As we endure a week of unusually cold weather, below zero for days at a time, I find myself wondering how the animals survive. The yard has been very quiet. Animals have several strategies to survive the cold. One is migration. Check – those animals migrated months ago, some moving thousands of miles, while others moved to lower elevations or more protected habitats. Another strategy is hibernation. Check – the fat bear in the yard in October is hopefully blissfully unaware of this cold snap. Marmots at higher elevations actually hibernate about 200 days a year! There are other animals that enter a temporary state of torpor during extreme cold. They are not true hibernators, but when temperatures fall, their internal temperature drops and their metabolism slows to conserve energy. Animals that utilize this strategy include bats, songbirds, and rodents. Other adaptations include burrowing, huddling in groups, curling into a ball, and denning. Other animals grow thicker fur or denser feathers, while others build fat reserves. Some, especially birds and bees, shiver to stay warm.
There are also a few unusual animal adaptations. One is that of the wood frog in Alaska. They just freeze solid. It’s true. They have a special anti-freeze proteins in their blood that allows them to freeze without harm to cells and organs. Brrrrr.
Some insects possess this anti-freeze too, including the snow fly. But the snow fly has one other trick: if it senses crystals forming in a limb, they will self-amputate before the crystals can reach vital organs! It’s extreme, for sure, but it allows them to survive. On another note, the snow fly is one of the only insects that stays active throughout cold, snowy months.
While not as extreme, but equally interesting, some animals shrink their brain to save energy survive the cold. This is a response to the cold and food scarcity seen only in a few animals including the European mole, weasels, and the Etruscan shrew. The brain regrows when conditions are more favorable. Research suggests, though, that during the time when their brain is smaller they are operating on reduced mental capacity and tend to wander shorter distances in search of food.
It all makes me extremely grateful for my blankets, sweaters, hats, sox, thermals, gloves, and hot chocolate!