Animals' survival instincts put to test this winter

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D.S. Pledger
February 9, 2014

On these cold mid-winter nights, we humans simply turn up the heat, pull the covers up over our heads and listen to the wind rattle the bedroom window as we drift off to sleep.

On the other side of that thermopane, however, birds and animals must deal with the brutal weather as they try to survive until morning.

The chickadee that flits around your feeder during the day often roosts in an evergreen when the sun goes down. It locks its feet around a branch and rests its head and neck on its back while it buries its bill in its shoulder feathers.

This would be an uncomfortable position for humans, but it’s not for birds. Thus arranged, the chickadee’s neck muscles are relaxed and its eyes are protected from the cold.

Mourning doves and pigeons settle their heads down into their shoulders with their bills pointing forward, but all birds puff up their feathers to create as much dead air space next to their bodies as possible.

Another thing that helps preserve a bird’s body heat is the fact that their legs are covered with insulating scales. They can also constrict the blood flow to their extremities, making the exposed foot and leg lose even less heat.

Sometimes a bird will perch using only one leg as it shields the other with its feathers. Small birds like titmice and chickadees may also sleep communally, crowded together in a tree cavity or empty birdhouse to keep warm (special “roosting boxes” are sold for this purpose).

During extreme cold, the ruffed grouse will spend the night in a snow bank. As evening approaches, the grouse will fly into a drift and burrow down under a foot of snow. It will remain there for as long as 16 hours insulated not only by its feathers, but also by the snow.

Conditions must be right for this, though. Occasionally the bird misjudges the softness of the snow and breaks its neck while diving into a wind-packed or ice-covered bank.

Like the grouse, rabbits have also learned to use snow’s insulating qualities. The morning after a heavy fall they sometimes will be found sitting in “forms,” which are simply miniature snow caves created when they let the falling snow completely encase them.

Squirrels usually have a cavity in a tree to retreat to when the weather gets nasty, although the less fortunate ones might spend the winter in their open twig and leaf nests.

When they sleep they curl up in a ball and cover themselves with their big bushy tails, much like a human might use a comforter.

Beavers might have the best solution of all for dealing with the cold. They spend the winter months tucked away in their lodges that are insulated not only by a thick layer of mud and sticks, but also by a foot or more of snow. In this windless environment where the temperature hovers just over the freezing mark, they keep warm by sharing their body heat—heat that also helps to warm the lodge.

One animal that doesn’t seem to make special allowances for the cold is the dim-witted porcupine. It passes nights (and days, too, for that matter) wherever it happens to be, which is usually in a tree where it eats bark in all kinds of weather.

When temperatures plunge below zero, though, porkies do seek refuge in a den, which is often a cavity at the base of a tree or under a vacant cabin. Like some other animals, they have been known to huddle together to share body heat (but one would assume they do so very carefully).

Whatever allowances wildlife can make for the cold, they can only do so much. A particularly brutal winter like the one we are experiencing will inevitably take a toll. Come spring, only the fittest will still be here.


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