Hmm, didn't see the photo. I agree it seems that the bird can be accurately
described as leucistic. I guess I figured an absence of black pigment would
leave the bird white rather than yellow. Ah well.
Regards,
Chris
On 11/23/06, <>
wrote:
Hi Chris,
On the site you provided a link for, it has an example of a YTBC that is
prodominantly yellow.
The description is "Bird is washed out in patches alternating with dark =
partial leucistic/lutino"
However, what you say about it being hyperxanthic is an interesting point
too.
The following questions are raised in my mind:
1.\ If a yellow YTBC is classed as being Luecistic, would this mean that
a YTBC is 'capable' of being yellow all over, but the black pigment is
usually strong enough to overpower the yellow colouration.
2.\ If a yellow YTBC is classed as hyperxanthic, would this mean that the
yellow pigment is so strong that its overpowering the black pigment? Or
potentially the bird is partially luecistic in its black pigmentation, and
partially hyperxanthic in its yellow pigment...or combination there of???
The following is from the article:
*Feathers (and scales in snakes for instance) can have multiple
concentrations of multiple pigments. When one of these pigments, say black
for ease of understanding, is missing, the color appears washed out -- that
is, it is left without the darkness created by the black pigment, in
addition to say, red and yellow (those are the three common pigments in
nature). This is the generally accepted use of leucism -- some pigment
missing, but some pigments left.*
So what I can deduce from this (to answer my own questions) is that
possibly a YTBC has no red pigments, only yellow and black. So a yellow YTBC
is probably Luecistic, meaning the black pigment is missing, and the yellow
pigment remains all over the body.
Peter
*"Chris Sanderson" <>*
Sent by:
23/11/2006 05:24 PM
To
"Mike Jarman" <> cc
Subject
Re: [Birding-Aus] (NOT) Melanistic Yellow-tailed Black-cockatoo
Hi Mike,
I believe the correct term for too much yellow pigment is hyperxanthic
(based on a non-exhaustive google search on the topic of feather pigment
anomolies). Your bird is possibly a combination of leucistic (lacking
dark
pigments) and hyperxanthic (overabundance of yellow) creating the strange
combination in your bird.
This website has seemingly good descriptions (though I'm no
aviculturalist)
and links to pictures at the bottom to illustrate examples.
http://www.pkblogs.com/milkriver/2005/03/env-albinism.html
Regards,
Chris
On 11/23/06, Mike Jarman <> wrote:
>
>
> Philip Veerman pointed out to me that the term melanistic is not correct
> for this bird as melanistic means an excess of black pigment. Maybe the
> term is leucistic, I dont really know. But whatever the terminology
is, it
> sounds like a spectacular bird.
>
>
> Greg,
> I have seen a pair of osprey hanging around Lake Conjola (NSW south
coast)
> for the last few months. What time of year do they normally breed?
Lake
> Conjola has many large trees around the shores and in the tributaries
that
> could possibly host a breeding pair.
>
>
> cheers
>
> mike
>
>
>
> ---- Greg <> wrote:
> > Hi Mike,
> >
> > A few years ago there was an adult female Glossy Black-Cockatoo
feeding
> > young in a large hollow in a Scribbly Gum south of Grafton, North
Coast
> NSW.
> > She was completely yellow apart from some greyinh edging to the
feathers
> and
> > an orange tail panel. Quite a sight!
> >
> >
> > Regards
> >
> > Greg Clancy
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