Brown-headed Cowbird

 

A male brown-headed cowbird. It's famous for something it does not do... build nests. Female cowbirds lay eggs in the nests of other birds -- over 200 have been documented. Those other birds end up raising cowbird chicks with their own broods. I've seen small birds feeding chicks larger than themselves -- cowbirds.  

Brown-headed cowbirds are historically associated with buffalo herds. Traveling herds kick up insects and flatten tall grass revealing seeds, and both help the birds find a meal. These days cows and horses are more likely than buffalo, but the birds don't really need them. I saw this one in the New Jersey Pine Barrens, far from grassy fields of grazing mammals. Click to enlarge.