The Brown-headed cowbird (Molothrus ater) is a common bird of Oregon’s open country and as such is found throughout Malheur National Wildlife Refuge. The species gets its name from a long association with large grazing animals. Historically, cowbirds followed American bison across the Great Plains, feeding on insects flushed by the animals’ movement as well as seeds from grasses and weeds. Today, they often forage near cattle and horses, where grasshoppers, beetles, and other invertebrates become easier to find. In Oregon, brown-headed cowbirds are common migrants and breeders in open habitats, including agricultural areas, sagebrush and juniper steppe, riparian zones, and woodland edges—habitats represented across the broader Malheur landscape.
At first glance, a male brown-headed cowbird can look almost entirely black. Look again: its body has a glossy, dark sheen while its head is a warm chocolate brown. Females are more subtly colored, being plain gray-brown overall, with a short tail and a thick, conical bill that can appear almost finch-like. Both sexes are stocky birds, usually seen foraging on the ground in fields, along roadsides, near livestock, or in mixed flocks with other blackbirds.
Brown-headed cowbirds are North America’s most widespread brood parasites. Rather than building a nest, a female lays her egg in the nest of another bird species. The host bird then incubates the cowbird egg and feeds the young cowbird after it hatches. A female may lay more than three dozen eggs in a summer, placing them in nests of many different species.
In spring and summer, listen for the male’s distinctive bubbling, gurgling song. It is often described as a low “glug, glug” followed by higher, sliding whistles. Males may puff their feathers, spread their tails, and bow forward during displays. You might look for brown-headed cowbirds in open fields, meadows, pastures, brushy thickets, and in mixed flocks of blackbirds, especially during migration and winter.
