Feather Structure Insulates

white goose feathers lay on the ground between fallen leaves and grass

Biological Strategy

Canada goose

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Protect From Temperature

Many living systems function best within specific temperature ranges. Temperatures higher or lower than that range can negatively impact a living system’s physiological or chemical processes, and damage its exterior or interior. Living systems must manage high or low temperatures using minimal energy, which often requires controlling responses along incremental temperature changes. To do so, living systems use a variety of strategies, such as avoiding high or low temperatures, removing excess heat, and holding heat in. Insulation is a well-known example of managing low temperatures by retaining heat using thick layers of hair, fur, or feathers to hold warm air next to the skin.

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Birds

Class Aves (“bird”): Eagles, hawks, sparrows, parrots

Birds are evolutionary engineering marvels. They are descended from dinosaurs, but are far from our idea of heavy, scaly reptiles. Of the specific adaptions that set them apart, most notable is flight—although some mammals can fly, birds take the prize for abundance in the skies. Many birds have hollow, lightweight skeletons and specially-designed wings to help them stay aloft. They also have feathers made of keratin that help them stay warm, attract mates, and improve navigation and aerodynamics in flight. In contrast to their dinosaur ancestors, they lack true teeth and have replaced them with specialized beaks and bills.

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Down feathers of geese insulate through special architecture.

Image: Alan Wilson /

Canada Goose, Colony Farm Regional Park, Port Coquitlam, British Columbia. 2005

Image: Fuzzy Thompson /

“Feather keratin occurs in a ‘b-sheet’ configuration which differs from the a-helices that occur in mammalian keratins. . . We have measured the properties of individual down feathers from ducks, geese and penguins and found that their properties are similar to flight feathers and, indeed, the man-made s used in artificial insulation fibres. The message is that the architecture of down feathers is probably more important than material properties in determining their advantages over synthetic materials. . .Recently, we have begun to explore the toughness of feather keratin by using instrumented clippers and scissors. The fracture toughness of β-keratin has proved to be very high, around 10 kJ m-2.” (Bonser 2007)

Illustration comparing the structure of keratin in goose down to the hair of a small mammal. The helical structure of the keratin in the down appears to be looser while the mammal hair has a tighter coil. mammal.

Comparison of keratin structure in down feathers and mammal hair.

Last Updated August 18, 2016

References

Journal article

Web page

Mechanical properties of keratin

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Reference

Journal article

Cameron, G. J.; Wess, T. J.; Bonser, R. H. C.

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