I'm not exactly a fan of this nest/brood parasite. Whyfore? Well, cowbirds have this bad habit of laying their eggs in the nests of smaller native songbirds, and their demanding offspring will be brooded, raised and fed by their 'foster' parents, often at the peril of the other much smaller and less assertive babies. Anyhoo, Brown-headed Cowbirds do occasionally show up at our feeders, so that's why they're accorded this post.
5/2/07 Brown-Headed Cowbird (Molothrus ater) on the bird feeder in the back orchard.