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I went to have another look at the active bower in
Hughes on the edge of the Federal Golf Course.
As I arrived, a group of four green bowerbirds flew
in. Having concluded on the weekend that the male was "shepherding" a
female to his bower, I extended my romantic imagery and assumed that there was
going to be an orgy.
But the behaviour was rather strange. As the
green birds approached the bower, the male chased them away. At one point,
three of the green birds popped out of the cover of low bushes onto open
grass. They chattered between themselves with lots of low noises and
each picked up a leaf and went back into the bushes. I don't know what
this behaviour was except possibly mimicking the mature bird in picking up items
for the bower (even though they were not blue).
Some good views revealed that one bird had dirty
patches on it. On its breast were four dark dots (a few millimetres in
diameter) and under one wing was a much larger dark patch. I assume it was
an immature male with some blue/black appearing.
So it appears that the birds were all males coming
in numbers to dispossess the mature male of his bower.
Another interesting observation was the "satin"
bird's plumage. Its general appearance is of a very inky blue/black.
But when the bird was partially obscured, the colour along the edge of the
object obscuring it (usually a branch) glowed a violety blue. It is a
striking and rather eerie effect. I assume it is some kind of
diffraction of the blue light which is formed through interference from the
feather structure.
David
Rosalky
Deakin
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