Humans are color blind compared to birds!

[Pajarita]

This is an article about a study done on hummingbirds but can be applied to parrots, too. The study was to find out if birds can see UV non-spectral colors - non-spectral colors are the ones that are a blend of colors that are in opposite wave lengths - like violet that has red, a shortwave, mixed with blue, a longwave so a UV non-spectral would be a color mixed with UV light. And they can!

https://www.smithsonianmag.com/smart-ne ... Y0Mjg1NwS2