1. Feathers JodyLee Estrada Duek, Ph.D.
With many illustrations, links from
Dr. Gary Ritchison

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. Vane 2. Rachis 3. Barb 4. Afterfeather 5. 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 Rheinhartia ocellata 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

7. 1. Flight Feathers
Wing feather
Tail feather

9. 2. Contour Feathers
Provide shape, contour
Coloring
Protection

10. 3. Down Feathers
Lack barbules
Provide insulation

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

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

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

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

15. 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

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

17. 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