Lemming on snow covered ground.
A lemming is a small rodent, usually found in or near the Arctic, in tundra biomes. Lemmings are subniveal animals, and together with voles and muskrats, they make up the subfamily Arvicolinae (also known as Microtinae), which forms part of the largest mammal radiation by far, the superfamily Muroidea, which also includes rats, mice, hamsters, and gerbils.
Description and Habitat[]
Lemmings weigh from 30 to 110 g (1 to 4 oz) and are about 7 to 15 cm (3 to 6 in) long. They generally have long, soft fur, and very short tails. They are herbivorous, feeding mostly on leaves and shoots, grasses, and sedges in particular, but also on roots and bulbs. At times, they will eat grubs and larvae. Like other rodents, their incisors grow continuously, allowing them to exist on much tougher forage than would otherwise be possible. Lemmings do not hibernate through the harsh northern winter. They remain active, finding food by burrowing through the snow and using grasses clipped and stored in advance. They are solitary animals by nature, meeting only to mate and then going their separate ways, but like all rodents, they have a high reproductive rate and can breed rapidly when food is plentiful.
Behavior[]
The behavior of lemmings is much the same as that of many other rodents which have periodic population booms and then disperse in all directions, seeking the food and shelter their natural habitats cannot provide. The Norway lemming and brown lemming are two of the few vertebrates which reproduce so quickly that their population fluctuations are chaotic, rather than following linear growth to a carrying capacity or regular oscillations. It is not known why lemming populations fluctuate with such great variance roughly every four years, before numbers drop to near extinction. Lemming behavior and appearance are markedly different from those of other rodents, which are inconspicuously colored and try to conceal themselves from their predators. Lemmings, by contrast, are conspicuously colored and behave aggressively towards predators and even human observers. The lemming defense system is thought to be based on aposematism (warning display).
For many years, the population of lemmings was believed to change with the population cycle, but now some evidence suggests their predators' populations, particularly those of the stoat, may be more closely involved in changing the lemming population.