Many lemmings leave to find a new home, when they run out of food and space. Soon, millions of lemmings decide to follow the crowd. They go across the Arctic as a huge mass. Foxes and owls kill many of them. Some drown when trying to swim across rivers. It is often said that they fall off cliffs or even commit mass suicide, but that is an urban legend created by a Disney documentary ("White Wilderness", 1958) in which someone actually pushed the lemmings over the edge.