The Woodchat Shrike with leucistic plumage is a really striking and
beautiful bird and must have puzzled birdwatchers a lot.
White colouring can arise spontaneously as a mutation in most
animals. I remember a considerable fuss being made at the birth of a
solid white (not grey) Thoroughbred foal in Australia several years ago,
from normal coloured parents. Blood tests proved that she was in fact
their true offspring and she was accepted for registration under the
name of 'Glacial'. Much is known about colour heredity in horses and
solid white is known to be associated with a lethal gene, causing early
death of the embryo - consequently it has never proved possible to
establish a stud of pure white horses which will last more than a few
generations.
I wonder if similar genetic factors affect leucistic birds, quite
apart from being so conspicuous to predators.
All the same, a white wader - Greenshank I think - was banded at
Broome and kept coming back for several years.
Anthea Fleming
in Melbourne
ANDREW ADCOCK wrote:
Hi all,
for those of you interested in odd looking leucistic birds, check out this
Woodchat Shrike from Bulgaria.
Note also that they refer to it incorrectly as 'partial albino', a common mistake. The correct term is, I believe, partially leucistic, albinism relates to the complete absence of pigmentation in either feathers or bare parts including eyes, all of which would be pink. I'm sure you've all seen those silly white Rabbits and Mice with pink eyes and I've even seen Pythons and tropical fish but all have probably come about by design through captive breeding.
True albinism is extremely rare in the wild due in no part to the animal or
bird involved being blindingly obvious to predators as well as suffering from
acute sensitivity to light (photophobia) and in some species, (particularly
dogs) deafness. I saw an albino man when I was in Africa and he could barely
open his eyes in daylight due to the sensitivity brought on by his condition.
http://www.fotobiota.com/page4us.php?sec=gal&t_id=2&g_id=159&maincat=1
All the best, Andy Adcock, UK
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