species catalogue used for this guide.