Plumage and 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 …MOLT….

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 bubbles that create a diffraction/interference pattern to reinforces selected wavelengths 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 b c d e 100% 50% Distance to border Detectability (%)

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 Pitohui MELRYID BEETLE

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 is the function of a bird’s plumage ? What else ? COMMUNICATION - Stream-lining - Thermoregulation - Waterproofing - Protection - Camouflage - Foraging/Anti-predator behavior This male Lyrebird has 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 bib in several species of sparrows signals dominance rank and eliminates 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 black Inject testosterone Both Look dominant Behave dominant Change in status Y N N N Y N Y 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 dominant they can rise in status, whereas acting w/o looking dominant they can’t

Breeding Female - Species recognition - Individual identification - Social dominance rank (age) - Fitness (male quality) - Attract mates What do birds have to COMMUNICATION ? Non-breeding First Yr Male Breeding Second 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 ? Plumage Saturation (%) 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