Don't be confused. Think laterally. The enclosure was undoubtedly already there before it was used for Emu. It just happened to be handy....No-one would build a roofed enclosure for flightless birds.
plainly these emus can fly, or they would not be in an exhibit entitled "Hunters of the Sky". I believe in Australia emus are avoided during the breeding season because they dive-bomb intruders who come too close to the nest.
