Some may think, “If I see an Eastern Bluebird, I certainly see blue.” Well, yes you do… and no you don’t. It’s complicated!
My daughter, Julie, was active in Science Fair when she was in school. In ninth grade her project was “Pigment and Structural Colors in Bird Feathers”. Most birds’ feathers get their color from chemicals in the foods the birds eat. Those foods provide different birds with different kinds of pigments in their feathers. The pigments show color by absorbing some of the colors of the light spectrum and reflecting the other colors…we see the reflected colors. Northern cardinals reflect red, therefore we see red; American goldfinches reflect yellow, Baltimore orioles reflect orange and so on. The color blue is different, however. Bluebirds do not reflect blue, yet we see blue. There are truly no blue colored birds…anywhere. The blue we see is not a reflective color from a blue pigment, rather a refractive color. It’s physics and light playing tricks with our eyes. For blue birds, instead of the light reflecting off the feathers and showing the color of the pigment, the light enters into the feather and bends (refracts). This refracted (not reflected) light is what we see.
To study this, Julie gathered feathers from different kinds of dead birds we found along roadways. Certain federal laws forbid collecting birds or any parts of birds, including feathers, but my Bird Banding Permit allowed me to salvage dead birds. I already had several in our freezer. With mortar and pestle Julie ground the red feathers of a cardinal with the resulting powder being a red color. After grinding the feathers of a goldfinch, the powder was yellow. The color resulting from oriole feathers was orange. She destroyed the structure of the feathers but the pigments were still there and their respective colors did not change. This showed that these birds’ colors resulted from the pigments in their feathers. When she ground the eastern bluebird feathers into a powder, however, the powder was black. This demonstrated that the bluebird’s color comes from the feather’s structure, not its pigment: destroy the structure and the blue color disappears.
Every time I see a blue bird I’m thankful that nature has made a way for me to see the blue color that is not really there. Nature is AMAZING!
For a more detailed explanation of how birds make colorful feathers, see – https://academy.allaboutbirds.org/how-birds-make-colorful-feathers/
Answers: Left-to-right… Bluejay, Blue-winged Teal, Cinnamon Teal, Eastern Bluebird, Mountain Bluebird, Wood Duck, Steller’s Jay