This is a bit more recent history than what is mentioned in this thread but today while listening to the Meerkat keeper talk, the keeper mentioned the reason that the zoo stopped keeping free roaming Indian Peafowl and that is that one of the Peafowl got inside one of the Meerkat enclosures and met its demise from the Meerkats.
Zoos Victoria are very much down on what they call "unnecessary deaths". In fact, they have a committee at corporate level that looks at all deaths not caused by natural causes. Another example is that at Werribee they only keep free-range male guinea fowl, as when they kept females as well, hatchlings were predated on by ravens and other birds, and these were deemed unnecessary deaths.
The most notorious example of this as far as ZooChatters are concerned would be Eastern bongo. One ran into a fence and so Zoos Victoria decided they’d never be held at Melbourne Zoo again (at least not in that exhibit).