Sorry for the poor picture quality---I did the best I could with what I was sent. Local listserv here in Maryland, Baltimore area (I believe). Post-er says the bird has been hanging out around her suet feeder for months.
I'm baffled. If I saw this near the road during the winter somewhere rural, I'd call it a Snow Bunting, but that's just plain wrong, isn't it? This is a (sub)urban setting, near feeders, apparently since early fall.
Leucistic mockingbird...? Escaped exotic? At a loss here.