The Snow Bunting is black and white in breeding plumage. To accomplish this transition, however, they don’t get a new set of feathers. The brown color is just a fringe on the edge of each black or white feather. That is best seen on the wing feathers near the middle of this bird’s back. The brown fringe wears off during the winter. That leaves the back and the rest of the wings completely black except for the white wing patch. The brown also wears off the head, rump, and underside leaving them all white. The bill changes to all black for the breeding season.
From Nov, 27, 2016 - Snow Buntings