Feather Color in Birds

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Anyone who knows me, or has read my articles knows that I am passionate about wild birds; and not just because of their colors. There are many birds that lack bright and powerful hues and tints. It is the way nature has designed and used those colors to enhance birds’ survival that evokes my appreciation.

Pigment and the way a feather is constructed determine the color of birds’ feathers. The pigments come from just 3 different groups.

Melanins which produce black, brown, rust and pale yellow
Carotenoids that absorb blue light and turn it into red, orange and bright yellow
Porphyrins which make pink, brown, green and rusty red

Humans, animals and plants all have melanin present in different amounts and for different reasons:

In people, melanin determines the color of our skin, the iris of our eyes and the color of our hair. In some plants, like fungi, it appears to protect the plant from the radiation produced by sunlight.

But melanin in birds occurs as tiny granules of color in the feathers as well as their skin. It serves to strengthen and protect the feathers from everyday wear and tear. If there is no pigmentation in the feathers, i.e. they are all white, there is very little strength. That is why most white birds have some black on their feathers, especially flight feathers that get the most use. Black feathers contain the most melanin and therefore maintain the most strength.

Carotenoids in humans act as antioxidants. Orange-colored fresh fruits and vegetables contain the most carotenoids. When supplemented with avocado or avocado oil, they are readily absorbed and used to the utmost benefit in the human body to protect it against the harmful effects of free radicals.

When carotenoids are manufactured by plants, they protect the plant from ultraviolet light or sun damage; plus they aid in the process of photosynthesis.
Birds that eat plants, or things that have eaten plants, that contain carotenoids will be red, orange or yellow. Combinations of melanin and carotenoids produce olive greens. Northern Cardinals, Purple Finches and Goldfinches are all examples of birds that metabolize carotenoids.

Studies have shown that female Northern Cardinals choose their mates based on depth of color: the darker the male, the better the carotenoid source; therefore, the stronger his genes and his food-finding abilities. Her offspring will be the best of the best, with the greatest chance of survival and the ability to find the best food sources, just like their papa.

Flamingos are pink because of the blue green algae and shrimp in their diet. As their liver breaks down the carotenoids, the molecules are sent to the skin, legs, beak and feathers of the bird.

The third pigment is porphyrin, which comes from the modification of amino acids. One of the best-known substances created by the chemical processing of porphyrins is hemoglobin. If you were to shine an ultraviolet light on the feather of a ring-necked pheasant, it would produce a brilliant red fluorescent color. That’s the porphyrins at work; and they can be found in the chlorophyll of dark green plants, and the red blood cells in humans, animals and birds.

It is believed that porphyrins help regulate temperature, as they are found in the downy feathers on the brood patch in owls in particular. They are also present in birds’ eggs that are left unattended as a rule for longer periods of time by the parents as they hunt. Presumably the porphyrins function to not only camouflage the eggs, but to help keep them warm until Mom and Pop reappear.

Besides pigmentation, feather construction also determines color. For instance, if you have ever seen the changing throat patch of a hummingbird, then you have witnessed structural color at work. Those particular feathers refract light because of their structure at the microscopic level. They are in effect ‘unzipped’; their barbs are not woven tightly together, so they split light into the various colors we see, depending upon the angle at which we view them.

This prism effect is what gives certain birds their iridescent appearance. However, iridescent feathers are the weakest of all because of their ‘loosely woven’ structure. That’s why no bird has fully iridescent flight feathers. This iridescence shows up only where feathers are not stressed by flight.

Birds such as indigo buntings and blue jays appear blue because of their feather structure. Unique cellular layers overlying the feathers reflect the light, which we then see as blue. In reality, the pigment in the feather makes it brown. You can prove this if you find a blue feather and shine a light on it from behind.

Nature has given birds their unique colorations for different reasons: strength, protection from ultraviolet light and environmental stresses, camouflage, and the ability to entice the best mates to insure survival of the species. No matter what their color, or lack thereof, birds continue to be my source of inspiration and creativity, as well as a strong connection to the way nature works.