Below is a leucistic Fox Sparrow, a bird with abnormal plumage. Leucism is caused by a genetic mutation that prevents the bird from developing normal plumage by restricting placement of melanin, the coloring agent. Feathers, as you see on this bird, show white where it shouldn't be, and plumage that looks bleached. A bird with completely white plumage is a leucistic bird, but not an albino. The latter lacks color on all body parts, not just feathers. The bird was photographed in mid-May.
