Birds and Winter Weather

Birds and Winter Weather

How can ducks swim in the water during the winter and not get frostbite?

I remember the cormorant I saw in the river that flows through town one bitter December morning, when the temperature was about ten degrees, and the wind was howling from the Northwest. The wind chill was about zero degrees, but that didn't stop the cormorant. It flew up onto the pier and, in a distinctive cormorant custom, briefly spread his wings and faced directly into the wind.

I thought how cold and how on earth could it survive. You could ask the same question of gulls that, like ducks, also stand or swim in icy water during winter, or even of chickadees, cardinals, mourning doves and other land birds that can survive bitter cold in the northern winters. The answer is that there are many ways in which our hardiest birds adapt to the severe winter weather.

Let's start with the fact that birds have multiple layers of feathers that help them withstand the cold and maintain body temperature. When birds fluff up their feathers in the winter weather, that can double a bird's effective feather quantity, letting their plumage trap an insulating layer of warm air next to their bodies. It is as if you placed a quilt over your body.

Also, when birds preen these feathers daily, they remove the grime and other foreign matter that would erode this necessary defense. Also they scatter an oil that waterproofs the feathers for protection from the harsh weather. This oil is created by a gland near their tail and is rubbed over the feathers with its beak.

When the winds are blowing the strongest, gulls land on the ice or sand facing directly into the wind, so that it blows over and along the shape of their feathers, and does not fluff their feathers from behind.

Feathers do not protect the bird's bill, legs and feet. Their beak is made of a hard material similar to their toe nails and not that vulnerable to harm from the cold.

Legs and feet can expose a bird to damage. This is where a specially clever change allows many birds to survive in the cold, snowy, blowing winter months. Even when the legs and feet and the blood are in the icy water. Science calls this "counter current heat exchange."

"Counter current heat exchange" means that a large vein carrying warm blood from the bird's body into its leg separates into many smaller vessels. The vein carrying cooled blood back from the foot into the leg also divides into many smaller veins, which run alongside and between the blood vessels.

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