This is How Birds Look to Other Birds

There are birds who only appear sexually dimorphic when you look at their patterns in UV, otherwise males and females appear the same to humans.

An example of this comes from a paper known because of its title: Blue Tits Are Ultraviolet Tits

Of note, human retinas can see into the UVA part of the spectrum, but that is normally blocked by the lens. People who have operations where they get an artificial lens in their eye can then see a bit of UV. But they still have only three, or fewer, receptors (and blue is not very high resolution), so it is still difficult to see much detail.

While UV photography is interesting, birds vision is even MORE interesting than this - they see colours we can't even imagine. Where we have three base colours (red, green, blue, as seen in HTML colour) - they have four. They are tetrachromatic.
So instead of our black, red, green, yellow, blue, purple, cyan and white corners, they have 16 corner colours. We're colourblind compared to them.

https://en.wikipedia.org/wiki/Bird_vision#Light_perception