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. Vane
2. Rachis
3. Barb
4. Afterfeather
5. Hollow shaft,
calamus
Feathers are made of keratin
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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 Rheinhartia ocellata 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
Feather
evolution
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
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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