eBird describes the Brown-headed Cowbird this way: Stout bill. Short tail and stocky body. Males are glossy black with chocolate brown head. Females are gray-brown overall, without bold streaks, but slightly paler throat. Juveniles streaked brown. Found in open woods, farmland, and stockyards. Forages by walking on the ground. Often in flocks with other blackbirds in winter. Visits feeders. Unpopular due to their parasitic habit of laying eggs in nests of other birds.
I saw, and photographed a male/female pair of Brown-headed Cowbirds at the Old Barn in Warbler Woods on May 8, 2020.
“Cool Facts” About the Brown-headed Cowbird From All About Birds…
- The Brown-headed Cowbird is North America’s most common “brood parasite.” A female cowbird makes no nest of her own, but instead lays her eggs in the nests of other bird species, who then raise the young cowbirds.
- Social relationships are difficult to figure out in birds that do not build nests, but male and female Brown-headed Cowbirds are not monogamous. Genetic analyses show that males and females have several different mates within a single season.
- Brown-headed Cowbird lay eggs in the nests of more than 220 species of birds. Recent genetic analyses have shown that most individual females specialize on one particular host species.
- Some birds, such as the Yellow Warbler, can recognize cowbird eggs but are too small to get the eggs out of their nests. Instead, they build a new nest over the top of the old one and hope cowbirds don’t come back. Some larger species puncture or grab cowbird eggs and throw them out of the nest. But the majority of hosts don’t recognize cowbird eggs at all.
- Cowbird eggs hatch faster than other species eggs, giving cowbird nestlings a head start in getting food from the parents. Young cowbirds also develop at a faster pace than their nest mates, and they sometimes toss out eggs and young nestlings or smother them in the bottom of the nest.
- In winter, Brown-headed Cowbirds may join huge roosts with several blackbird species. One such mixed roost in Kentucky contained more than five million birds.
- The oldest recorded Brown-headed Cowbird was a male, and at least 16 years 11 months old when it was recaptured and rereleased during banding operations in Wisconsin.