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Help develop a Bird ID tool!

Brown-headed Cowbird

Molothrus ater ORDER: PASSERIFORMES FAMILY: ICTERIDAE

IUCN Conservation Status: Least Concern

The Brown-headed Cowbird is a stocky blackbird with a fascinating approach to raising its young. Females forgo building nests and instead put all their energy into producing eggs, sometimes more than three dozen a summer. These they lay in the nests of other birds, abandoning their young to foster parents, usually at the expense of at least some of the host’s own chicks. Once confined to the open grasslands of middle North America, cowbirds have surged in numbers and range as humans built towns and cleared woods.

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Keys to identification Help

Blackbirds
Blackbirds
Typical Voice
  • Size & Shape

    Brown-headed Cowbirds are smallish blackbirds, with a shorter tail and thicker head than most other blackbirds. The bill has a distinctive shape: it’s much shorter and thicker-based than other blackbirds', almost finch-like at first glance. In flight, look for the shorter tail.

  • Color Pattern

    Male Brown-headed Cowbirds have glossy black plumage and a rich brown head that often looks black in poor lighting or at distance. Female Brown-headed Cowbirds are plain brown birds, lightest on the head and underparts, with fine streaking on the belly and a dark eye.

  • Behavior

    Brown-headed Cowbirds feed on the ground in mixed-species groups of blackbirds and starlings. Males gather on lawns to strut and display for mates. Females prowl woodlands and edges in search of nests. Brown-headed Cowbirds are noisy, making a multitude of clicks, whistles and chatter-like calls in addition to a flowing, gurgling song.

  • Habitat

    You’ll find Brown-headed Cowbirds in many open habitats, such as fields, pastures, meadows, forest edges, and lawns. When not displaying or feeding on the ground, they often perch high on prominent tree branches.

Range Map Help

Brown-headed Cowbird Range Map
View dynamic map of eBird sightings

Field MarksHelp

  • Adult male

    Brown-headed Cowbird

    Adult male
    • Short to medium length rounded tail
    • Thick, triangular bill
    • Brown head
    • © ashockenberry, Ontario, Canada, September 2008
  • Adult female

    Brown-headed Cowbird

    Adult female
    • Large, stocky songbird
    • Relatively short tail
    • Stout, conical bill
    • Solid gray-brown overall
    • © Jay Paredes, Boynton Beach, Florida, May 2010
  • Parasitized Yellow Warbler nest

    Brown-headed Cowbird

    Parasitized Yellow Warbler nest
  • Juvenile

    Brown-headed Cowbird

    Juvenile
    • Stocky, heavy-bodied songbird
    • Stout, conical bill
    • Streaked breast
    • Plain gray-brown overall
    • © flipkeat, Missisauga, Ontario, Canada, June 2011
  • Juvenile with Common Yellowthroat parent

    Brown-headed Cowbird

    Juvenile with Common Yellowthroat parent
    • Large and stocky songbird
    • Thick, conical bill
    • Pale gray-brown with some streaking on breast
    • Juveniles often seen being fed by parents of smaller species
    • © Darin Ziegler, Colorado Springs, Colorado, July 2009
  • Adult male

    Brown-headed Cowbird

    Adult male
    • Brown head contrasting with glossy blackish body
    • Short, thick, pointed bill
    • © robinsegg, Wyoming, June 2006
  • Adult female

    Brown-headed Cowbird

    Adult female
    • Dull brown overall
    • Slim body with large head and thick bill
    • Dark eye
    • © tsiya, April 2008
  • Adult male

    Brown-headed Cowbird

    Adult male
    • Blackish body with greenish iridescence
    • Brown head
    • © maia bird, December 2008

Similar Species

  • Adult male

    Bronzed Cowbird

    Adult male
    • Adult male similar to adult male Brown-headed Cowbird
    • Body and head glossy black
    • Wings with blue-purple sheen
    • Red eye
    • © Tripp Davenport , Uvalde, Texas
  • Adult female

    Red-winged Blackbird

    Adult female
    • Similar to female Brown-headed Cowbird
    • Heavily streaked below
    • Contrasting dark cap and eyeline
    • Thinner, more pointed bill than Brown-headed Cowbird.
    • © Judy Howle
  • Adult male

    Red-winged Blackbird

    Adult male
    • Similar to adult male Brown-headed Cowbird
    • Red and yellow wing patch
    • Longer and thinner bill than Brown-headed Cowbird
    • © Ted Schroeder
  • Male and female

    Brewer's Blackbird

    Male and female
    • Male Brewer's Blackbirds are glossy blue-black on the head and have a bright-yellow eye
    • Both sexes have longer, more slender bill than cowbirds
    • Both sexes have longer tails and longer legs than cowbirds
    • © Eric Rosenberg, San Jose, California, June 2007

Similar Species

Cowbirds are smaller and shorter-tailed than other members of the blackbird family, with a shorter, thicker bill. The brown head of male Brown-headed Cowbirds can be difficult to see in poor light, so body shape and bill shape are the best clues. Female cowbirds are much less streaky than female Red-winged Blackbirds. Common Grackles are larger, longer-tailed, and lankier than Brown-headed Cowbirds. Male grackles and Brewer's Blackbirds show more iridescent colors in full light. Bronzed Cowbird and the rare Shiny Cowbirds of southern states are quite similar, but lack the male's brown hood and have longer bills.

Backyard Tips

Even though Brown-headed Cowbirds are native to North America, many people consider them a nuisance bird, since they destroy the eggs and young of smaller songbirds and have been implicated in the decline of several endangered species, including Kirtland's Warbler and Black-capped Vireo. Cowbirds often flock with other species of blackbirds, and they may come to your yard if it contains open ground or lawn, or if you scatter grain for ground birds. If your yard is large enough to keep livestock, there's a good chance you will find cowbirds there.

Find This Bird

Look for Brown-headed Cowbirds in fields, meadows, and lawns. During winter and migration, search through mixed-species blackbird flocks and look for the glossy black plumage and subtle brown head in males and the short, stout bill and unmarked brown of females. Learn the male’s gurgling song and the female’s chatter call, and you’ll hear them often.

Get Involved

Brown-headed Cowbirds are a focal bird species for the Celebrate Urban Birds! project. Conduct a 10-minute count and record whether or not you see cowbirds.

Visit NestWatch to learn how to observe and report activity at bird nests

You Might Also Like

Cowbirds and Conservation (Audubon)

Brown-headed Cowbirds in Grasslands (USGS)

Brown-headed Cowbird: A bird that never nests has a huge impact on nesting birds.

Brown-headed Cowbirds: from buffalo birds to modern scourge (Smithsonian Migratory Bird Center)

All About Birds blog, Identify the Brown, Streaky, Juvenile Songbirds of Summer With These Tips, July 23, 2014.