Lemming

Lemming — Lemmings are small rodents, usually found in or near the Arctic, in tundra biomes. Together with the 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 the rats, mice, hamsters, and gerbils.

Lemmings weigh from 30 to 112 grams (1-4 oz) and are about 7 to 15 centimetres (2.75-6 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. 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 utilising 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 in good seasons.

There is little to distinguish a lemming from a vole. Most lemmings are members of the tribe Lemmini (one of the three tribes that make up the subfamily).

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 that their natural habitat cannot provide.

Lemmings of northern Norway are one of the few vertebrates who reproduce so quickly that their population fluctuations are chaotic, rather than following linear growth to a carrying capacity or regular oscillations. It is unknown why lemming populations fluctuate with such variance roughly every four years, before plummeting to near extinction.

While for many years it was believed that the population of lemming predators changed with the population cycle, there is now some evidence to suggest that the predator’s population may be more closely involved in changing the lemming population.