David - I assume you are referring to the bower
in Downes Place? I believe this usually has a lot of yellow Sulphur
Crested Cockatoo crest feathers at one end - I've seen or heard about this
from other local bowers. SBB often use light yellow leaves as well for
decorations.
It is likely that the green birds, or at least
some of them, were young males. These don't acquire their adult plumage
until about 7 years. The easiest way to tell them (4+ years) is by their
very light bills, about the same colour as the mature male, compared with the
darker bills of females and younger birds. I agree they were likely
trying to take bower material or destroy the bower. They are known to
learn to build bowers by watching other males and while they do build
practice bowers (often very rough untidy structures) this particular
bower is very likely the main one in the area. Stealing from or
destroying bowers is a regular pursuit for the SBB. Bowers can be
rebuilt very quickly.
Your observation of a male just starting to moult
into mature plumage is a very interesting one. My previous observations
have been that this happens locally during Feb/March [see CBN 29(1) p 33
(2004)], but I've heard about this also happening over the past couple of
months, something I still need to chase up. It's well worth keeping an
eye on this bower to see if it's happening over a similar time frame as
published.
Jack Holland
