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Adaptations: Feathers

What are Feathers?
Feathers are an adaptation of reptilian scales. They are complex structures and in animals on earth at the present time are found only in birds. They range in size from 0.05 inch on a bird eyelid to the tail feathers of a male peacock (Pavo cristatus) that may be five feet long. In number they range from 1,000 on a hummingbird to 25,000 on a swan and generally comprise 15-20 percent of the weight of the bird. Feathers only develop in specific places of a bird’s skin. They are made of keratin, a protein that also composes a bird’s beak and claws.

What do Feathers Look Like?
The feathers most commonly seen are contour and down feathers. Contour feathers cover the body of a bird and have a strong, hollow shaft and network of hooks or barbules (see diagram). The contour feathers on the tail and wings are modified for flight. Down feathers are small and lie under the contour feathers. The purpose of these feathers is to insulate the bird from the cold and protect against sunburn.

How do Feathers Help Birds?
Feathers perform a variety of functions, such as flight, regulation of body temperature, protection of the body and skin, attraction of mates, waterproofing and highlighting differences between species or between males and females of the same species. Feather color can provide protection through camouflage to match their surroundings. Birds may also be darker on the top side and lighter below to provide camouflage in flight. Some birds pluck their own feathers to line their nest and keep their eggs and young warm.

Does a Bird Always have the Same Feathers?
Even though they are kept clean, feathers become worn and are usually replaced at least once a year. This process is called molting.

What Else should I Know About Feathers?
Birds must take care of their feathers so they can continue to fly and remain warm. Preening feathers spreads oils over the feathers and "re-hooks" the barbules.

- The study of feathers is plumology.

- Some dinosaurs had feathers.

- Some birds have feathers that absorb water, allowing them to swim easier below the surface of the water as they hunt fishes.

 - Bristles are stiff feathers found around the eyes and bill.

- Feathers show colors because of the pigments that they contain. Pigments are chemicals that reflect, refract or scatter light or that use a combination of these processes.

- State and federal laws prohibit possession of migratory bird feathers. You can purchase feathers legally for educational purposes at a craft supply store or in the craft section of other stores.