How Feathers Insulate
How do birds stay warm when it's so cold?
This story comes to you through a partnership between 爆料公社 and BirdNote, a show that airs daily on public radio stations nationwide.
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Written by Frances Wood
Imagine this Canada Goose paddling along on a cold winter day. Can you guess how many feathers cover this goose? Hundreds? Thousands?
A single Canada Goose has between 20 and 25 thousand feathers. A smaller bird like a sparrow or wren might have 7 to 10 thousand. Those feathers are uniquely designed to help the bird fly, shed water, or display distinctive markings. A great many feathers are the short, fluffy kind, the down, whose purpose is to insulate the bird from the cold.
Birds survive in sub-zero weather by fluffing their feathers, creating layers of air and feathers. Just a fraction of an inch of this insulation can keep a bird鈥檚 body temperature at 104 degrees, even in freezing weather.
People learned years ago how well goose-down insulates and began stuffing comforters, sleeping bags, and clothing with it. More recently, we鈥檝e developed artificial substitutes, but geese and other birds continue to get along just fine with the original material.
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Bird sounds provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York. Calls of the Canada Goose [3585] recorded by G.B. Renyard. Winter wind Nature SFX Essentials #02 recorded by Gordon Hempton of QuietPlanet.com. BirdNote鈥檚 theme music was composed and played by Nancy Rumbel and John Kessler. Producer: John Kessler. Executive Producer: Chris Peterson. 漏 2014 Tune In to Nature.org January 2014 Narrator: Michael Stein