What size is a "large" bird?

I go into petco every once in a while to buy fish food because the fish store i like to use has terrible hours. I try to avoid the parrot section whenever I go into petco because I hate to see the parrots kept in such bad conditions. But most of the time I can’t help myself and I go peek at the birds. I feel so bad for these two little black capped conures they are kept in these small little cages side by side. They have a seed diet, their feathers look in terrible condition and to boot they have been for sale for at least six months, which probably means they have been in a cage for at least six months. I feel so guilty for leaving them there but I know if I buy them they will just be replaced with two more little victims. They are always clinging to the side of the cage as close as they can be to one another. I feel so sorry for their situation Other parrots that I have seen sold there are sun conures, but they usually get sold pretty quickly as far as I can tell, green cheek conures, and of course budgies. The last time I went in there I saw what I think was a blue capped pionus (I can’t be sure). It was defiantly at least the size of one though. He was in the same size cage they were keeping the green cheeks in . I know petco is not by law allowed to sell larges birds. I’m wondering what constitutes a large bird? Anyway sorry about my rambling on. I just can’t beleive how poorly people can treat animals it’s sad.

Large birds would be macaws,palm cockatoos and other black cockatoos and a medium would be African greys,amazons , white cockatoos and anything smaller would be considered small.The conures feathers might look in bad condition because they could be very young at young ages they usually start with messy feathers and look like they’re hanging out all over the place