do you mean in walk-through aviaries? I've never ever seen free-roaming crowned pigeons. In many places that would just be a death sentence from predators.
I don't know. Although a couple of days after I visited in March two Bongos went on display. Some mechanism must exist to allow for the importation of animals. Going in the other direction, the Honolulu Zoo recently exported to the mainland United States and France (and elsewhere I'm sure) Lions and Sumatran Tigers born at the zoo.
