Lemming, << LEHM ihng, >> is the name for a number of small, plump animals related to the mouse. Lemmings inhabit cold, northern parts of the world. A well-known kind, the Norway lemming, lives in Scandinavia. 
Lemmings grow from 31/2 to 7 inches (9 to 18 centimeters) long, including the short tail. Most kinds of lemmings have grayish and brownish fur. The animals eat plant materials. They make bowl-shaped nests of grasses and sedges (grasslike plants). Wild lemmings survive for about two years. Such animals as birds, weasels, and foxes eat lemmings.
About every four years, lemming populations in the wild decline greatly. Numbers then increase to levels similar to those before the declines. Scientists believe severe winter weather, diseases, and behavioral changes due to stress may help trigger these extreme die-offs. Some people believe that large groups of lemmings throw themselves from cliffs. But lemmings do not deliberately kill themselves.
