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Posted by Angel & Mariel on 12:38:12 05/13/09
In Reply to: Common Grackle with white collar posted by Tom Friedel
Great photo Tom, thanks for sharing. Leucistic birds always seem to generate lots of attention due to their different in appearance.
The Common Grackle in your photo shows a condition known as Leucism; which is also known as pied or piebald some also refer to leucistic birds as dilute . Leucism results from defects in pigment cell differentiation during development, basically the pigmentation cells in a bird fail to develop properly. Leucism is often mistaken for albinism which results in the reduction of melanin production only, whereas leucism can cause a reduction in all types of pigment.
Leucism usually affects portions of the bird where albinism always affects the whole bird. Leucistic birds may also be affected over the whole bird but true albinos always have red or pink eyes, bills, feet, and pink fleshy areas due to the lack melanin production whereas leucism only affects the feather coloration. The eyes are not really red/pink but appear to be due to the lack of melanin production in both the retinal and iris which allows the underlying blood vessels to show through causing the appearance of red or pink eyes. In contrast, leucistic birds have normally colored eyes, bill, and feet.
One interesting note about leucism is that the ratio of white to normal-colored feathers can vary considerably not only between generations, but between different offspring from the same parents.
Thanks for sharing your photo.
Nature is Awesome
Angel & Mariel
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