This site has interesting info:
Budgerigar
Color Vision - Human beings have trichromatic vision, which means that our eyes have three cone cell types. We are unable to see colors in the UV spectrum. Budgies, on the other hand, have tetrachromatic vision, which means that their eyes have four cone cell types. They are able to see colors in the UV spectrum, and they take full advantage of it when mating and foraging.
Amazing....can all birds see in this spectrum?
Budgerigar
Color Vision - Human beings have trichromatic vision, which means that our eyes have three cone cell types. We are unable to see colors in the UV spectrum. Budgies, on the other hand, have tetrachromatic vision, which means that their eyes have four cone cell types. They are able to see colors in the UV spectrum, and they take full advantage of it when mating and foraging.
Amazing....can all birds see in this spectrum?