The season is here - the woods are starting to ring with the gobbling of wild turkeys, beautiful birds that are native to North America. And if Ben Franklin had his say, the "courageous and respectable, tho' a little vain and silly" turkey might have been in the running as the symbol of America!
Some of this vanity may come from the noticeable breeding display of the wild turkey - but much stems also from the amazing feathers and body details of the turkey. Have you ever taken the time for a "face to face" with a turkey? How about noticing the amazing iridescence they show in varying light conditions?
The face of the wild turkey is an intricate combination of details, which clearly expresses their emotional and hormonal state to all who take the time to pay attention. The head is covered with pink wattles and caruncles, with the colors being more vivid in males than in females. In breeding season, the colors reach their peak display. The male add to all of this an expressive "snood" on the forehead, which can quickly change size and color based on mood and sexual status. In an excited bird, it can become remarkably long, dangling beyond the beak and sporting a fire engine red color. In the calm or questioning bird (like the one above, wondering what the turkey was doing with a camera!) it will remain short and light pink. Within seconds, a bird can go from a relaxed and "small" to huge and colorful. In domestic birds, even a small scolding can cause the snood to change instantly. And praise or a good treat has incredible responses! Notice the large snood and bright coloration on the bird below! But also have a look at the amazing plumage, and how specialized it is......
Clearly, the plumage of the male turkey was designed to be showy when needed, right down to the unique "beard" on the breast -- which is larger in males and gets longer with age and fitness. This is a visual symbol to the ladies of who might be considered a "great catch". But what about the iridescense? We see it on a lot of birds - tree swallows, hummingbirds, ducks, crows, pigeons -- what is it for?
This picture demonstrates the wide range of colors seen - even in relatively flat light - on this still not at peak season bird along with the wirey, almost hair-like structure known as a "beard". The feathers overlap and intertwine in an almost flawless manner.
The color we see in bird feathers comes from the pigmentation of the feather, the structure of the feather, or a combination of the two. Some birds acquire pigments called carotenoids through their diet, while others like melanin are naturally occurring in the skin and feathers.
Iridescence, however, comes from structural coloration. A keratin protein in the feather acts as a prism, refracting shorter light waves to show blues, violets, purples, and greens. But birds are also able to mix the carotenoid color of the feather with iridescence, resulting in even a wider array of colors.
Because iridescence depends on the refraction of light, the intensity of color changes with the viewing angle and light. Birds can take advantage of this to visually communicate within their species, directing signals to mates or rivals using the iridescence. Hummingbirds use iridescense to defend their food territories, and flocking birds like starlings may use it to coordinate group movements - just like schools of fish do. The iridescence highlights distances and placements of other birds in the flock, helping to synchronize behaviour of the flock and prevent collisions.
And, of course, this iridescence is used in courtship displays and it may play a role in selecting a mate - which has been studied in peahens, and likely occurs in other species as well.
So why don't all birds have iridescent feathers? Well, they do come with a cost. These feathers are correlated with less water repelling ability than non-iridescent feathers. The structures that cause the increased refractive qualities increases surface area, allowing more water to stick to the feather and reducing water proofing - notice the careful "shingling" in the feathers above, which may be a mechanism to help combat this downside. This same increase in surface area make the feathers less efficient at self-cleaning, and more susceptible to bacteria - causing the bird to spend more time grooming.
Many think of turkeys simply as pests at bird feeders, or even as lunch. But they are remarkable birds with many specializations that help to give us insight into other species that might not be quite as demonstrative. But, much like human attention spans to shiny things, female turkeys are likely to have a longer attention span on a male turkey that shows bright coloration, plenty of iridescense, healthy caruncles, a large beard, and an expressive snood. And for a turkey, attention is the name of the game - both domestic, and wild. Domestic turkeys don't need the coloration of the wild turkeys, but they still know how to manipulate a situation with their snoods!
The instagram quiz of the week.......you likely know what species is trolling for a snack in this photo, but - are the feathers on the head structurally green, or iridescent? Take your guess and visit my instagram page to find out!