Lemmings scare off predators by emitting a very loud bark, an extremely ferocious bite, and giving the false impression it is poisonous with its gold colors, says a Swedish researcher.
This ferocious behavior is unique among small rodents, Professor Malte Andersson, from the University of Göteborg in Sweden, wrote in the journal Behavioral Ecology and Sociobiology (citation below).
The Norwegian lemming (Lemmus lemmus), which is common in northern Scandinavia and the Kola peninsula in Russia, has yellow flanks, a white breast, chin and cheeks, a red-brown back, and a large black patch on its head, neck and shoulders.
The Norwegian Lemming is much more colorful than other lemmings, which some predators see as a signal of possible danger and stay away. (Image: Wikimedia)
It is rare for smaller rodents to protect themselves aggressively from predators. Norwegian lemmings are different. They think nothing of viciously fighting back aerial attacks from flying predators such as the long-tailed skua with bites, lunges and loud screams.
Consequently, this type of lemming, which belongs to a subfamily that includes musk-rats and voles, tends to catch the eye and ear much more than its cousins.
Aposematism is rare among mammals
Prof. Andersson carried out five field tests and noted that Lemmus lemmus’ remarkable traits can be ascribed to aposematism. Aposematism, also known as warning coloration, is a warning signal used by animals telling predators that they are not worth hunting because they have some form of defense, for example, they may be toxic.
Aposematism is extremely rare in herbivorous mammals, and is more common among frogs, snakes and insects.
In one of the experiments, eighteen volunteers were asked to spot Norwegian lemmings and grey-sided voles in their natural habitat. The observers found it much easier to pick out the lemmings.
Andersson noted in another test that brown lemmings only emitted anti-predatory warning calls when a potential predator (in this case a human) was near in 1 out of 39 instances.
Norwegian lemmings, however, gave warning shouts 36 times out of 110. Most adult and small juvenile Norwegian lemmings screamed out when Prof. Andersson was within five meters of them. When he was at a distance of at least 10 meters, the animals fled silently to shelter or froze, relying on their ability to remain hidden in their natural habitat.
Many predatory birds avoid Norwegian lemmings
The Norwegian lemming’s yellow, white and black colors plus its shouts make it immediately distinguishable from other rodents that live nearby, which are brown and grey and flee silently away without putting up a fight.
Yellow, white or black is a classic warning coloration, which some types of birds avoid instinctively.
According to Prof. Andersson, the Norwegian Lemming’s coloration and calls are often useful at close range, when the mammal is likely to be discovered even if silent. They tell the predator that the rodent will fight back if attacked.
“The Norwegian lemming combines acoustics with visual conspicuousness, probably to reduce its risk of becoming prey.”
Prof. Andersson believes that such warning coloration may help explain why the long-distance movements of Norwegian lemmings are so conspicuous.
Citation: Andersson, M. (2015). “Aposematism and crypsis in a rodent: antipredator defence of the Norwegian lemming,” Behavioral Ecology and Sociobiology. DOI 10.1007/s00265-014-1868-7.
Video – Ferocious Norwegian Lemming scares away predator