The picture is tragic, and perhaps a bit comic. Consumed by pure instinct, thousands of small arctic rodents rush towards a cliff and commit suicide by leaping into the ocean below. It's the legend of the lemmings, and it's pure nonsense: it was fabricated by a couple of filmmakers and broadcast widely by Disney. In this clip from CBC's Midday, biologist Charles Krebs replaces the suicide theory with other ways to explain sudden drops in lemming populations.

• The legend of suicidal lemmings can be traced to one source: a 1958 nature documentary called White Wilderness. The film was shot in Alberta, and since the province is not lemming territory, the lemmings were imported.
• A few dozen rodents were filmed to simulate migration, then transported to a cliff and herded to their deaths in the river below.

• The film, which was three years in the making, depicted numerous animal species of the north. It won a 1959 Academy Award for Documentary (Feature).
• According to a 2003 article in the Pittsburgh Post-Gazette, Disney doesn't defend the practice. "Although we have been unable to accurately determine exactly what techniques were used in producing White Wilderness in 1958, standards and techniques for filmmaking were very different 40 years ago," said Rena Langley, a spokesperson for Walt Disney World.

• The myth has been thoroughly debunked by scientists, newspapers, magazines and a 1982 episode of CBC's The Fifth Estate.
• In truth, lemming populations crash due to a combination of factors. According to a 2003 article in the journal Science, Finnish scientists found that lemming numbers increase exponentially every four years. Predator numbers then also increase, leading to a crash in lemming populations.

• Dr. Charles Krebs, interviewed in this clip, is a professor of zoology at the University of British Columbia. His research focuses on animals of the Arctic, particularly lemmings and snowshoe hares.

Medium: Television
Program: Midday
Broadcast Date: March 24, 1992
Hosts: Steve Paikin, Tina Srebotnjak
Guest(s): Charles Krebs
Duration: 6:24