Welcome to Gaia! ::

The bird you pointed out is a budgerigar, shortened to 'budgie'.

They are able to be visually sexed. Some color mutations cannot, but the yellow one you pointed at is called a lutino and can. Just look at the cere (the 'nose' above the beak that contains the nostrils). Males will have purple ceres, females have ceres ranging from brown to tan (sometimes even white).

If your budgie hasn't reached sexual maturity yet (at around a year old), you can't visually sex them. You may be able to tell if it's male or female by its singing/vocalizations in general- males sing and are very vocal, females generally not so much- but that's it.

Curious, what do you mean 'caught'? Budgies are only native to Australia, and they're illegal to catch wild there (not to mention do not come in colors like lutino). Is yours an escaped pet or something?

We have a female that'll chitter along when her brothers are singing, but she doesn't full out sing with them. Their mom chirps every once in a while, but never during their singing.

Your green one looks to be male, and the yellow one looks to be female. Just from a glance.


Here were 4 of mine with variations of cere color... link
The blue one on the left is a typical male, with a rich blue cere (nose).
The white one is a dark eyed clear female, who has a cere like your lutino would.. except her cere was mostly white with a small amount of tan.
The yellow/green one is a typical female, with a light blue/white cere, but IRL it's currently a nutty brown, so it does vary. It looks similar to your lutino's cere.
The white/blue one on the right is a pied male, who has a purpleish cere.

Females generally vary from whiteish blue to brown.. while males go with a bright blue or purple.