Brian - I should get in that bark-chewing is still
food-related, Galahs and other cockatoos attacking the sought-after cambium,
and ring-barking is not uncommon. (Joe Forshaw has told me this
several times and, if he is listening, would think little of my memory if I
failed to mention it.) However I still think that in its very
obvious seasonal manifestation it is related to pair behaviour, because it is
usually engaged in by paired birds, takes place most often near the present or
proposed nest-hollow, and is often accompanied by wing-flexing and
head-bobbing. I think the goanna theory is unlikely - you
would need a gun-metal finish to deter a goanna and many smooth-barked trees
like E mannifera would be more climbable after a bit of chewing than before.
Incidentally, I am told that for the current urban tree-planting
program smooth-barked trees are being preferred for fire-hazard-reduction
reasons, even the medium-barked Yellow Box being rejected for that reason.
From: Brian Fair [
Sent: Sunday, 12 July 2009 8:12 PM
To: canberrabirds
Subject: [canberrabirds] Galahs Chewing Bark
I
am just writing to add some thoughts and observations about Galahs chewing
bark. Galahs have been known to ringbark trees with their
chewing. They have been known to chew away the bark of trees that
they intend on nesting in and one theory is that they do this to stop
goannas from steeling the eggs from the nest. They will chew away the
bark below where the nest or proposed nest is located. The removal of the bark
would make the trunk smoother thereby making it harder for goannas to reach the
nests.
This
is a theory that my father was told after Galahs had ringbarked a few trees on
his property which is located just outside Tamworth. Any thoughts are welcome
and I would be interested to hear more about the trees that Galahs have been
see chewing in.
