This 'turf war' was in the centre of a new roundabout. (We must have been running low on our quota of roundabouts!!).
Compared with the sulphur crest cockatoos, galahs (or Rose-breasted Cockatoos) are quite shy. Galahs form strong life-long bonds with their mate. If one is injured, the mate will stay by their side.
Saying someone is a 'galah' is derogatory Australian slang for someone who "hasn't got a clue". 'Flaming galah' describes someone who doesn't have a clue and gets in the way. (although that term is not really used much except for television!)
I don't know how the term originated, because galahs don't seem any sillier than other cockatoos.