... Cowbird, Cow Pen Bird, Dwarf Cowbird, Eastern Cowbird, Nevada Cowbird. The brown-headed cowbird is probably best known for its parasitic egg-laying behavior.
Males are black birds with dull brown heads.

The brown-headed cowbird is thought to have a center of origin in the Great Plains of North America, but has expanded in both directions to spread across most of North America. (Figure 1). "Brown-headed cowbird (Molothrus ater)" (On-line). Adult males are shiny black, while first-year males are duller black. Worse, egg removal can result in retribution by cowbird parents. A brown-headed cowbird chick in a southwestern willow flycatcher nest. Brown-headed Cowbirds generally avoid forests. The song of the brown-headed has the highest frequency range of any species in North America. Although over 200 different types of birds are known to have nests parasitized by the brown-headed cowbird, some birds, such as the common tern, a few species of sandpipers, killdeer, ruby-throated hummingbird and red-headed woodpecker, fail as foster parents. Two dead Development and fragmentation of forests in the eastern United States have allowed Brown-headed Cowbirds to greatly expand their range eastward.

Home Range.

Once she has found a suitable host, the cowbird … In winter, Brown-headed Cowbirds roost along with several species of blackbirds in flocks numbering more than 100,000 birds.

Title Brown-Headed Cowbird Range - CWHR B528 [ds1668] Publication date 2016-02-0100:00:00 Presentation formats digital map FGDC geospatial presentation format vector digital data Other citation details These are the same layers as appear in the CWHR System software.

Females are much smaller and solid brown with a whitish throat and light streaking on their undersides. Only two species of cowbirds, Brown-headed and Bronzed, are found in North America.Both cowbird species are generalist parasites, laying their eggs in the nests of a wide range of other species. English: Brown-headed Cowbird

A 2007 study, led by avian ecologist Jeffrey Hoover with the Illinois Natural History Survey, was the first to document what’s known as “mafia behavior.”In the experiment, scientists observed the effects of removing Brown-headed Cowbird eggs from parasitized warbler nests.

Brown-headed cowbirds have large home ranges because they may travel between nesting and feeding sites each day.

Their home range size depends on their specific habitat. The Basics The Brown-headed Cowbird (Molothrus ater) is a brood parasite, meaning that it lays its eggs in nests of other species. The Brown-headed Cowbird is native to much of Canada, the United States, Mexico, and and the Bahamas. A female cowbird quietly searches for female birds of other species that are actively laying eggs. The Brown-headed Cowbird is well known--and widely disliked--for its practice of laying eggs in the nests of other species.

The behavior of the brown-headed cowbird causes range expansion at the expense …

The Birds of North America Online.

This bird has a range reaching up to 11 million square kilometers, and the estimated population of this species is very large and believed to be around 56 million individual birds.
Brown Headed Cowbird Song - Download CD - Excellent - Download CD Molothrus Ater Fullaire. ... Lowther, P. 2003.

Furthermore, each female cowbird is capable of laying dozens of eggs each breeding season (Scott and Ankney 1980, Lowther 1993), and the potential for adverse effects to host species can be significant. Brown-headed Cowbird: Breeds throughout much of Canada from southern portions of Yukon and the Northwest Territories south throughout the U.S. Spends winters in central and southern parts of breeding range from the Pacific Coast, the southwest, the Ohio River … Figure 1.