find out more

Photo © Al Tuttle

What are brood parasites and what do they have to do with Cowbirds?

This is when Brown-headed Cowbirds lay their eggs in the nests of other birds who then incubate their eggs and raise the cowbirds as their own. Brown-headed Cowbird females can lay 36 eggs in a season. Over 140 different species of birds are known to have raised young cowbirds. Host parents may sometimes notice the cowbird egg. Different species react in different ways. Gray Catbirds destroy the egg by pecking it. Some species may simply build a new layer over the bottom of the original nest. Brown-headed cowbird nestlings are sometimes expelled from the nest.

Return to FAQ list

Cornell Lab of Ornithology

Cornell Lab of Ornithology