ornithology unit 2 feathers. feathers are unique structures made of a protein called keratin’ the...

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