Don't mess with this lemming. Its ferocious calls and multicoloured fur set it apart from most other small rodents, which are typically docile and drab.
Malte Andersson from the University of Gothenburg in Sweden has been testing whether Norwegian lemmings (Lemmus lemmus), like the one in the video above, deter predators by warning them of their aggressive nature with their shrieks.
The vivid markings on the fur also indicate to predators that this critter isn't for eating. Having such warning colours – a phenomenon known as aposematism – is common in insects, snakes and frogs, but unusual in herbivorous mammals.
This combination of hues made the lemmings easier to spot than their plain-looking neighbours, grey-sided voles.
When a predator, played by humans in Andersson's test, is far away, these lemmings prefer to go unnoticed, he found. But when predators get closer, to within a few metres, these lemmings were much more likely to give out a warning call than their browner relatives.
The conspicuous colours, aggressive calls and threatening postures together let predators know to expect a fight, and potentially damage, if they attempt to eat a Norwegian lemming. In contrast with the voles, these lemmings aggressively resist attacks by predatory birds.
Journal reference: Behavioral Ecology and Sociobiology, DOI: 10.1007/s00265-014-1868-7
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