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Name: Riley
Status: student
Age: 14
Location: N/A
Country: N/A
Date: 4/21/2003

Why do birds fluff their feathers when they are cold?

The most obvious reason might be to allow their feathers to keep them warmer than otherwise by trapping more air as an insulator...but...this is a guess on my part and nature has a way of sometimes hiding secrets behind the obvious.

Peter Faletra

Fluffing their feathers makes the layer of still air trapped between their feathers thicker. That makes it a better insulator, more able to keep their body heat inside.

Richard E. Barrans Jr., Ph.D.
PG Research Foundation, Darien, Illinois


The protein material of which feathers are made allow heat to be transferred by conduction and, as such, it is not quite as good as an insulator as is air. When the bird fluffs it feathers, it loosens them so as to trap air between the fibrils. The combination of trapped air and feathers is a much better insulator that feathers alone.

As you may already know, wet feathers stick together very tenaciously. That is why down-filled garments and blankets must be thoroughly dried and tumbled after washing in order to loosen the feathers and restore the "loft" of the insulating material.

ProfHoff 647

Bird feathers work as insulation by trapping small pockets of air that are separated from the outside and warmed by the bird's body heat from within. The more they are fluffed out the more air they trap. That is why a down sleeping bag is rated by "loft" the amount of air that is trapped within the down feathers in the bag, the higher the loft, the more air, and greater insulation.

J. Elliott

HI Riley,

Birds fluffing create tiny air pockets between their feathers. Air is a really great insulator. So they are simply insulating themselves against the cold. Ever sleep under a down comforter? Very light, very fluffy, very warm. Same theory.

Martha Croll

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