Cowbirds are members of the blackbird family with an unsavory reputation. This species is a nest parasite—female cowbirds never build nests of their own, instead laying their eggs in the nests of other species. Despite the species’ odious habits, the satin sheen and bubbling song of a male brown-headed cowbird in the springtime can be a pleasant addition to your backyard community.
The male brown-headed cowbird is shiny black all over, save for his head, which is (as might be expected) chocolate brown. The female is drab gray-brown all over, with faint or no streaking. She can be recognized by her stout build, strong, pointed bill, and slightly notched tail.
Brown-headed cowbirds lay their eggs in the nests of other birds, such as finches and warblers. These “host” birds may eject the cowbird egg, abandon the nest, or raise it as their own. A baby cowbird often grows more quickly than its nestmates, crowding them out of the nest and eventually dwarfing its adoptive parent.
Any small songbird seen feeding a much larger fledgling has become host to a cowbird. Adult cowbirds usually forage by walking along the ground, picking at seeds and insects. The song of the male, which is often given repeatedly as the male pursues a female from ground, to tree, and onward, is a short, bubbly glub-GLEE!
Brown-headed cowbirds are widespread and stable or increasing as breeding birds in Massachusetts. They often form flocks and feed in agricultural areas during fall and winter, but winter counts of this species have dropped significantly in Massachusetts over the past few decades. Learn more in our Breeding Bird Atlas 2