Brown-headed Cowbird

The Brown-headed Cowbird is a small, stocky blackbird best known for its unusual breeding strategy: it builds no nest of its own and instead lays its eggs in the nests of other songbird species, leaving the host parents to incubate and raise its young. Males are glossy black overall with a warm chocolate-brown head and a short, finch-like conical bill suited to eating seeds and grain.

Females look quite different, being a plain grayish-brown all over with faint streaking on the underparts, and can be easily overlooked among sparrows. Juveniles resemble females but show fine scaly streaking.

Key field marks

• Male: glossy black body with a contrasting brown head and a short, thick, pointed bill
• Female: plain gray-brown overall, faintly streaked below, with the same short conical bill
• Short tail and a distinctive habit of walking with the head bobbing

Similar species

• Male cowbirds can suggest a small grackle at a glance but lack a long keeled tail and are much smaller and stockier.
• Female cowbirds are often confused with female blackbirds or sparrows, but their plain, unstreaked gray-brown plumage and short conical bill help separate them.

Brown-headed Cowbirds are found across nearly all of North America, from southern Canada to Mexico, in open and edge habitats including grasslands, farmland, pastures, woodland edges, and suburban areas. Historically tied to bison herds on the Great Plains, the species expanded enormously with the clearing of forests and spread of agriculture and livestock.

Most northern populations are migratory, moving south in large mixed flocks with other blackbirds for the winter, while southern populations may be resident.

Cowbirds often forage on the ground in open areas, sometimes near livestock (a habit inherited from their historical association with bison, which stirred up insects as they grazed). They walk rather than hop, picking seeds and insects from the ground and short vegetation.

The male's song is a liquid, bubbling gurgle followed by a high whistle, often given while puffing out the body and spreading the wings and tail in display. Rather than building a nest, females seek out the active nests of other songbird species (over 200 host species have been recorded) and lay a single egg in each, sometimes removing a host egg. Cowbird eggs often hatch first and the chicks grow quickly, frequently outcompeting the host's own young for food.