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Feathers. JodyLee Estrada Duek , Ph.D. With many illustrations, links from Dr. Gary Ritchison http://people.eku.edu/ritchisong/avian_biology.htm.
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Feathers JodyLee Estrada Duek, Ph.D. With many illustrations, links from Dr. Gary Ritchison http://people.eku.edu/ritchisong/avian_biology.htm
birds are distinguished primarily by feathers; feathers are responsible for two very important features of birds: warm-bloodedness (endothermy) and flight. Parts of a feather:1. Vane2. Rachis3. Barb4. Afterfeather5. Hollow shaft, calamus
Feathers are made of keratin • Keratin is a protein • Similar to our hair or nails • Grow in specific areas or tracts • Number of feathers depends on size, ecology • About 1/3 of total feathers are on head • Some hummingbirds under 1000, some swans 25,000 in winter • A wild pheasant Rheinhartiaocellata has tail feathers over 5 feet long • A birds feathers weigh about twice as much as their dried bones (or more)
Feather Morphogenesis • Animations of Feather Morphogenesis
1. Flight Feathers • Wing feather • Tail feather
2. Contour Feathers • Provide shape, contour • Coloring • Protection
3. Down Feathers • Lack barbules • Provide insulation
Scanning EM of downy and pennaceous barbules of an American Crow
Other feather types: 4. Semiplume • Halfway between contour and down, supply insulation
5. Filoplume • Usually small, may have a sensory purpose • Only a few barbs, usually at the tip
6. Bristle • Only a very few barbs, very stiff • Occur around eyes and mouth • Probably protective function
7. Powder Feathers • Grow continuously • Tip disintegrates • Barb breaks into a fine powder • Probably helps with cleaning (e.g. in herons) • Scattered throughout plumage of most birds • Not well understood
Water repellent • The surface structure of most feathers provides a contact angle that repels water
No feathers • Brood patches are areas where feathers fall out during incubation • Area has many capillaries to provide extra warmth to eggs for rapid development Robin Carolina wren www.hiltonpond.org