Do you think that they were pinioned? The right wings appear to be intact. I don't know if it's possible to train crowned cranes to remain in a specific area or not.
@Summer Tanager That's a good question and I have no idea if the birds are pinioned. This zoo has loads of local Asian wildlife and @Toki is a regular visitor and might know about the African cranes.
The zoo has a few species of free-roaming birds, including the Trumpeter Swan, Mute Swan, and this species. They even had a free-roaming Southern Ground Hornbill in the past.
I think they are pinioned or restricted from flying a long distance in some kind of way. I've seen them in exhibits of lemurs, so they might be able to fly a short distance over water.
