Ornithology Unit 2 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