Hare Krishna,
I personally don't like the idea of keeping animals in cages. I think they should be able to roam around naturally. Especially birds, yes, it may be more work for them (look for food, danger of predators), but that is their nature. In some situations animals are being kept captive to save the species, maybe in a zoo or a sactuary. This is a whole different situation, anyway this is just my personal opinion...