Leucistic White-throated Sparrow in Toronto

We heard White-throated Sparrows singing in the garden and looked out to see this striking partially leucistic White-throated Sparrow in Toronto on 28 April 2016. To find out how to name this plumage, I consulted articles by aberrant plumage expert Hein van Grouw. He describes leucism as "the partial or total lack of both melanins in the feathers (and skin)." This is an inherited condition in which the pigment cells are absent from some or all the areas of skin where the feathers grow. "It varies from a few white feathers (partially leucistic) to the plumage being completely white." The bill and legs are the normal colour. This White-throated Sparrow has normally coloured eyes, which is typical of all leucistic birds. All albino birds, however, have red eyes, so it's not an albino. Reference: van Grouw, H. 2013. What colour is that bird? The causes and recognition of common colour aberrations in birds. British Birds 106:17-29. PDF available on line:



Here's another view of this interesting sparrow. Toronto on 28 April 2016.

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