the smaller birds use the capybaras because they are both a handy perch in the open wetlands and because as they walk they scare up insects. I would assume both reasons also apply for the caracaras (i.e. a perch and they may scare up large insects and small vertebrates).
I love the monkeys on the capybaras. I wish ours were in a mixed exhibit with some monkeys. I dont even care what kind... although the squirrel monkeys looked the most adorable on them. But even the shot with the turtles and ducks with them made the setting look more realistic. Guess we will just have to wait the very very long time before they get to renoing the Mayan temple.
I believe your right zoogoer2000 but I dont remember it ever. I think Ungulate mentioned it in an ancient thread. I really do wish they had more mixed exhibits in the Mayan Temple. It has the potential. Why couldnt we have anteaters with the capybaras? Or some kind of monkey (that might be an escape problem though given the exhibit design)? More birds or ducks? I can see avoiding turtles because they wouldnt want to risk missing one before the temp drops and they die being tropical turtles.
But like I said I dont think anything will be done until that area undergoes reconstruction. I hope that section gets the love and attention it so sorely deserves. South America has some truely amazing creatures and our zoo barely scratches the possible surface.
I've always wanted to see giant anteater in the Mayan Temple area. I'm not sure if there is enough appropriate holding space for them attached to any of the exhibits though. There is quite a bit of holding space in the building, but I'm not sure how much of it has access to an exhibit.