At first glance these slender weasels appear at a serious disadvantage when it comes to keeping warm in the winter. They have practically no body fat, and relatively little fur in their winter coats, but an ermine has several unique features and strategies to make up for it.
For one, their coat turns from brown to white each winter, allowing them to be nearly invisible as they move through a snow white landscape. Their tail has a black tip on the end, which functions as a decoy luring any potential predators to strike there, rather than a more vulnerable part of the body.
To make up for a lack of body fat and extra fur, they generate body heat with their cranked up metabolism. Essentially, they turn their body into a heater, eating up to 6 times a day. When ermines do take time to rest, it needs to be in an insulated location. The den of a chipmunk or vole they just killed fits the bill perfectly. Another tactic ermines are known to employ is actually lining the inside of a log or den with the fur of their victims to keep warm.