Three Gang-gang Cockatoos, a male and two females, were in a tree where there was successful breeding last season. The male was chasing off some Sulphur-crested Cockatoos that may have been interested in the hollow used by the Gang-gangs last breeding season. The male chased the Sulphur-crested Cockatoos to a tree about 20m to the west. One of the females joined him there, then they followed the Sulphur-crested Cockatoos that flew off much further to the west. The other female Gang-gang stayed in the original tree the whole time. The other Gang-gangs may have returned to the initial tree as I heard more Gang-gang calls from that tree later in the morning when I was further away.