In 1532, the geographer Jacob Ziegler of Bavaria proposed the theory that the creatures fell out of the sky during stormy weather and then died suddenly when the grass grew in spring.

Driven by strong biological urges, some species of lemmings may migrate in large groups when population density becomes too great. They can swim and may choose to cross a body of water in search of a new habitat. In such cases, many drown if the body of water is an ocean or is so wide as to exceed their physical capabilities.

It is not a deliberate mass suicide, in which animals voluntarily choose to die.

the corresponding leftovers of predatory frenzies: lemmings do not explode