New discovery: Lemming defence strategy

The latest scientific news reveals that lemmings bark to warn of their bite. 

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Lemming

Many a fanciful story has been told about the Norwegian lemming. Some of them, such as the one about mass suicidal tendencies, have little to do with reality. But others turn out to be true.

In the 1970s, Swedish biologist Malte Andersson found that Norwegian lemmings are under-represented in the diet of long-tailed skuas compared with other rodents from the same habitat. He wondered whether their striking orange, white and black fur warns predators to steer clear, much like the black and yellow patterns of many insects.

Four decades on, Andersson has gathered more evidence. He’s now shown that, when a predator approaches, Norwegian lemmings actually draw attention to themselves with loud barks and screams. In contrast less colourful Alaskan brown lemmings, and other Norwegian rodents, flee and hide from danger. For such brashness to be effective, there must be a good reason for predators to think twice about attacking. It’s unlikely that the lemmings are toxic – predators will happily eat dead ones – but they are very good at defending themselves in other ways.

“When you approach, they often race towards you and scream, before lunging and trying to bite,” Andersson told BBC Wildlife. “They can keep a small predator at bay. Weasels, stoats, long-tailed skuas, crows and ravens do sometimes take lemmings, but they have respect for them.”

Andersson suspects that the Norwegian lemming’s warning colours are what make their famous mass migrations so conspicuous. “It probably means that they can move in the open during the day at lower risk than other rodents,” he said.

Warning colours are rare in mammals, and the Norwegian lemming is the only confirmed case among rodents. Andersson suspects there may be another, though. European hamsters stand on their back legs when attacked, which exposes black underparts decorated with white dots. “That’s a very unusual coloration in animals,” he said.

Source Behavioural Ecology and Sociobiology

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