For the Birds: Why don't bird feet freeze?

Tuesday, February 2, 2016

Black-capped Chickadee fluffing feathers to keep warm layer of air next to body
Photo by Craig Kerns

By Christine  Southwick

Have you ever wondered how songbirds stay warm in cold weather, or why their feet don’t freeze to cold metal?

Songbirds have such a high metabolism that the small amount of blood which circulates thru their feet doesn’t remain long enough to freeze. And their feet are  mainly tendons and bones, not skin, so they don’t stick.

Songbirds have had a long time to evolve, and one of their adaptations has been how to deal with cold weather.

Bushtits flock to suet, and huddle together to stay warm on cold nights
Photo by Lyn Topinka

Some birds migrate to warmer areas which have bugs and other nourishing foods.

A few, like Golden-crowned Kinglets, have adapted to being able to raise their metabolism which increases their core temperature while slowly processing their evening meal throughout the night.

Still others, like the Anna’s Hummingbird and a few songbirds can slow their heart-beat to a semi-hibernating, level, a process called torpor.

By far, the most universal method employed by songbirds is the fluffing of feathers to trap air close to their bodies, and thereby keeping a layer of insulated warmth.  [Note: goose bumps when you are cold would raise feathers if humans had them]. Down, a type of feather closest to a bird’s body, has the highest density, and is considered the best insulator in nature.

Having enough food during cold winter days is one of the most vital necessities. Calories equal heat, and a big meal before a cold night of roosting, and filling meals throughout the day can make the difference between survival and death.

Brown Creeper using crevice in large wildlife tree
 for storm protection and nesting  Photo by Scott Carpenter

Rains and winds are actually more dangerous than cold temperatures. To survive the chill from these, birds need to find protective shelter.

Keeping wildlife trees with holes for birds to rest in from wind, rain, fog, and snow can be as important as food. Evergreen trees like cedars, pines, and firs (the larger the better), plus evergreen shrubs like rhodys and huckleberries, will protect large numbers of birds. Brush piles, and even Himalayan blackberries provide areas free from most of the wind, and from frost.

Nectar in hummingbird feeders is often enjoyed by chickadees and Townsend’s Warblers when quick energy is needed (I leave a couple of the bee guards off during the cold for their access).

You can help your wintering birds survive by offering suet, black oil sunflower seeds, high-energy shelled seed, liquid water. Provide as many evergreen trees and dense vegetation as possible to offer life-saving shelter.


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