Leucistic Great Blue Heron

[Donkees]

4. Birds: ''Leucism refers to an abnormality in the deposition of pigment in feathers.''

Leucism refers to an abnormality in the deposition of pigment in feathers. There is some disagreement as to whether the condition is genetic or caused by pigment cells that were damaged during development. Whatever the cause, the condition can result in a reduction in all types of pigment, causing pale or muted colors on the entire bird. Or the condition can cause irregular patches of white, and birds with these white patches are sometimes described as “pied” or “piebald.”

https://feederwatch.org/color_variant/albinism-and-leucism/

Leucistic Dark-eyed Junco, by Gary Mueller, Rolla, Missouri