Possibly 100 metres away to the south from sighting 4393449, I heard and then saw a female Gang-gang Cockatoo in a tree. The tree appeared to be semi-dead. I then heard and saw the male a bit lower down. Both of these birds were calling and then another pair of Gang-gangs appeared and started calling. I was unsure if this second pair was the same ones that I had just seen or were a completely new pair. Both pairs almost appeared to he calling at each other. The pair that had initially caught my attention at this tree started to converge on a hollow. The male was first, where he chewed around it for a while. He then moved aside to allow the female to get to the hollow. Both pairs continued to call at each other and I decided to move away in case I was scaring them.