I'm sure it was hard to tell which animals at this zoo were wild and which were captive. Based on the pelicans in the trees, I'm going to guess that the Marabou Storks were captive animals and the pelicans, ibis, and Painted Storks were wild birds and came and went.
@Summer Tanager Many South East Asian Zoos have free flinging colonies of birds, like Painted Storks, Milky Storks and Pelicans living on their grounds, so it is hard to tell