1. Feathers make birds unique and have many important roles in birds
Chapter 4 - Feathers

2. Feathers Feathers are protein structures
Beta (β)-keratin
Unique to reptiles and birds
Wide use of β-keratin in the reptilian and avian body
Wide use of feathers on the avian body
Wide variety of feather structure on a single bird
Wide variety of pigments in the feathers of this Blue-winged Warbler (Vermivora pinus)

3. Feathers There are some basic repeated parts across feather types
There are several types of feathers
Different duties on the bird
Different types of names for them

4. feathers
Remiges
Rectrices

5. Feathers

6. Feathers Vaned feathers most conspicuous
This is what you see all over the outside of the bird
These are important to flight
Flight feathers stiff
Lodged into the bone for strength
Vanes asymmetrical for ‘slicing’ through the air
Few bizarre alterations

7. FEathers

8. feathers Owls (Great Gray Owl, Strix nebulosa)
Diurnal or nocturnal hunters
Must be quiet!
Specialized barbs on leading edges of feathers
Reduces air turbulence
Feathers look fuzzy
Quiets down any sound
This is the largest species of owl in the United States, stands over 2 ft tall, wing span of close to 6 ft.

9. Feathers
Tails have functional uses in day to day life, can display cumbersome extravagance (when you want a mate), and some things you think are tails, aren’t

10. Feathers Tail feathers attach at pygostyle
Pygostyle allows greater range of tail movement

11. Feathers
Various modifications of feathers and their uses

12. Feathers
How are feathers arranged on most birds?

13. Cardinalis cardinalis nestings, can see tracts

14. Greater roadrunner Geococcyx californianus
Will elevate feathers to both lose heat and to warm up on cold desert mornings
Has black stripes on skin for heat absorption
Greater roadrunner Geococcyx californianus

15. Feathers Feathers – like our hair and skin, dead structures
Will wear down over time and possibly break
Less effective in their various jobs when worn
Studies where feather replacement has been stopped result in:
Increased metabolism (heat loss)
Reduced mate attraction
Reduced waterproofing
Reduced survival
Feathers replaced annually, at least, via molt
Molt initiated by hormones
Typically, the end of breeding signifies initiation of molt

16. Feathers Feathers grow from follicles, much like hair
One follicle can produce multiple feather types over lifespan
New feathers grow under old feathers, pushing them out
This is an energy and nutrient expensive process!

17. Feathers
Note the little tube-like structures around the base of the white feathers, these are feather sheaths

18. Feathers Steps of feather follicle development (A-C)
Follicle without a feather (middle picture)
Growing feathers (D-E)

19. Feathers Molt is a, relatively, orderly process
Most species lose tail and flight feathers in sequence
Some notable exceptions – ducks
Typically do not want to impair ability to fly or thermoregulate
Most species molt one time/year (basic molt)
Some have additional molts (non-breeding and breeding plumages) (alternate molt)
Juveniles may alter aspects of molt to save energy
Wings and tails often not replaced on first molt
Some confusing terminology associated with molt

20. Feathers During feather growth pigments will be deposited into feather
Structural protection
Anti-bacterial properties
Ultraviolet protection
Camouflage
Sexual selection
Scarlet Tanager (Piranga olivacea) males have both melanin and carotenoid pigments in their feathers

21. Carotenoid coloration
Feathers
Melanin coloration
Carotenoid coloration
Note, white areas have no pigments
Here carotenoids color the bill too

22. Structural coloration
Feathers
Porphyrin pigments
Structural coloration
These colors will be reflected light, typically off a melanin coated surface (Satin Bowerbird, Ptilonorhynchus violaceus )
The brown colors of the Red-crested Bustard (Eupodotis ruficrista) are not melanin

23. Ultraviolet reflectance
Eastern Bluebird (Sialia sialis)
Some structural colors also have a UV reflectance signal
We can’t see UV, however birds can
Much research has shown that UV reflectance influences mate choice and co-varies with quality

24. Feathers Feathers have to be taken care of daily
Oils and waxes from preen gland are applied
Antimicrobial, can alter UV absorbance, contain pheromones
Preening of feathers (nibbling at them with bill)
Removal of ectoparasites
Realignment of feathers
Bathing in water
Dust bathing
Deters parasites
Stops itches

25. Gathering preen gland secretions
Feathers
Preen gland above tail
Gathering preen gland secretions

26. Feathers
Proposed steps of evolution are all seen in developing feathers in extant birds, or in individual types of feathers
Possible evolutionary steps for feather development

27. Tufted Titmouse, Baeolophus bicolor
Feathers
Archaeopteryx
Tufted Titmouse, Baeolophus bicolor

28. feathers