The northern collared lemming or Nearctic collared lemming (Dicrostonyx groenlandicus), sometimes called the Peary Land collared lemming in Canada, is a small lemming found in Arctic North America and Wrangel Island. At one time, it was considered to be a subspecies of the Arctic lemming (Dicrostonyx torquatus). Some sources believe several other species of collared lemmings found in North America are actually subspecies of D. groenlandicus.[2]
It has a short chunky body covered with thick grey fur with a thin black stripe along its back and light grey underparts.[citation needed] It has small ears, short legs and a very short tail.[citation needed] It has a pale brown collar across its chest.[citation needed] In winter, its fur turns white, and it has large digging claws on its front feet.[citation needed] It is 14 cm (5.5 in) long with a 1.5 cm (0.59 in) tail and weighs about 40 g (1 oz).[citation needed]
It is found in the tundra of northern Canada, Alaska and Greenland. A disjunct population is also present on Wrangel Island in Siberia; this population was formerly considered its own species, the Wrangel lemming (D. vinogradovi).[3][4][5]
It feeds on grasses, sedges and other green vegetation in summer, and twigs of willow, aspen and birches in winter.[citation needed]
Predators include snowy owls, gulls, wolverines, the Arctic fox and the polar bear.[citation needed]
Female lemmings have two or three litters of four to eight young in a year. The young are born in a nest in a burrow or concealed in vegetation.[citation needed]
It is active year-round, day and night.[citation needed] It makes runways through the surface vegetation and also digs burrows above the permafrost.[citation needed] It burrows under the snow in winter.[citation needed] Lemming populations go through a three- or four-year cycle of boom and bust.[citation needed] When their population peaks, lemmings disperse from overcrowded areas.[citation needed]