The wide variety of nonspectral colors available to birds is the result of their ancient four color-cone visual system. "Tetrachromacy -- having four color cone types -- evolved in early vertebrates," ...

image: While humans have three color cones in the retina sensitive to red, green and blue light, birds have a fourth color cone that can detect ultraviolet light. A research team led by Princeton's ...

While humans have three color cones in the retina sensitive to red, green and blue light, birds have a fourth color cone that can detect ultraviolet light. A research team led by Princeton's Mary ...

To find food, dazzle mates, escape predators and navigate diverse terrain, birds rely on their excellent color vision. “Humans are color-blind compared to birds and many other animals,” said Mary ...

Plumage. An incredible world, for an incredible phenomenon. Say it with me now: plumage. Picture the colors, their variety and richness. Picture, while you’re at it, some other stuff relevant to this ...