Beyond Your Backyard - Birds Are Truly Foul Weather Fowls

By Kimberly J. Epp

Many of our Spring migrants have already returned - and over last weekend and much into this week, we had one of the biggest snowfalls of the year. Is it the last snowfall? In Saskatchewan, one can never be too sure!

You may be worried about the birds, specifically the waterfowl. In fact, local rescues received many calls last weekend about Canada Geese surrounded by snow. They were, however, using the snow as insulation. There is plenty of new grass coming up for food, and open water for them to swim on. So, just how is it that birds feet stay warm in winter and how do they remain warm and dry in and under that snow?

Canada Goose sitting on nest, snow actually insulating her as she keeps her eggs warm. (Photo via the Prairie Wildlife Rehabilitation Centre.)

While feathers are excellent insulators, the legs and feet of most birds lack this protective covering. For this reason, legs and feet are a major source of heat loss for birds. Birds’ feet are mostly bone and tendons, so, unlike mammals, they have a limited supply of nerves, blood vessels, or muscles to freeze. Their feet are also covered with scales which, like our hair, aren’t living tissue and thus are less susceptible to freezing. Don't forget, birds are direct ancestors of dinosaurs!

Many birds, including the winter birds that spend their time here year-round, waterfowl, gulls, and penguins, etc. have what is called "counter-current heat exchange system". Arteries and veins in their legs run parallel and in contact with each other. As the warm blood of the arteries enters the legs, the heat is transferred to the returning cold blood of the veins. This allows the cooler blood to get heated up somewhat before reentering the body, which minimizes the heat lost to the cold air. Under very warm conditions, the countercurrent heat exchange mechanism can be bypassed.

During extremely cold weather, heating the core takes less energy than heating the entire body. Birds such as chickadees can actually lower their body temperatures into a state of near hypothermia as they huddle together at night in order to help them survive the long winter nights. The energy from the food they ate all day has to last all night to keep them warm, so when it is very cold, energy is conserved by going into near hypothermia.

Birds exhibit behavioral adaptations as well, such as standing on one leg and tucking the other among breast feathers, reducing by half the amount of unfeathered limb surface area exposed. You may often see this with Canada Geese...a flock of them standing in a field, using just one leg as they warm the other. Also, by sitting down and covering both legs, even on ice, heat loss from limbs is minimized.

A real Black-capped Chickadee display shows how they huddle together in family groups to keep warm, sometimes even within the powdery fresh snow. (This photo is from the Wild Alberta Gallery at the Royal Alberta Natural History Museum.)

And that's where humans can actually cause a problem. If ducks, geese, swans or other waterfowl are sitting with their feet tucked up and people keep forcing them to move, then they can get frostbite.so, please just leave them be. Believe it or not, they are adapted to this crazy weather...but they do a better job weathering the storm without human interference.

Read more here about how birds and other wildlife survive the cold and snow:

The Tricks Wildlife Uses To Survive Deep Freezes

Epp is an Environmental Educator and writer and is also the Past President of the Moose Jaw Nature Society. She can be reached at kepp@shaw.ca or at (306) 681-3198 if you have a question about nature. Stay tuned for her Earth Day column on April 22nd, one you won't want to miss, on the nature of pandemics.