Every spring I get reports from astonished readers describing a small bird feeding a much larger, obviously begging chick. Can you explain this, readers ask. The answer is “brood parasitism.” ...

First, the host loses an egg when the cowbird makes a deposit because the female will physically remove it. Second, the cowbird chick is so much larger than the host species that it crowds out the ...

Unlike the majority of birds, brown-headed cowbirds (Molothrus ater) do not start life surrounded by their own kind. The females do not build nests, but instead add their eggs to the clutches of other ...

Black birds with a greenish sheen and brown heads sometimes visit my yard during spring migration. These are male brown-headed cowbirds, and they often arrive in mixed flocks of red-winged blackbirds ...

Today’s comment of the day comes directly from a bird’s worst nightmare. In response to today’s post on the nesting habits of brood parasite, the cuckoo finch, commenter Aloicious shares this even ...

During the late spring and early summer months when birds are nesting and watching over their eggs, you're apt to spot an unwelcome avian visitor in your backyard or neighborhood. Often lurking just ...

Brown-headed cowbirds (Molothrus ater) deposit their eggs into the nests of other birds, which then raise the cowbird chick. Female cowbirds thus have limited options for impacting their offspring’s ...