Brown-Headed Cowbird

Male Brown-Headed Cowbird

The adult male cowbird is shiny black in color with a brown head. The adult female is slightly smaller and is dull grey with a pale throat and very fine streaking on the underbelly meaning they are sexually dimorphic. Brown-headed Cowbirds live in grasslands with short trees as well as woodland edges, brush thickets, and residential areas. Insects such as grasshoppers and beetles make up about a quarter of a cowbird’s diet. Female cowbirds have a large calcium requirement from laying so many eggs. To satisfy it, they eat snail shells and sometimes eggs taken from nests they’ve visited. Brown-headed Cowbirds do not build their own nest. Experiments done with artificial nests suggest that Brown-headed Cowbirds tend to choose nests containing eggs of smaller volume than their own. They get their name from their close association with cows which flush up insects for the birds to eat. When males sing, they often raise their back and chest feathers, lift their wings and spread their tail feathers, and then bow forward. The males might also do this to impress females for mating. Female Brown-headed Cowbirds find nests by watching for signs of other birds building nests, or they flutter through vegetation trying to scare birds from their nests. Their process of using others bird's nest for there own eggs have endangered some bird species across America.