Wild Profile: Meet the least weasel

Published: October 6, 2020

A white least weasel in winter, against a snowy background By Vitaly Ilyasov/Shutterstock

The least weasel has a name that makes total sense. The tiny critter—barely bigger than a mouse, with a short tail—is the world’s smallest true carnivore. “True” or “obligate” carnivores are species that must eat meat to survive. (Other true carnivores include cats, seals, and walruses.)

No wonder the wee predator is so ferocious, and, like other weasels, skilled at wrapping its body around mice and vole prey, then dispatching them with a bite to the neck or skull. The weasel uses stealthy-ness to its advantage. It hunts mostly after dark, slinking through leaf litter and in tall grass meadows, the better to avoid getting nabbed by birds of prey or foxes.

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A weasel’s skinny body has its advantages too, but heat retention isn’t one of them. That’s why these animals have a high metabolism, higher than a chunkier animal of the same weight. The least weasel, in particular, hunts for only a few hours a day, but eats between five to 10 meals. Gotta keep the engine stoked!

This weasel’s other stealth manoeuvre? Just like the Arctic fox and the snowshoe hare, the least weasel’s brown coat changes to white, sometime between September and November. The white fur allows it to camouflage, blending in with the winter snow. Unfortunately, in part because of climate change, during the chilly season, least weasels have become more vulnerable to predators. Because of declining snow cover, their coat colour can be mismatched to the landscape in some parts of Canada. Coat colour change is triggered by day length, not temperature.

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