While some birders are exceptionally good at identifying birds by listening to their calls and songs, the rest of use rely upon seeing a bird’s color to identify what it is. And beyond just the color, we need to see the pattern of color on a bird’s feathers to be sure we’ve got it right.
Even then, it’s not always easy to be certain.
How do bird feathers get their color?
Birds, along with fish and insects, are the most colorful of nature’s creatures. Which colors we see depends upon a number of factors that can be grouped into two general categories:
- colors produced by the structure of a bird’s feathers
- colors produced by chemical pigments
Structural colors are produced by the scattering of reflected light orchestrated by the formation of a bird’s feather. Chemical colors, on the other hand, rely on a range of pigments.
Additionally, birds are tetrachromatic, which means they can see ultra-violet light. Because we don’t perceive UV light, birds see colors we don’t. This means that some birds have colors even more complex than what we observe.
Pigments are chemicals that absorb and reflect different wavelengths of visible light. As far as pigments in birds are concerned, there are three groups of pigments called carotenoids, melanins, and porphyrins.
The feather colors attributed to carotenoids have nothing to do with the structure of a bird’s feathers. Instead, carotenoid colors in birds are the result of their eating foods that contain carotenoids.
Once ingested, the carotenoids are deposited into a bird’s feathers and will absorb and reflect different wavelengths of visible light. For example, flamingos are pink because of this process.
Flamingos get their pink feathers by eating brine shrimp, which have eaten red and yellow carotenoids. These carotenoids reflect the red and yellow wavelengths producing what looks to us like pink feathers.
The deeper the color of the food, the stronger that color will appear in the feathers.
See also: Flower Colors that Attract Birds
Melanin is a pigment we share with birds but, unlike carotenoids, it’s produced within a bird’s cells. There are two groups of melanins—one ranges in color from grey to black, while the other ranges from buff to brown.
In addition to providing color to a bird’s wings, melanin also helps to strengthen them. It’s why so many birds have darkly colored wing tips and edges. These parts of the wing are most exposed to the wear and tear of flying and to parasites. Melanin helps to keep these critical feathers strong and is essential to a bird’s survival.
Finally, melanins can combine with carotenoids. For example, yellow carotenoids can mix with dark brown melanin to produce an olive green color found in some forest birds.
The cool thing about the family of porphyrins is that they produce vibrant colors and, when found in bird feathers, they fluoresce bright red under UV light. They’re also the rarest pigments among birds and account for the brown in owls and the vivid reds and greens in turacos.
It may be surprising to learn that blue jays and bluebirds are not blue. Instead, their color, and the blues and violets found in other birds, is the result of light scattering through extremely small pockets of air and keratin. When visible light hits these pockets, they absorb all the colors except blue, which they reflect, and we see.
See also: How to Attract Blue Jays
Some birds like grackles, European starlings, and hummingbirds have feathers that appear iridescent. The barbules on these birds’ wings reflect different wavelengths of light depending upon the angle of reflection and these angles produce the iridescence.
Why do birds have colored feathers?
Colored feathers serve two purposes:
- They assist birds in finding mates
- They help protect them from predators
It’s easy to tell a male and female cardinal apart from the deep red color of the former compared to the duller pinkish brown of the latter. However, it can be more difficult to differentiate the sexes among other birds… at least it is for us. But remember, birds can see various lights in the UV spectrum and sometimes what we can’t see help birds separate the males from the females.
Additionally, a bird’s color can signify its health and prowess.
The deep yellow feathers of a goldfinch—the result of carotenoids—indicate to a female a healthy mate likely to produce healthy young. Its black cap—the result of melanin—is an indication of how aggressive he would be and provides a strong hint about his ability to protect its territory and defend a nest.
See also: How Do Birds Mate?
Finally, some birds are colored to camouflage themselves against predators. The color and markings of whippoorwills, sparrows, woodcocks, and others can make these birds difficult to spot in their habitat. Some blend in so well, they seem invisible.
The complex interaction among pigments, feather structure, and patterned markings in birds bring delight to those of us who take the time to notice. For birds, these same features help to ensure reproduction and survival.
That’s another win-win for Mother Nature.