Plumage
and its
Function in
birds
Basic distinction between:
Molt = feather replacement and Plumage = Feather coat
Basic (prebasic molt)
- renewed plumage postbreeding
Typically replace all feathers
after breeding and, often, before
onset of migration
Alternate (prealternate molt)
- breeding plumage
Typically partial replacement of
feathers in spring
Mite damage – can damage an individual's plumage during heavy
infestations & result in energy-loss via poor thermoregulation
…or loss of mates if plumage is involved in mate selection
Birds use three general types of pigments:
Melanins: are synthesized in animals.
These pigments are typically responsible
for the blacks, browns, and less striking
colors.
Porphyrins & Carotenoids: are responsible
for the reds and yellows and greens. They are
only synthesized by plants, and thus must be
consumed in the diet.
Great-tailed grackle
Barbules are layered with air bubbles
that create a diffraction/interference
pattern to reinforces selected
wavelengths while canceling others
The plumage of iridescent birds is
caused by reflectance from the sun
and amplification of certain wavelengths,
rather than using pigments.
Sunscreen applied
Broods from sunscreen-ed
males produce fewer sons
UV
Many birds have plumage characters that reflect UV light
Feather wear, as in this Snow Bunting,
which changes from a contrasting black
and white in the male to a less
contrasting, browner plumage after
breeding
What is the function of a bird’s plumage ?
- Stream-lining
- Thermoregulation
- Waterproofing
- Protection
- Camouflage
- Foraging
- Anti-predator behavior
What is the function of a bird’s plumage ?
Concealment of the eye
a b
c
d e
- Stream-lining
- Thermoregulation
- Protection
- Camouflage
- Foraging
- Anti-predator behavior
Detectability (%)
- Waterproofing
100%
50%
Distance to border
What is the function of a bird’s plumage ?
- Stream-lining
- Thermoregulation
- Waterproofing
- Protection
- Camouflage
-
Foraging
- Anti-predator behavior
American redstart wing-flicking
What is the function of a bird’s plumage ?
- Stream-lining
- Thermoregulation
Pygmy owls
- Waterproofing
- Protection
- Camouflage
- Foraging
- Anti-predator behavior
Sun bittern “eyespots”
Not all “color” need have a function
- Stream-lining
}
- Thermoregulation
- Waterproofing
- Protection
- Camouflage
- Foraging
- Anti-predator behavior
Color would have little role in
these functions …except which?
}
Color has a behavioral function
i.e., within species interaction
…so does color always have a behavioral function?
- Stream-lining
- Thermoregulation
- Waterproofing
- Protection
- Camouflage
- Foraging
- Anti-predator behavior
}
}
Color would have little role in
these functions …except which?
Color has a behavioral function
i.e., within species interaction
Structural coloration
What do birds have to COMMUNICATION ?
- Species recognition
- Individual identification
- Social dominance rank (age)
- Fitness (male quality)
- Attract mates
What do birds have to COMMUNICATION ?
- Species recognition
- Individual identification
- Social dominance rank (age)
- Fitness (male quality)
- Attract mates
Summary of results from Rohwer and Rohwer (1978) manipulation
experiments on subordinate Harris’ Sparrows
Look
dominant
Paint black
Inject testosterone
Both
Behave
dominant
Change in
status
Y
N
N
N
Y
Y
Y
N
Y
Cheating is prevented b/c status is ultimately checked by escalation
If birds BOTH look dominant and act dominant
they can rise in status, whereas acting w/o looking
dominant they can’t
What do birds have to COMMUNICATION ?
- Species recognition
- Individual identification
-
Social dominance rank (age)
Breeding
Female
- Fitness (male quality)
- Attract mates
Non-breeding
First Yr Male
Breeding
Second Yr Male
American Redstart
What do birds have to COMMUNICATION ?
- Species recognition
- Individual identification
- Social dominance rank (age)
- Fitness (male quality)
- Attract mates
What do birds have to COMMUNICATION ?
- Species recognition
Red-billed Quelea
- Individual identification
- Social dominance rank (age)
- Attract mates
Plumage Saturation (%)
- Fitness (male quality)
Northern Cardinal
Plumage Hue
- Species recognition
- Individual identification
- Social dominance rank (age)
- Fitness (male quality)
- Attract mates
These two types of traits are not limited to (colorful) plumage…what else is there?
Displays
Vocalizations
And in very special cases….bowers