around the UQ lakes

["Bob Moffatt" <>]

Craig,
There is an increasing population in northern NSW based in the Tweed and 
extending south. My thoughts are that the Qld birds may be more 
resiliant/robust (not in stature) and expel potential predators better than 
those birds which have succumbed to predation in the past in NSW (??). I was 
surprised just how agressive the display of a pair of nesting birds became 
when I approached to within 15m (they bluffed me!).  Thus the northern birds 
are (expanding their population and) extending their range southward. Maybe 
Qld birds are subtly different to the southern population (?) and have 
developed behavioural characteristics that allow them to persist better than 
a former population (?).
Would be intersted to read other folks thoughts on this interesting 
phenomenon.
Bob