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Feathers: Essential Characteristics and Evolution in Birds

Explore the fascinating world of bird feathers, from their role in flight and endothermy to different types like down and contour feathers. Learn about feather morphogenesis and evolution, with insights into unique feather types. Discover how feathers provide warmth, protection, and water repellency in birds.

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Feathers: Essential Characteristics and Evolution in Birds

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  1. Feathers JodyLee Estrada Duek, Ph.D. With many illustrations, links from Dr. Gary Ritchison http://people.eku.edu/ritchisong/avian_biology.htm

  2. 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

  3. 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)

  4. Feather Morphogenesis • Animations of Feather Morphogenesis

  5. Feather evolution

  6. 1. Flight Feathers • Wing feather • Tail feather

  7. 2. Contour Feathers • Provide shape, contour • Coloring • Protection

  8. 3. Down Feathers • Lack barbules • Provide insulation

  9. Scanning EM of downy and pennaceous barbules of an American Crow

  10. Other feather types: 4. Semiplume • Halfway between contour and down, supply insulation

  11. 5. Filoplume • Usually small, may have a sensory purpose • Only a few barbs, usually at the tip

  12. 6. Bristle • Only a very few barbs, very stiff • Occur around eyes and mouth • Probably protective function

  13. 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

  14. Water repellent • The surface structure of most feathers provides a contact angle that repels water

  15. 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

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