Poor little misrepresented rodents! Although lemmings do tend to migrate in large groups, they do not, in fact, engage in mass suicide (the only animal to do such a foolish thing would be the human animal). The “lemmings” stereotype is a complete myth, based in a stunt by D*sney in one of their animal kingdom movies (they needed something dramatic and so forced the lemmings off a cliff – nice!).
You can easily verify this by doing a web search on “lemmings suicide,” but here are details for the skeptical and lazy: www.snopes.com/disney/films/lemmings.asp
[Sorry that this isn’t much of a post, but it feels like a much-needed cultural correction.]