Ah ok. But then I think it is a waste of space to not fill up the moat and have the fence cover that area up too. So the animals would have more space and the visitors would not have such a bad viewing position.
There is a viewing window located to the right on the photo which offers visitors a better look.As far as filling the moat it comes down to money which is the same reason the old bear grottoes have not been demolished.
