Brown-headed cowbird

Molothrus ater 2

Brown headed cowbird female in JBWR (25487)

File:LS110137 BHCO B Brown-headed cowbird one call.ogg

cowbirdsincourtship

Molothrus ater -San Luis Obispo, California, USA -juvenile-8

Brood parasitism cowbird yellowthroat

Brown-headed Cowbird

The Brown-headed Cowbird (Molothrus ater) is a small passerine bird belonging to the family Icteridae. It is native to North America and is known for its brood parasitism, where it lays its eggs in the nests of other bird species.

Description

The Brown-headed Cowbird is sexually dimorphic. The adult male has a distinctive brown head, contrasting with its glossy black body. The female is duller in color, with a gray-brown plumage that provides camouflage while laying eggs in host nests. Both sexes have a short, conical bill suited for their diet.

Habitat and Distribution

Brown-headed Cowbirds are found across a wide range of habitats, including grasslands, woodlands, and agricultural areas. They are highly adaptable and can thrive in both rural and urban environments. Their range extends from southern Canada through the United States and into northern Mexico.

Behavior

Feeding

Brown-headed Cowbirds primarily feed on seeds and insects. They often forage on the ground, sometimes following grazing animals to catch insects stirred up by their movement.

Brood Parasitism

One of the most notable behaviors of the Brown-headed Cowbird is its practice of brood parasitism. The female cowbird lays her eggs in the nests of other bird species, leaving the host birds to incubate and raise the cowbird chicks. This can negatively impact the host species, as cowbird chicks often outcompete the host's own young for food and parental care.

Reproduction

Female Brown-headed Cowbirds can lay a large number of eggs in a single breeding season, often targeting multiple host nests. The eggs typically hatch faster than those of the host species, giving cowbird chicks a competitive advantage.

Conservation Status

The Brown-headed Cowbird is currently listed as a species of Least Concern by the International Union for Conservation of Nature (IUCN). However, their brood parasitism has raised concerns about the impact on certain host species, some of which are threatened or endangered.

Related Pages

• Passerine
• Icteridae
• Brood parasitism
• Grasslands
• Woodlands