Nature Done Wright

   This guy could be the least popular bird around, because of its parasitic behavior, but you have to give it credit for being wily. Because it leaves its eggs in other birds'  nests, the Brown-headed Cowbird can lay a lot more eggs each breeding season — at other birds' expense.

    The Cornell Ornithology Web site has a neat photo of a Brown-headed Catbird egg in a warbler nest here.