Brown-headed cowbird nestlings are also sometimes expelled from the nest. Song sparrows' nests are parasitized by the brown-headed cowbird. The brown-headed cowbird may parasitize this species. An individual shiny cowbird may lay its eggs across many different nests. Wilson's warbler is a frequent host for the brown-headed cowbird. The female cowbird may continue to observe the nest after laying eggs. The eastern phoebe is occasionally host to the nest-parasitic brown-headed cowbird ("Molothrus ater"). One study found that 9% of nests had brown-headed cowbird eggs in them. Physical appearance of the shiny cowbird adult depends on subspecies. These include the coyote, the white-tailed deer and the brown headed cowbird. Brown-headed cowbird females can lay 36 eggs in a season. Before European settlement, the brown-headed cowbird followed bison herds across the prairies. Habitat and cowbird management costs $1 million per year as of 2003. It is also known commonly as the short billed cowbird. This species is also commonly parasitized by the Brown Headed Cowbird and the Bronzed Cowbird.