Description
 Part of the blackbird family, the Brown-headed Cowbird is a little smaller than other birds in its family. The male Brown-headed Cowbird has a glossy black body and a brown head while the female is plain brown. Once confined to open grasslands, the Cowbird's range has grown as people settled North America. The Brown-headed Cowbird is a brood parasite, meaning that it lays eggs in other bird's nests instead of building a nest of its own.
Range
The Brown-headed Cowbird spends the summer in western Canada, throughout the western, northern and northeastern United States. It is found as far east as Newfoundland. It travels through the United States during migration, arriving in Mexico, southern Florida and the Bahamas to spend the winter.
Habitat
 Adapted to grasslands, the Brown-headed Cowbird can live in a variety of modern habitats. It can be found in grasslands with low trees, woodland edges, brushy thickets, prairies, fields, pastures, orchards and residential neighborhoods. In the winter, the Brown-headed cowbird roosts in large numbers with other species of blackbirds. |
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Diet
 The Brown-headed Cowbird feeds on seeds from grasses and weeds. It also eats grasshoppers, beetles and other insects that live in grasslands. To get enough calcium to produce its many eggs, the female eats snail shells and eggs shells from the nests it invades.
Life Cycle
 The Brown-headed Cowbird uses a different strategy than most to raise its young. The female doesn't build a nest but rather lays her eggs in a nest belonging to another species. Studies have shown that Cowbirds tend to choose a nest with smaller eggs than their own. Cowbirds have been observed to lay eggs in nests of 220 different host species! The Yellow Warbler, Red-winged Blackbird and Red-eyed Vireo are common hosts.
Since the female doesn't build a nest of her own, she spends all of her energy laying eggs. Sometimes three dozen eggs are laid a season! Cowbird eggs hatch faster than other species eggs, giving Cowbird chicks a head start in getting food from the host parents. The chicks develop faster than other species and sometimes throw the other eggs out of the nest or smother the other chicks.
Behavior
 Some species, like the Yellow Warbler, can recognize Cowbird eggs but are too small to throw them out of the nest. Instead, it will build a new nest on top of the old one to stop the Cowbird from returning. |
Least Concern
