Distribution: Only in North America. Breeding distribution from south-eastern Alaska across to New Brunswick, and south to central Mexico. Winter range from California, central Arizona/ New Mexico to Kansas then to New England; south to southern Mexico and Florida.

Migration Status: Short distance migrant within North America.

Diet: Mostly seeds, but also insects.

Breeding and Nesting: Brood parasite. Cowbird females use other bird species as hosts -- laying their eggs in the nests of other bird species and relying on these hosts to incubate and raise their chicks. Brown-headed cowbirds have parasitized over 220 host species, ranging from Black-capped Vireo and Wood Thrush to Blue-winged Teal and Red-headed Woodpecker. While not all hosts make good foster parents -- a number of species reject cowbird eggs -- cowbird chicks have been successfully reared by over 150 host species, with songbirds comprising the majority of the hosts.

• Breeding Habitat -- Forest edges, grasslands/fields and residential areas.
• Nest Location -- Lays eggs in other species' nests.
• Nest Type -- Does not build own nest; nest type varies with host species.
• Clutch Size -- 4-5 (range from 1-7)
• Incubation -- 10 to 13 days, usually hatches before host species' eggs.
• Fledge -- 10 to 11 days.
• Number of Broods -- Varies, on average may lay 40 eggs per breeding seasons.

North American Status: Breeding Bird Survey (BBS) data show the following trends.

1966 -- 1996 Trends:

• Eastern BBS Region -- declining 2.0% per year;
• Central BBS Region -- declining of 0.7% per year;
• Western BBS Region -- declining of 0.5% per year;
• US -- declining 0.9% per year; and
• Entire BBS Survey Region -- (including Canada and parts of Mexico) declining 1.1% per year.

1980 -- 1996 Trends:

• Eastern BBS Region -- declining 1.1% per year;
• Central BBS Region -- declining 0.9% per year;
• Western BBS Region -- declining 0.2% per year;
• US -- declining 0.5% per year; and
• Entire BBS Survey Region (including Canada and parts of Mexico) declining of 0.8% per year.

Conservation and Management: See White Paper, Cowbirds and Conservation.