Its scientific name is Myodes lemmus, and closely related species are found in northern Siberia and in Arctic America.
Lemmings weigh from 30 to 112 g (1.1 to 4.0 oz) and are about 7 to 15 cm (2.8 to 5.9 in) long.
In general appearance the lemmings are more like miniature short-eared, yellowish rabbits or pikas than like mice.
Lemmings do not hibernate through the winter.
Lemmings subsist wholly upon vegetable food, dwell in nests made of bark, grass, etc., in some sheltered nook, and do not hibernate but force their way about underneath the snow in search of moss, lichens, sprouting woody plants and other edible things.
Like all rodents, lemmings have a high reproductive rate and can breed rapidly when food is plentiful.
Lemmings are very prolific, rearing two broods of four to six young annually, and hence every few years they become so numerous that the mountains can no longer support the bordes. At such times, occurring at irregular intervals of several years according to circumstances, an exodus takes place and great numbers of lemmings descend from the mountains and spread over the lowlands.
There the easier climate, more abundant food and absence of enemies, permit a still further multiplication of the lemmings, so that by the following season the little animals have increased into a plague. They wander more and more widely, overrun and damage, or sometimes wholly devour crops, gardens and meadows, and make themselves a destructive nuisance. Such an invasion is felt more severely in the narrow and fertile valleys of Norway than in the broader and more forested spaces of Sweden. At such a time concerted measures are devised to kill them off, carnivorous mammals and birds flock to the feast and epidemic diseases often break out among them. Spreading with a restless energy for travel, the lemmings overcome or attempt to overcome all obstacles and heedlessly plunge into lakes too large or rivers too swift to be crossed. When the remnants of the host reach the sea many of them boldly swim out in their ignorance of its magnitude and are drowned. Such overruning of the country by lemmings is not known in Arctic Asia or America, where different conditions exist.
Lemmings
