Unless it's a farm, no more than two.
UNLESS IT'S A FARM!
Obtw, I'm not going to get "Swine" flu, it's a goddamn bird. Also, we have come to conclusion that Franky is an adult, as goldfinches are relatively small, and she also has a barely visible broken wing.
We are going to take care of her for a while until we can get her to a vetranarian or humane society center.