I think we have been here before, but as I understand it:
males take 7 years to attain black plumage; females have a black
bill; sub-adult males – 1st, grey/brown bill; 2nd/3rd
virtually indistinguishable from Fs; from then on, when they are likely to be
carrying sticks [remember? - ‘five, six, pick up sticks’],
palish or pale bill.
From: David Rosalky [
Sent: Monday, 31 August 2009 8:39 PM
To: Bird List
Subject: [canberrabirds] Black cockies and bowerbirds
As
I was leaving home this morning for work, I was delighted to confront three
Yellow-tailed Black Cockatoos demolishing an Albizia tree in my front
yard. The tree has been damaged badly by YTBCs before. They
seem to find larvae in knots where small branches have formerly broken
off. Their activities have sometimes caused a whole branch to be severed.
Also
Satin Bowerbirds. Last week I noticed a blue SBB flying near the Italian
Embassy in Grey St Deakin. The Embassy is only about 300m from my place
as the SBB flies. I will have to search for a bower in the vicinity.
Over the weekend, I saw three (and possibly four) green birds in my back yard
and the adjacent yard. One was making that amazing growling or churring
noise, and another was seemingly foraging for short sticks on the ground and
attempting to break off thin sticks from a tree. The bird on the ground
also briefly put on a display, lowering its body, spreading its wing and
shaking them. These actions all suggest to me a group of immature
male pretenders to the mature bird's throne, rather than females interested in
the old boy himself. I confess that I still can not distinguish immature
males from females despite much gazing at the field guides.
