The Color of Birds: pigments

There have been a couple of questions recently about how color is controlled in bird feathers, so I thought I would explain that with some examples from some of my bird photos.  One excellent explanation of coloration in bird feathers can be found at the Cornell Lab of Ornithology’s website:  http://www.birds.cornell.edu/allaboutbirds/studying/feathers/color/document_view

To summarize their information, the color of bird feathers is formed in three ways:  by pigmentation of the feather, by structural properties of the feather, or a combination of both.  This post is about just the pigment part of color production.

There are three basic contributors to feather pigmentation:  melanin, carotenoids, and porphyrins.

Melanin pigments give feathers a yellow-brown to black appearance, the density of color depending on the amount of melanin present.  The presence of the melanin or any pigment actually strengthens the feather, and so we often see birds with white wings and black wing tips (e.g., gulls, terns, and white pelicans).  However, melanin also makes the feather more susceptible to bacterial degradation, leading to frayed wing tips which are not good for the long distance flyers or aerial maneuvers.

White Pelican from Lac Qui Parle dam, Minnesota.

Carotenoids may be derived from plant compounds like the xanthophylls we see in yellow, orange, or red leaves in the fall or carotene we see in carrots.  They must be eaten by the birds as the feathers are growing in during a molt, and some are modified by the bird to produce a specific color.  Examples are the yellow of Goldfinches or the yellow and orange colors in some tropical tanagers and spring warblers.

Flame-colored Tanager in Boquete, Panama

Porphyrins are metalo-proteins synthesized from amino acids, like the heme protein in the hemoglobin of our red blood cells.  These pigments produce pink to red colors, and in combination with melanin pigments produce the rich reds, brown, and greens of some tropical bird species, as well as owls, pheasants, turkeys, and other fowl.

Male Quetzal in Bouquete, Panama.

QUIZ TIME:

What pigments produced the color in this Keel-billed Toucan?

11 thoughts on “The Color of Birds: pigments

  1. Ummm…all three?

    Great info, Sue. This helps explain the “color” diet formulas for various cage birds, like canaries, who wouldn’t be eating the variety of foods they do in the wild, I guess. But then, it makes me wonder…if the tanager wasn’t getting enough carotenoids, would his coloring fade? Or change tints, somewhat?

    You are a good researcher! I really love your whole blog. One of my very favorites I’ve found here. Kudos!

    • I know that plants can synthesize secondary compounds that produce color (like the xanthophylls and chlorophyll in leaves. Perhaps fungi do the same. Sorry, I am unfamiliar with color production in fungi, although I certainly enjoyed looking at your photo essay on all the colorful ones you found.

  2. So, if the gold of the Goldfinch is diet-related, what foods do they eat that have the necessary compounds to give them their bright yellow coloration…and why do the females not have as bright of colors if it is diet-dependent…are they eating less of certain seeds?

    • Good questions, Adam. It must be more complicated than mere diet, because then, color would vary throughout the seasons, as some foods become more (or less) available. Perhaps like with the canaries I mentioned, the addition of these color agents intensifies the bird’s general coloration? Still confused, here. Maybe my eensy brain is more adapt to recognizing birds by color and pattern than understanding the science behind it. Eeep.

      • Ever the good student Adam, with good questions. I think that male hormones also play a role in determining the amount of yellow in the feathers after the spring molt.

      • Adam, I wasn’t able to find specific foods that contribute to Goldfinch yellow feathers, but here is a quote from Chipper Woods Bird Observatory,

        “The intense yellow plumage of the male is produced by carotenoid pigments such as leutin, zeoxanthin, and beta-carotene derived from plant materials in the bird’s diet. It is important that these pigments be available in the spring diet when the birds are replacing their contour feathers.”
        (http://www.wbu.com/chipperwoods/photos/goldfinch.htm )

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