I would go with Beeb's suggestion as the Little Corellas usually have more red in them (Blood Stained Corella being another name)
I'm not that good with the Birds
My guess is that it is young and the top beak has not grown to full length yet?
I want to stand as close to the edge as I can without going over. Out on the edge you see all the kinds of things you can't see from the center.