Unlike birds whose plumage is mostly blue, the green coloring of a green bird’s feathers is primarily a combination of pigment and structure, not just a trick of the light. These birds’ emerald green, ...

"Not only does having a fourth color cone type extend the range of bird-visible colors into the UV, it potentially allows birds to perceive combination colors like ultraviolet+green and ...

A combination of chemical and genetic analyses of the parrots revealed that ALDH3A2 is more active in yellow and green feathers than in red ones, suggesting that the enzyme helps feathers color swap.

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 Princeton-led research team trained wild ...