any of various small, mouselike rodents of the genera Lemmus, Myopus, and Dicrostonyx, of far northern regions, as L. lemmus, of Norway, Sweden, etc., noted for periodic mass migrations that sometimes result in mass drownings.
Someone needs to be the first lemming over the cliff.
But the degree to which the mammals relied on their caches varied with changes in lemming abundance.
Finally, on a somewhat related note, be glad you're not a lemming.
The pine barren's frog, northern bog lemming, golden-crowned kinglet and lynx are adapted to living in the acidic habitat.
Bogs shelter many rare animal species, including the spotted turtle and southern bog lemming.
British Dictionary definitions for lemming
any of various volelike rodents of the genus Lemmus and related genera, of northern and arctic regions of Europe, Asia, and North America: family Cricetidae. The Scandinavian variety, Lemmus lemmus, migrates periodically when its population reaches a peak
a member of any large group following an unthinking course towards mass destruction
C17: from Norwegian; related to Latin latrāre to bark
"small arctic rodent," 1607, from Norw. lemming, from O.N. lomundr "lemming." Perhaps from Lapp luomek. Fig. sense (in reference to their mass migrations that sometimes end in plunges into the sea) is from 1959.