Ornithology Unit 2
Feathers
Feathers
• Feathers are unique structures made of a protein called keratin’
• The keratin is different from that found in the scales of reptiles (argues against evolution)
Vaned Feathers
Contour and Flight
Contour Feathers
• Body covering feathers
• Mainly used for aerodynamics
• Also help as an outer shell for insulation
Flight Feathers
• Used for flight• They have very little
insulating function• There are two types,
remiges and retrices
Remiges
• Flight feathers of the wing
• They are long, stiff and aerodynamic
• Coverts – smaller feathers that overlap the remiges and cover gaps between them
Primaries
• Remiges that attach to the hand bones
• Provide forward thrust on the downstroke
Secondaries
• Attach to the ulna• Found at the inner
wing surface• Sometimes modified
for display purposes
Retrices
• Flight Feathers of the tail
• Attach to pygostyle- fused vertebrae at the base of the spine
• Used for steering and braking
Special Remiges
• Owls have special barbs on flight feathers that make them fly silently
• Some birds, like the woodcock, have narrow outer primaries that make a trilling noise used in mating displays
Special Retrices
• Elaborate tails of peacocks and other birds can be a handicap in flight
• Some are used for bracing in woodpeckers and similar birds
Down Feathers
• Down feathers are soft and fluffy
• Usually lack a rachis • Barbs and barbules
extend directly and loosely from the calamus
• They trap air and work well to insulate
Semiplumes
• Intermediates between contour and down feathers
• Have a large rachis with loose vanes
• Enhance insulation and fill out the contours of body plumage
Filoplumes
• Hair-like feathers that monitor the movement of adjacent vaned feathers
• Extend beyond contour feathers on songbirds
• Monitor speed and aid in aerodynamic adjustments
Bristles
• A stiff, tapered rachis with a few basal barbs
• Specialized for sensory and protection
• Many insect eating birds have them around their mouths
The Feather Coat
• Each bird has thousands (swans – 25,000, songbirds 2,000-4,000)
• Usually the feather coat weighs 2-3 times as much as the skeleton
• Are attached to skin, but not evenly
• They’re found in dense patches called feather tracts
Feather Care
• Uropygial Gland – “preen gland” that secretes oil they apply to the feathers. It makes them waterproof and keeps them from becoming brittle.
• Preening – repositioning feathers and applying oil
• May preen as often as once an hour when at rest.
Feather Growth
• Feathers are like our fingernails and hair – they’re dead
• New feathers grow from follicles
• -New feathers push old, worn feathers out of the follicle
Plumages
• Most birds have a distinct looking juvenile plumage (entire coat of feathers)
• Most birds will replace their plumage twice per year (called molting)
• In some species, the males will have different plumages for breeding and non-breeding seasons
• Molting is done gradually
Feather Colors
• Feather color either comes from biochrome pigments or structural colors
Biochrome Pigments
• These pigments come in three categories: melanins, carotenoids and porphyrins
• Melanins – make grays, black, browns and buff colors
Carotenoids
• Give yellow, orange, red and certain blue and green colors
• Most are derived from the diet of a bird
Porphyrins
• Give a bright brown or green color
• Glow a bright pinkish-red under ultraviolet light
Structural Pigments
• Account for many of the brightest feather colors
• Results from the feather structure scattering the light as it is reflected
• Usually results in an iridescent color
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