" But what is the real color of leaves? As a child I was once told that our blood is really blue, like the blue veins of our wrists; we only think blood is red because it turns color during a chemical reaction with the air. At the time I wondered how to test if this were true; I could think of no way to examine blood without exposing it to air. Unless blood is exposed to air, I thought then, we can't see it at all.
Perhaps this is what happens to the birds here: perhaps it is the act of joining the air that calls forth their colors; perhaps the rest of the time the birds are really all green, and the leaves, though disguised by chlorophyll, are really the color of plumage. "

― Sy Montgomery , Spell of the Tiger: The Man-Eaters of Sundarbans