Erlend Haarberg / Norway lemming (Lemmus lemmus) calling on spring snow, Vauldalen, Norway, May

Erlend Haarberg / Two Norway lemmings (Lemmus lemmus) interacting on spring snow, Vauldalen, Norway, April

Erlend Haarberg / Norway lemming (Lemmus lemmus) swimming, Sweden, May

Bengt Lundberg / Norway lemming on snow {Lemmus lemmus} Sweden

Kerstin Hinze / Steppe Lemming / Vole (Lagurus lagurus). Captive,

Kerstin Hinze / Steppe Lemming / Vole (Lagurus lagurus). Captive,

Erlend Haarberg / Norway lemming (Lemmus lemmus) on spring snow / ice, Vauldalen, Norway, April

Sergey Gorshkov / Lemming (Lemmus lemmus) Agapa River, Taimyr Peninsula, Siberia, Russia

Jeff Wilson / 'Lemming Crossing' sign on main road to the Eureka weather station, Ellesmere Island, Nunavut, Canada, June 2008. Taken on location for BBC series, Frozen Planet, Summer

Jeff Wilson / Arctic Lemming (Dicrostonyx torquatus) on Tundra, Ellesmere Island, Nunavut, Canada, June 2008. Taken on location for the BBC series, Frozen Planet.

Jeff Wilson / Arctic Lemming (Dicrostonyx torquatus) on Tundra, Ellesmere Island, Nunavut, Canada, June 2008. Taken on location for the BBC series, Frozen Planet.

Bryan and Cherry Alexander / American arctic lemming (Dicrostonyx groenlandicus) on Arctic Tundra. Baffin Island, Nunavut, Canada.