@Mr Gharial Exactly! I'm sure that it must have held eagles or some kind of bird of prey in the past. It's near the Bird Show Amphitheater and so perhaps some of the 'show birds' have been placed here at times. It was bizarre to only see a single ground hornbill inside!
The avairy was built a couple of years for Steller's sea eagle. I don't know where the eagles are now but I saw a comment on Facebook when someone asked about them. The park replied that they still keep them but that they are in a different exhibit.