I was going to say lemmings
but it seems that's a misconception
Lemmings have become the subject of a widely popular misconception that they commit mass suicide when they migrate by jumping off cliffs. This urban myth became widespread after this behavior was shown in the Walt Disney documentary White Wilderness (film) in 1958. However, the animals in the film are not wild animals jumping off the cliff voluntarily, rather they were bought by the producers and pushed over the edge of the cliff. Instead of suicidal behavior, what explains the drastic fluctuations in population size are environmental factors such as whether the right kind of snow is available.
wth??? disney killed a whole bunch of animals by pushing them off a cliff, all for a fake nature documentary??