Wood lemming
The high female sex ratio may be an adaptation against local mate competition and inbreeding during population low points.This migratory behavior was exaggerated in popular stories about lemmings; innumerable numbers dash down the hillsides and fall down over rocks into the sea, only to drown.[6] Lemmings gravitate towards areas with abundant cover from predators, i.e., holes provided by decomposed trees, stumps, and mossy rock.[6] The wood lemming is well adapted to live in cold climates due to its high thermogenic capacity, thermal insulation, and nonshivering thermogenesis.[7] Compared to other voles, lemmings drink greater amounts of water, which may be why they seek moister areas in the spring and summer.