Hanging Around Downunder

I walked by the lake today and, drawn by the noise, I came to a tree in which there was a whole flock of Corellas.  What caught my eye about 30feet up were these two, hanging under a branch.  They looked like they were locking beaks (fighting?kissing??who knows) and then I noticed that only one was hanging onto the branch above. They take some sorting out, looking at the shots so I have added a couple of extras.  Finally they must have agreed to let go, because they fluttered upwards and off in a swirl of feathers. I have never seen this behaviour before so did a bit of research, but came up with nothing. So, make of it what you will.
Thanks freezabird, for correcting my identification of these birds. A small matter of no sulphur crest!;o)