By Tony Gazso, Interpretive Naturalist

Birds are a highly diverse group of animals. They can be found on every continent on earth, in every habitat, and in every color. One of those colors, though, isn't the result of any sort of pigments produced by the bird's body–blue. For birds, there are three primary types of pigments. Melanin is a dark pigment that naturally occurs in the skin and feathers and is responsible for brown and black coloration. Carotenoids are pigments absorbed by foods. These pigments are responsible for red and pink coloration, like the red of a cardinal or pink of a flamingo. Lastly, there are pigments known as porphyrins. These pigments interact with amino acids to produce a variety of colors from reds to greens. None of these pigments produce blues. In fact, blue pigment in the animal kingdom is extremely rare–the only known animal to produce a true blue pigment is the obrina olivewing butterfly of South America.

Eastern bluebird

If a bird doesn't create blue pigments, then how are there blue birds? The brilliant blue of an eastern bluebird, blue jay, or indigo bunting is the result of structural coloration. Essentially, the feathers are built in such a way that when light hits them, it's scattered with only the blue wavelengths reaching our eyes, giving them the appearance of being blue. It's the same reason our sky appears to be blue. It's easy to see for yourself! Next time you find a blue jay feather, simply hold it up to a light, and you'll see the feather appears to be dark brown. By viewing the feather backlit, the light isn't scattered in the right way to reflect the blue back to your eyes. 

Blue jay

Blue can also appear in iridescent feathers, as seen in the common grackle. Here, the blue is still the result of the scattering and reflecting of light, like mentioned above, but with an added step. In these feathers, the microscopic structures refract the light, creating a prism-like effect. Different wavelengths of color are refracted at different angles; thus the color varies depending on the angle you're viewing them. This type of structural coloration works for all colors as well, such as those on the throats of many hummingbirds.

Common grackle

In the end, it really isn't easy being blue. It takes a very specific microscopic structure in your feathers viewed at just the right angle, but when nature gets it right, it certainly doesn't disappoint.

Indigo bunting