They produce a range of colors, including red, brown, pink, and green. Birds that have this pigment tend to be owls, turacos, pigeons, and grouse.

Photo: A macro shot of a red-and-green macaw’s (Ara chloropterus) eye, Serra da Capivara National Park, Piauí state, Brazil. (Leonardo Ramos, Public domain, via Wikimedia Commons) ...

Red-tails prefer open areas, such as fields or deserts, with high perching places nearby from which they can watch for prey. But these birds are adaptable and also dwell in mountains and tropical ...

In addition to blue, green and red cone cells, many birds have cone cells that are sensitive to ultraviolet light, allowing them to see a broader spectrum of colors than people can. “Their ...