Brown-headed Cowbird
Molothrus ater 

by Dawit Eshete 

The Brown-headed Cowbird was formerly known as buffalo-bird, names given because of their well-known attachment to domestic and wild cattle.  Brown-headed Cowbird is known scientifically as Molothrus ater and is member of the family Icteridae Brown-headed Cowbird is classified as being the member of the phylum Chordata, the class Aves (Birds) and in the order of Passeriformes.  Brown-headed cowbirds are members of the blackbird family with short, conical bills and long pointed wings.  Males have a shining black bodies and brown heads.  Females are slightly smaller than males and are uniformly gray.  The upperwing and underwing coverts of adult males are black while those of younger birds show a brown or brown-gray wash.  The primary flight feathers of adult males are also black while those for females are more of a brown-gray.  They grow to a length of six to eight inches with a wingspread of 11 to 14 inches and weigh an average of one to 1.75 ounces.  Brown-headed Cowbirds are also known as brown-headed blackbird, brown-headed oriole, cow blackbird, cow bunting, cow-pen bird, cuckold and lazy bird.  

Brown-headed Cowbirds are brood parasites, they have completely abandoned the task of building nests, incubating eggs, and caring for hatchlings.  Instead, each female deposits as many as 40 eggs per year in nests that belong to other species.  More than 100 other species have provided host nests for cowbird eggs.  The female Cowbird has the task finding the nest of other tree-nesting species.  The female Brown-headed Cowbird typically chooses a nest with eggs smaller than her own and lays a single egg quickly at dawn once the host has also started laying eggs.  Unlike the parasitic European cuckoos, baby brown-headed cowbirds do not evict their nest-mates, although the female may remove and sometimes eat eggs from the host nest.  Instead, cowbird nestlings typically out-compete their smaller nest mates for food.   

Brown-headed Cowbirds are found from southern Alaska across to New Brunswick and south to central New Mexico.  They are a short-distance migrant within North America, and winters are spent through the southern portion of their breeding range.  They feed primarily on seeds and grains, and roam year round through open woodlands, farms, ranches and suburbs.  In winter they join mixed flocks of other birds, among which they can be recognized by their habit of holding their tails lifted high as they walk out in search of food.

Written spring 2004, as a service learning project for Dr. Gary Coté's Biology 102 class at Radford University.  Copyright Pathways for Radford.

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