Interesting pic and good points Julian.
Deserved more response. Afraid I can’t be much help ...
From: Julian Robinson
[
Sent: Wednesday, 12 March 2008 1:46 PM
To: canberrabirds chatline
Subject: [canberrabirds] Pallid Kooka
One of the interesting sights on the excellent COG outing to
the Goobragandra River (near Tumut) on the long weekend was a ghostly
Kookaburra.
It looked paler to my eye than shown here, probably I've over-processed it in
trying to confirm whether or not it had any blue in the wing, which it doesn't.
I was trying to determine if it was leucistic or albino but that seems to be a
tricky subject. It could be albino if the brown which is evident is not
due to melanin since albinism is purely a lack of melanin. But the brown
probably IS melanin. And then again one would imagine it would still have it's
blue colouration in the wing which is, I believe, usually/always(?) a
structural colour caused by interference patterns in the microscopic structure
of the plumage, and not pigment-related. Which makes it stranger still,
since this bird would then be missing both pigment and structural colour.
Leucism is supposed to related to pigment aberration too, not structural
colouration, so the loss of blue is still unexplained if it is leucistic.
Maybe kookaburra-blue is a pigment since it is not shiny and is rather more
subtle than most bird-blues.
The eye colour is no clue since I had to 'fix' the eye to remove flash effect
as it was dusk when photographed.
It was certainly a strange and ghostly sight in the early evening light.
(Another group saw it in daylight).
Julian
