Here comes Thanksgiving and with Thanksgiving comes Grandma’s superb casseroles, your mother’s famous red velvet cake, and of course, turkey. The once threatened wild turkey is now plentiful throughout the United States due to extensive conservation efforts and now large populations of turkeys can be found throughout the Lowcountry. They flourish on Johns, Seabrook, James, Edisto, and Wadmalaw Islands and, if you’re lucky, can also be spotted on Kiawah Island year round. Standing at four feet in height and weighing up to twenty-five pounds, the Eastern wild turkey is the largest of all the turkey species in the United States. (For comparison’s sake, an average adult Bald Eagle weighs in at nine pounds!) And, while many of us have seen dozens of turkeys during our lifetimes as featherless baked, fried, or roasted dishes, those who have not seen the bird pre-Thanksgiving dinner are really missing an awe-inspiring site.
Turkeys are covered in 5,000 to 6,000 feathers from neck to knee in a variety of colors from brown, black, copper, orange, yellow, gold, red, bronze, green, blue, turquoise, gray, and white. Many of these colors appear in iridescent shades, glittering in the autumn sunlight, and have attracted the eye of humans from the time of Native Americans. If ever you encounter the opportunity to study a turkey’s feather, don’t miss it. These feathers, ranging from one and a half feet to mere inches in size, are incredibly beautiful and complex, displaying many patterns and shifting colors. The large primary flight and smaller secondary flight feathers are barred white and black. The primary and pre-tail feathers of a male turkey (or tom) are barred reddish brown and black and tipped with a large black band and a gleaming copper or light tan/yellow fringe. The secondary covert wing feathers are almost entirely a lustrous gold with a black tip. The wing bow and the remainder of the body feathers display a variety of jewel-like feathers whose colors will change according to the way light is being refracted within the feather’s structure. As such, you might see the most infinite black in these feathers or dull, foliage browns, and at other angles, you might see blood reds, burning oranges, sea greens, desert turquoises, and sunny yellows (and all in the SAME feather!). It’s truly dazzling!
With such a gamut of colors, it’s natural to wonder how one bird could possess the ability to out-color a rainbow. Before you can begin to delve into the systems creating color, though, it’s important to understand the feather itself. A feather is a structure made up of keratin which is the same material human fingernails and hair are composed of. As they are growing, feathers are considered “live” and experience continual blood flow. Once the feather has completed growth, however, the blood flow ceases and the feather is now considered “non-living”, like our nails. The feather is composed of four main parts, the shaft, vane, barbs, and barbules. The shaft is the hollow stem of the feather that is often used to hold ink in quills. The vane is composed of the barbs and barbules and is found on either side of the shaft (essentially the feather part of the feather.). The barbs are each individual hair-like structure growing directly out of the shaft and the barbules are even smaller hair-like structures that grow directly from the barbs. Both barbules and barbs are composed of microscopic hooklets that keep the feather together, allowing feathers to keep a bird dry and warm. Now, on to the fun stuff!
Colors in feathers can be caused by a number of factors. They can be caused by the chemical compounds produced by the bird’s body, by dietary pigments picked up through food, and by structure. The turkey’s feathers experience the colors they do because of both chemical compounds within the turkey and the structure of the feather. Dietary pigments do not play a major role in turkey feather coloration, like they do in the red feathers of a Northern Cardinal or the yellow feathers of a Pine Warbler, so we won’t explore this source of color. The most common factor causing colors in all birds is melanin. Melanin is a kind of pigment manufactured within the bird’s body that not only provides colors to feathers, but also strengthens them. It is found in both the skin and feathers of birds and causes earthy tones, like dark blacks, reddish browns, and dull yellows. Melanin is also the cause of dark skin in humans and is what allows us to develop suntans. In turkeys, melanin is the cause of the blacks in the wing feathers, the browns, blacks, and dull yellows in the tail feathers, and the deep black that is seen at certain angles in the otherwise iridescent wing bow and body feathers. Another biological factor that colors feathers in birds is porphyrins. Porphyrins are responsible for reddish browns, pinks, reds, and, in some birds, greens, and are themselves caused by the breakdown of hemoglobin in the bird’s blood. Porphyrins are commonly found in owls, pigeons, and gallinaceous birds, like turkeys. In the turkey, porphyrins are responsible for the reddish browns found in the tail feathers of a turkey and the overall reddish brown color of a female turkey (or hen).
Finally, the structure of the feather is accountable for the numerous lovely, iridescent colors in a turkey. Thinking back to the components of the feather, the interaction of melanin and keratin layers between barbules causes light to refract in ways that produce iridescent shine. Microscopic bubbles caused by laminations in layers of keratin within the barbules coat each feather. When light waves hit these bubbles, they reflect back to the eye in two ways. Some light waves hit the bubble and are reflected off the surface of the bubble while others actually enter the bubble and are reflected off the inside surface of the bubble. When these two reflected light waves leave the bubble’s inner and outer surfaces, they will either meet and leave the bubble in sync or will leave out of sync. When the light waves leave the bubble in sync, the bubble has acted as a prism and has caused the coupled light waves to refract and emit intensely pure and iridescent colors. When the light waves leave the bubble out of sync, they in effect cancel out one another, causing only the melanin produced black color or porphyrin browns to shine through. For this reason, the types of color and intensities reflected in the wing bow and body feathers of a turkey may change as you view the feather from different angles. Holding a turkey feather in your hand and rotating it against a natural light source will show you the reds, oranges, yellows, greens, blues, and turquoises of the microscopic, prism-like bubbles on the surface of the feather. Alternatively, backlighting one of these turkey feathers will display the natural chemically induced color of the feather caused by melanin and porphyrins. This means that the iridescent color you see isn’t the ACTUAL color of the feather, but instead an optical illusion created by the microscopic keratin bubbles. Tricked us again, Mother Nature!
Over this Thanksgiving holiday, we will certainly all have many things to be thankful for and the wild turkey has given us a couple more blessings to appreciate. In life, the turkey is a shimmering result of Mother Nature’s deft artistic hand and helps us appreciate not only the natural beauty of our world, but the microscopic complexities that cause them as well. In death, the turkey is a mouth-watering meal that both provides for and brings an entire family together in happiness and thanks for the many blessings we all enjoy. From everyone here on Kiawah Island, Happy Thanksgiving!
By Naturalist, Juliana Smith