Transcript Feathers - WordPress.com

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
CALIFORNIANUS
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
REFLECTANCE
Some
structural
color s 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