Feathers make birds unique and have many important
Feathers make birds unique and have many important roles in birds CHAPTER 4 - FEATHERS
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)
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
FEATHERS Remiges Rectrices
FEATHERS
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
FEATHERS
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.
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
FEATHERS Tail feathers attach at pygostyle Pygostyle allows greater range of tail movement
FEATHERS Various modifications of feathers and their uses
FEATHERS How are feathers arranged on most birds?
Cardinalis cardinalis nestings, can see tracts
Will elevate feathers to both lose heat and to warm up on cold desert mornings GREATER ROADRUNNER GEOCOCCYX CALIFORNIANU S Has black stripes on skin for heat absorption
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
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!
FEATHERS Note the little tube-like structures around the base of the white feathers, these are feather sheaths
FEATHERS Steps of feather follicle development (A-C) Follicle without a feather (middle picture) Growing feathers (D-E)
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
FEATHERS During feather growth pigments will be deposited into feather Scarlet Tanager (Piranga olivacea) males have both melanin and carotenoid pigments in their feathers § Structural protection § Anti-bacterial properties § Ultraviolet protection § Camouflage § Sexual selection
FEATHERS Melanin coloration Note, white areas have no pigments Carotenoid coloration Here carotenoids color the bill too
FEATHERS Porphyrin pigments The brown colors of the Red-crested Bustard (Eupodotis ruficrista) are not melanin Structural coloration These colors will be reflected light, typically off a melanin coated surface (Satin Bowerbird, Ptilonorhynchus violaceus )
Eastern Bluebird (Sialia sialis) ULTRAVIOLET REFLECTANC E 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
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
FEATHERS Preen gland above tail Gathering preen gland secretions
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
FEATHERS Archaeopteryx Tufted Titmouse, Baeolophus bicolor
FEATHERS
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