Molothrus ater
(Brown-headed Cowbird)


Order: Passeriformes
Order Description: Passerines
Family: Icteridae
Family Description: Blackbirds, Orioles, & Meadowlarks

Physical Description:
6-8" (15-20 cm). Male has coffee-brown head and metallic black body. Female is dark brown all over.

Similar Species- Bronzed Cowbird

Song:
Calls sound like they are coming from underwater: glug-glug-glee; also a single, high-pitched note and a rattle.

Distribution:
Breeds from northern British Columbia, east across portions of Canada, and south to central Mexico, southern Texas, Gulf Coast, and southern Florida. Winters from northern California, southern New Mexico, Kansas, Great Lakes region, New England, and Nova Scotia, south to southern Baja California, southern Mexico, Gulf Coast, and southern Florida.

Habitat:
Found in woodlands, forests (primarily deciduous), forest edges, city parks, suburban gardens, farms, and ranches. During migrationClick word for definition and in winter, also found in open situations, cultivated lands, fields, pastures, and scrub. In Idaho, alteration of sagebrush lands through grazing or agriculture has provided mechanism for cowbirds to parasitize shrub-steppeClick word for definition birds.

Diet:
Eats mostly insects, but will also eat grain, seeds, and some fruits.

Ecology:
Lays eggs in nests built by other species (I.e., nest parasitism). Forages on ground. Female defends a territory, male does not. gregariousClick word for definition. Forms flocksClick word for definition in fall and winter, sometimes with other species.

Reproduction:
Adult female usually removes eggs of host. Host incubatesClick word for definition cowbird eggs for 10-12 days (female cowbird probably produces 8-40 eggs/season). Young leave nest at 10-11 days, are fed by host, and become independent at 25-39 days.

Conservation:
Element Code: ABPBXB7030
Status: Protected nongame species
Global Rank: G5
State Rank: S5,NTMB
National Rank: N5

Important State References:
Rich, T.D. 1978. Cowbird parasitism of Sage and Brewer's Sparrows. Condor 80:348.


Design by Ean Harker©1999, 2000.
Written by Jason Karl, 2000.