How Do Birds Get Their Colors?
My two most memorable gifts were my first watch, because I have always been fascinated with the concept of time and how it surrounds and consumes us; and the industrial size box of 64 crayons! Later on Crayola bested themselves with an even larger size, which I was very fortunate to receive as a gift as well.
Colors, especially those emanating from the natural world, nurture and feed my creative soul. They determine in large part how I feel, whether it be happy on a sunny, green goddess day; or contemplative when the wind blows cold and grey.
And so it is when I see nature’s dots and splashes of color, and her tricks of light and dark contrasts. The sky, trees, leaves, flowers and fruits of this Earth are food for my senses. But most of all, she has given me colorful, lively and musical birds.
Anyone who knows me, or has read my articles knows that I am passionate about wild birds; though it isn’t only 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 their survival that evokes my appreciation. It is a well-known artistic principle that you cannot achieve depth of color, without the contrast or absence of color.
Females are generally brown, streaked or marked with low contrast colors so as to become nearly invisible to predators, thus protecting them so they can continue to produce offspring. And those offspring are protected in turn because of her colors, or lack thereof, and ability to blend in. Young fledglings often don’t carry bright colors until they have matured and mastered their gift of flight and escape.
So How Do Feathers Develop Their Colorations?
Pigment and how the 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
Nature's palette allows for mixing colors, so that some birds' colors are products of the combinations of two or more of the basic pigments.
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 serve to 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 flourescent 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.
Feather Structure Also Determines Color
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 like 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 melanin 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.
Test Your Knowledge of the Sources of Bird Colors
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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.
Sources: en.wikipedia.org; chemistry.about.com; Connie Smith (Grandma Pearl)