Why Are Colorful Birds Colorful?
One bird watcher I met many years ago says he got started in birding because he asked a simple question ("What's that black bird with red wings?") and was surprised by the answer provided to him by a local National Audubon Society Member: "Why, that's a Red-winged Blackbird."
If only identifying all birds were so easy! However, case in point, once people begin studying birds, they often ask us what makes colorful birds colorful. This article will address this question.
Most colors in birds can be boiled down into about 13 basic colors, including black, white, yellow, red, blue, and green. Given that many bird species exhibit a variety of colors in combination with one another, and recognizing that there are over 9,000 species of birds in the world, one can begin to appreciate the patience needed to identify birds by sight alone.
The color we see in birds is visible to us because: (1) the bird's feathers contain pigments; and/or (2) the structure of the bird's feathers is refracting light back to our eyes.
Let's talk about structure first. The blue color we see in birds like the Indigo Bunting, bluebirds, or jays results from incoming light being scattered by small air pockets in the feathers. More dramatically, iridescent colors in birds perform like a hologram: depending on the angle at which you view it, the color pattern may change. Doves, hummingbirds, and some blackbirds exhibit iridescent colors - which is the result of light being refracted in many directions by the structure of the feathers.
At least 3 different groups of pigments play a part in the coloration of birds. Colors ranging from yellow, to rusty-brown, or even black may be produced by tiny fragments of melanin in either the skin or feathers of birds.
In contrast, some of the brightest colors we see in birds (e.g., red, orange, or yellow) originate from a class of pigments called carotenoids. Interestingly, while birds are able to make their own melanin pigments; they must ingest carotenoid-containing seeds, berries, or fruits in order to develop their bright red, orange, and yellow colors. Porphyrins (a third class of pigments) may produce red, green, or other colors and may be found in birds such as owls.
This spring, as the birds begin to migrate north and burst into full song, don't be surprised if you find yourself staring longer at these feathered treasures now that you know what they're made of. There actually is some truth to the old saying, "Now there's a bird of a different feather!"