The North American Brown-headed Cowbird is a common brood parasite that lays its eggs in the nests of over 220 species. As brood parasites, nestlings can’t learn species-specific traits from parents. Instead, once out of the host nest, young birds use a chatter call to find and join cowbird flocks. This is when their social development begins. They learn to communicate from the adult birds around them, the usefulness of what they learn depending on the company they keep.