The only grackle I have ever seen with white feathers around the collar.
Well-known local birders Angel and Mariel commented as follows:
Great photo Tom, thanks for sharing. Leucistic birds always seem to generate lots of atte
ntion 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 de
fects in pigment cell differentiation during development, basically the pigmentation cell
s in a bird fail to develop properly. Leucism is often mistaken for albinism which result
s in the reduction of melanin production only, whereas leucism can cause a reduction in a
ll 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 r
ed or pink eyes, bills, feet, and pink fleshy areas due to the lack melanin production wh
ereas leucism only affects the feather coloration. The eyes are not really red/pink but a
ppear to be due to the lack of melanin production in both the retinal and iris which allo
ws the underlying blood vessels to show through causing the appearance of red or pink eye
s. 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.