By Mike Checkett
Plumage colors result from pigments and from the structure and reflective properties of feathers
The development of the feather and the remarkable variation in plumage among bird species are two of nature’s miracles. Feathers are the most distinctive characteristic of a bird and are among the most complex structural organs found in vertebrates. Feathers form the flight surface, improve flight efficiency, and provide exceptional insulation. And they come in an amazing array of colors, which helps birds differentiate species, attract mates, and avoid predators.
Scientists believe feathers are actually a modified version of the scales seen in reptiles, as these two structures have similar chemical composition. Hummingbirds have the fewest feathers (some species have less than a thousand), while some swans have more than 25,000 feathers, 80 percent of which are on the birds’ head and neck.
Feathers grow out of a follicle in the skin. Although highly vascularized (nourished by blood vessels) during growth, mature feathers are nonliving tissue, somewhat like human hair and fingernails.
Ducks have many types of feathers—stiff, glossy ones on the outside to give a water-resistant, streamlined contour, and fluffy down feathers under these for warmth. On the wings, large, stiff feathers form a flexible airfoil, while some feathers in the tail or crest may be enlarged, elongated, or elaborately colored.
Feather colors produce the familiar plumage patterns of each duck species. Birds display virtually every color imaginable, and waterfowl are no different. Colors result from pigments in the feather or from the structure or reflective properties of feathers.
Pigment colorization in birds comes from melanins, carotenoids, and porphyrins. Melanins occur as tiny bits of color in both the skin and feathers of birds. Depending on their concentration and location, melanins can produce colors ranging from black to reddish brown and pale yellow. Feathers that contain melanin are stronger and more resistant to wear. Carotenoids are produced by plants and acquired by eating plants or by eating something that has eaten a plant. Responsible for the bright yellows, reds, and oranges seen in birds, carotenoids can interact with melanins to produce colors like olive-green. Porphyrins are produced in the body and create a range of colors, including pink, brown, red, and green.
Structural coloration in bird plumage is especially important in producing blues, greens, and iridescence. Blues and iridescent colors are generally the result of fine feather structure. There are no blue pigments in feathers (check a feather lit from behind to see for yourself), and most green plumage has no green pigment. Rather, the feather is constructed of layers; one layer reflects the wavelength of light that gives the color we see, while a deeper layer absorbs the other wavelengths.
In some cases, feather colors result from a combination of structural colors and pigment. Yellow pigments overlaying the blue-reflecting structural characteristic of the feathers produce the greens on some ducks.