At 18:25 26/10/98 +1100, Susan Myers wrote:
>
> I believe that leucism and albinism are not the same things. An albino lacks
>all pigements while a leucistic animal has a reduced intensity of
>pigmentation. If Jo's cockatoo had dirty looking plumage & orange tail
>feathers I would guess it was a leucistic bird rather than an albino. An
>albino bird would surely be pure white all over with red eyes...?
I'm not an expert here either but this seems right to me. Albinos
genetically lack ability to express or produce any pigment at all, where as
leucistic individuals try to express pigments but the chemical pathways
don't deliver. True albinos are exceptionally rare where as leucism is
relatively common. By definition there is no such thing as "partial
albinism."
Museums actually contain lots of leucistic birds. Some species (like male
blackbirds) or groups are more prone than others. Rails show a great
tendancy for leucism. I have seen lecistic specimens of about 10 species.
In the Coral Sea, Buff-banded rails are quite common. At N.E Herald Cay one
in four rails are leucistic (off white with faint buff bars on the
scapulars and wing coverts, pink bill and red eye. It would seem that one
of the founding individuals of the colony on this island was leucistic and
in the absensce of predators the genes have survived and spread.
This is possibly similar to the extinct White Galinule (Porphyrio albus) of
Lord Howe Is. It was a large swamphen with some all white individuals ,
some blue, and some piebald.
There is one or possibly two leucistic brush turkey(s) at Pallarenda in
Townsville, present for at least 3 years. All white plumage but black bill
and dark eyes.
The most unusual case I've encountered is probably museum specimens of
schizocroic Keas where the green is replaced with white so the birds are
yellow and white like giant domestic budgies.
There are also lots of notes on leucistic birds (often miss-identified as
albinos) in journals such as Corella, Emu and ABW.
Cheers,
David James
PO BOX 5225
Townsville Mail Centre 4810
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