Rodents closely related to mice and voles. Lemmings are small (about 8 to 12 centimeters [3 to 5 inches] long) and brown or red in color. They have short tails, live underground, and eat grass, roots, and plant products. They breed often and quickly; females are capable of producing a litter of 9 young only 20 days after mating. Species of “true lemmings” (genus Lemmus) live in open, grassy areas of Norway, Canada, and the United States; other lemming genera include the Arctic (or collared) lemmings, the red-backed (wood) lemmings, and bog lemmings.
Many people believe that lemmings commit mass suicide by trekking to the sea and throwing themselves over cliffs to drown in the water; this is not true. True lemmings (genus Lemmus) have a population cycle that, every few years, explodes. When food supplies begin to run short, lemmings will migrate in large numbers in search of new feeding grounds. The Norwegian species of lemming will cross rivers and lakes in search of food, even if many of them drown in the process. They do not necessarily stop when they reach the sea, which may have given rise to the suicide legend.