tbob

Help needed in ID these 2 birds filmed in Taiwan, sorry for poor quality but it is just a computer screen capture

Bob

HKBWS Vicky

The 2nd one looks like Brown Shrike to me. How come the color is so pale?
The 1st one is a wagtail? Yellow wagtail but with some kind of albino??

EricB

This is a very rare xanthochromic Yellow Wagtail.It is usually a genetic abnormality (like albinism) but occasionally can be dietary.I'm not sure why most of its flight feathers are white  but there appears to be some darker feathers in there.  It seems a little bit odd if its missing the gene to make melanin ( the dark pigment lost in albinism) why it's eye appears so dark.Either way it's clearly  xanthochromic , possibly with a second genetic pigmentary problem.
The shrike is washed out looking because it is leucistic.
Here are a couple of links explaining things
http://en.wikipedia.org/wiki/Xanthochromism
http://en.wikipedia.org/wiki/Leucism
I'd be interested if these birds were found in a cluster( same vague area) - as this would suggest some thing triggering DNA mutation (-like a mild poison or radiation in the environment) affecting the population.As an isolated phenomena leucism is not uncommon but xanthochromism is extremely rare in wild birds.
eRic

[ Last edited by RUWright at 27/01/2011 06:18 ]

tbob

Thank you both for the detailed replies, I will check with the person that filmed the birds as to whether it was in the same location

Bob


PS: The birds were filmed within 3 Km of each other

[ Last edited by tbob at 27/01/2011 20:35 ]