While many people believe that lemmings commit mass suicide when they migrate, this is not actually the case. Lemmings will often migrate in large groups and as a result some lemmings will occasionally be pushed off cliffs or drowned in bodies of water simply by the press of their compatriots. The myth of lemming mass suicide is long-standing and has been popularized by a number of factors. It is usually stated that the main source of the belief in the suicide myth was propagated by The Walt Disney Company documentary White Wilderness which includes footage of lemmings running head-long over a ledge. However, the filmmakers contrived this scene.[3]
Due to their association with this odd behavior, lemming suicide is a frequently-used metaphor in reference to people who go along unquestioningly with popular opinion, with potentially dangerous or fatal consequences. This is the theme of the video game Lemmings, where the player attempts to save the mindlessly marching mammals from walking to their doom
http://en.wikipedia.org/wiki/Lemming
ACTUAL FOOTAGE OF THESE RODENTS KILLING THEMSELVES



http://www.youtube.com/watch?v=xMZlr5Gf9yY
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video link
AN ARTICLE SAYING THE LEMMINGS WERE PUSHED OFF
http://www.drbeetle.com/lemming.html