Leucism

Leucism happens when a mutation occurs that prevents melanin from being deposited in feathers or hair. Albinism is a condition in which there is a complete lack of melanin in the body. Melanin is responsible for dark colorations such as black/brown and red/brown variations.

These images show comparisons of animal species with leucistic pigmentation versus normal pigmentation.

The top left image shows a pale gray or leucistic skunk while its litter mate shows the usual black pigmentation. The two lower left-hand photos show a pale, leucistic female mallard and a typically pigmented duck. The two lower right-hand images show first, the winter plumage we see in an American goldfinch compared to a goldfinch with a white ring (pied) around the birds head.