Why do some birds (like conurs) have white around their eyes while others (cockatiels, budgies) do not?

Its the iris Cockatiels you can see in the light and budgies you can see clearly Afult budgies have it and babies have black eyes.

The iris is actually the colored part of the eye. Like the brown, green and blue. White fleshed birds have eye colors too. The white is just some flesh around the eye, but I'm not sure why some birds have it and others don't.

I'm not sure but I think it has to do with were the birds were originated from. Cockatiels and Budgies are from Australia while conures are from South America.

It similar to parrot tail feathers: some are long and some are short. It has to do with the different species. I don't think there is any reason to the white skin around the eyes. It doesn't serve any purpose like wings or feet do. It's basically like the color of the feathers from a bird. Actually, even the feather coloring has a purpose. A sun conures feather coloring is dull as a baby to protect it from preditors. If a baby sun conure had adult plumage as a baby, I think they would be extinct because they are very attractive to the natural preditors in the wild.

I know the iris is the coloured part of the eye I thought she was talking about the iris I didnt know she meant the flesh around the eye as I call Cartoon eyes.

Nope, she meant the white ring.

I have a question about this. All of the lovebird species (peachface, fichers, masked etc.) all come from all over Africa and places neighboring it, like in Madagascar, and they're all lovebirds, but some like masks and fichers have the white eyes like my Teak did, but others, like the peachface, abyssinian and grey headed don't. So why's that?

Yeah I know the white ring white flesh same thing.

I can see calling it "cartoon eyes."

When you ask about a white ring you need to specify whether you're talking about the iris or bare skin around the eye lol. Because some parrots have one and some have the other, and some have neither. I don't know of any who have both but there might be one somewhere.

The answer for why either one is there is that basically there was some advantage to it for that species so they evolved that way. Maybe a bare ring around the eye meant there were fewer eye problems from feathers getting into the eye due to some aspect of the way that species lived. Maybe the opposite sex thought it was attractive.

The color of the iris is caused by pigments in the eye. There are a lot of bird species that have pigments in the eye that they don't have in their feathers. Pigments do more than just provide coloring, some of them have a protective function or may enhance vision. White or silver coloring in the eyes or skin is often caused by a type of pigment called purines. As far as I know nobody has actually studied the eyes of parrots to find out what kind of pigments they contain, but purines are a prime suspect for species with a whitish iris.