Lemming

The lemming (binomial name Lemmus lemmus) is a small rodent native to northern Scandinavia and Arctic regions. Measuring 2 to 6 inches in length, lemmings are famous for their migratory patterns during which, under pressure from increasing populations, they migrate in large numbers across the terrain. The idea that they deliberately throw themselves off cliffs committing mass suicide, long considered a myth, actually has a basis in fact, though the deaths are certainly not deliberate, merely the result of overcrowding and effectively running out of land. In the 1950s Walt Disney made a film called White Wilderness which featured thousands of lemmings apparently jumping off cliffs into the icy sea, but it later transpired that they had been pushed.