You laugh, but those guys can get violent... I remember when I moved in to my current house, there's a gum tree outside in my backyard, with a family of koalas. The amount of times I got woken up by their shrieking was unreal. Those guys are like banshees when they're going at it. It's basically mating and brawling at the same time.
I don't hear much of them anymore, but that's not surprising - one of them appears to have disappeared.