Plumageand its

Function in birds

Basic distinction between:

Molt = feather replacement and Plumage = Feather coat

Basic (prebasic molt)- renewed plumage post- breeding

Alternate (prealternate molt)- breeding plumage

Typically replace all feathers after breeding and, often, before onset of migration

Typically partial replacement of feathers in spring

…M

OLT….

Why replace feathers?

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.

The plumage of iridescent birds is caused by reflectance from the sun and amplification of certain wavelengths, rather than using pigments.

Great-tailed grackle

Barbules are layered with air bubblesthat create a diffraction/interference pattern to reinforces selectedwavelengths while canceling others

Many birds have plumage characters that reflect UV light

UV

Sunscreen applied

Broods from sunscreen-ed males produce fewer sons

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 ?

- Stream-lining

- Thermoregulation

- Waterproofing

- Protection

- Camouflage- Foraging

- Anti-predator behavior

Concealment of the eye

a bc

d e

100%

50%

Distance to border

Det

ect

abili

ty (

%)

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

- Waterproofing

- Protection

- Camouflage

- Foraging

- Anti-predator behavior

Sun bittern “eyespots”

Pygmy owls

What is the function of a bird’s plumage ?

- Stream-lining

- Thermoregulation

- Waterproofing

- Protection

- Camouflage

- Foraging

- Anti-predator behavior

Hooded PitohuiMELRYID BEETLE

Not all “color” need have a function

- Stream-lining

- Thermoregulation

- Waterproofing

- Protection

- Camouflage

- Foraging

- Anti-predator behavior

} Color would have little role inthese functions …except which?

}Color has a behavioral functioni.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 inthese functions …except which?

}Color has a behavioral functioni.e., within species interaction

Structural coloration

What is the function of a bird’s plumage ?

What else ?

COMMUNICATION

- Stream-lining

- Thermoregulation

- Waterproofing

- Protection

- Camouflage

- Foraging/Anti-predator behavior

This male Lyrebirdhas something to

communicate

- Species recognition

- Individual identification

- Social dominance rank (age)

- Fitness (male quality)

- Attract mates

What do birds have to COMMUNICATION ?

Badges of Status

The size of the black bibin several species of sparrows signals dominance rank andeliminates undo fighting between males

“Private”

“Sergeant”

“Captain”

- Species recognition

- Individual identification

- Social dominance rank (age)

- Fitness (male quality)

- Attract mates

What do birds have to COMMUNICATION ?

Paint blackInject testosterone

Both

Lookdominant

Behavedominant

Change instatus

Y N N

N Y NY Y Y

Summary of results from Rohwer and Rohwer (1978) manipulation experiments on subordinate Harris’ Sparrows

Cheating is prevented b/c status is ultimately checked by escalation

If birds BOTH look dominant and act dominantthey can rise in status, whereas acting w/o looking dominant they can’t

BreedingFemale

- Species recognition

- Individual identification

- Social dominance rank (age)

- Fitness (male quality)

- Attract mates

What do birds have to COMMUNICATION ?

Non-breedingFirst Yr Male

BreedingSecond Yr Male

American Redstart

- 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

What do birds have to COMMUNICATION ?

Plu

mag

e S

atu

rati

on

(%

)

Plumage Hue

Red-billed Quelea

Northern Cardinal

- 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