Brown Headed Cowbird

Identification and Pictures

(Molothrus ater)

Brown-headed cowbirds are stocky, glossy black birds with brown heads, 6 to 8 inches.  They have a short tail, long pointed wings, and a thick head with a short conical bill like fiches.  The females are brownish gray.  The females may be mistaken for Rusty blackbird females but the cowbird's bill is much smaller.  Juveniles are paler than females, and have soft breast streaks.  Young birds are often seen being fed by smaller birds of another species.

Photos by Keith Lee.  The camera I use is the Canon EOS 40D.

Brown-Headed Cowbird Sound

The male's song is a bubbly sound like glug-glug-glee given while he leans forward in his dance.  While he sings the female will give a series of liquid chatters.  They have a flight call that sounds like pee-see-see.  Sound

Preferred Habitat

Brown-headed cowbirds can be found year-round in the western U.S., and much of eastern U.S.  Their summer range extends up into Canada.  They like riversides, wood edges, fields, pastures, and suburbs.  In winter, Brown-headed cowbirds may join large flocks with several blackbird species. 

Breeding and Nesting

Males gather in small flocks to do courtship displays where they sing with their wings, and tail spread while fluffing their feathers to attract females.  The females will usually pick the dominant male from the group.  

The Mafia Bird

Cowbirds are brood parasites.  They do not build nests, and they do not take care of their young.  They lay their eggs in the nests of other birds.  Their eggs are white, light blue, or green with red, brown, or purple speckles.  Amazingly their strategy is very successful, and the other birds often raise the young cowbird as one of their own.  It is believed cowbirds lay their eggs in the nests of as many of 220 bird species.  Female cowbirds may lay as many as 40 eggs in a season.  The female will watch the activities of other birds to find one building a nest.  They prefer birds that are smaller than themselves.  When a nest is discovered she will return to lay her egg.  She will remove one of the host's eggs from the nest in around 60 to 70 percent of the time.  Cowbird's eggs hatch sooner and grow faster than many other birds giving the young cowbirds the advantage of more food.  They will often pitch the host bird's eggs, and young out of the nest.  Catbirds are better than other birds at detecting and removing the unwanted egg.  Yellow Warblers will often build a new nest over the top of the cowbird egg.  Cowbirds have been labeled Mafia Birds because recent studies have shown that if a host bird removes the cowbird egg they routinely come back and destroy the nest and eggs in it.  It is thought that this behavior results in the host birds learning they are better off leaving the unwanted egg.  Watch the PBS video Cowbird mafia.

Food 

Cowbirds eat seeds, grains, and insects.  They often forage on the ground.  They got their name from the habit of foraging for insects in herds of grazing animals.  They will often eat eggs removed from a nest they have laid an egg in.  They also eat snails, giving them the much needed calcium they need to lay large numbers of eggs. 

To learn about other favorite birds click here.