It’s interesting Melbourne still had Bison as late as 2004! Their enclosure was replaced by the current Water Recycling Plant which opened circa 2010. They presumably left not long after 2004.
I also remember the Lorikeet Aviary opposite the elephant exhibit - it held the peacocks for a while too but was unfortunately later demolished
@Jambo
This was my first vist to Melbourne, so I remember it like this well - I had never been to a major zoo before, and was amazed at all the different species! I think you're right, the Bison don't seem to have been around much longer after this.