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Brown-headed Cowbird - BirdForum Opus

(Redirected from Molothrus ater)
Adult male
Photo © by Joseph Morlan
Pacifica, California, USA, 31 March 2020
Molothrus ater


Photo © by OhioMoose
Central Ohio, 30 May 2007

Male: 7.5-8.7 in (19-22 cm); female: 6.3-7.9 in (16-20 cm)

  • Finch-like bill

Male – glossy black plumage (sometimes a blue-green sheen can be seen), rich brown head, dark eye
Female – brown plumage, paler on the head and underparts, dark bill and eye
Juvenile – similar in color to female, but with streaking on breast and paler bill

Similar Species

Female Shiny Cowbird is similar to female, but has a longer, more pointed bill. Female Brewer's Blackbird is much larger with longer bill and darker body.


Populations in the Far West average smaller than those elsewhere.


Juvenile (left) with Dark-eyed Junco foster parent
Photo © by Joseph Morlan
Pacifica, California, USA, 18 June 2015

Canada, USA and Mexico
Canada: Alberta, British Columbia, Manitoba, New Brunswick, Newfoundland, Labrador, Nova Scotia, Northwest Territories, Ontario, Prince Edward Island, Quebec
USA: New England, Alaska, Alabama, Arkansas, Arizona, California, Colorado, Connecticut, District of Columbia, Delaware, Florida, Georgia, Iowa, Idaho, Illinois, Indiana, Kansas, Kentucky, Louisiana, Massachusetts, Maryland, Maine, Michigan, Minnesota, Missouri, Mississippi, Montana, North Carolina, North Dakota, Nebraska, New Hampshire, New Jersey, New Mexico, Nevada, New York, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Vermont, Washington, Wisconsin, West Virginia, Wyoming
Mexico: Baja California, Tamaulipas, Oaxaca, Los Coronados Islands



Female, nominate subspecies
Photo © by Stanley Jones
Union Bend Road, Mumford, Robertson County, Texas, USA, 16 October 2022
Photo © by Marysan
Imperial County, California, 14 November 2004

This is a polytypic species which consists of four subspecies[1]:

  • M. a. artemisiae:
  • M. a. obscurus:
  • M. a. ater:
  • Central and east-central US; migrates to Gulf Coast, Florida and southern Mexico
  • M. a. californicus:


Farmland, foreste edges, suburbs.



Cowbirds are brood parasites; the female removes one egg from the host nest and lays one of her own. Four to five white, brown speckled eggs are laid, one at a time.


Song: A liquid, bubbly gurgle followed by an upslurred, high-pitched whistle (given during display).
Call: check or a rattle.


  1. Clements, J. F., T. S. Schulenberg, M. J. Iliff, T. A. Fredericks, J. A. Gerbracht, D. Lepage, S. M. Billerman, B. L. Sullivan, and C. L. Wood. 2022. The eBird/Clements checklist of Birds of the World: v2022. Downloaded from https://www.birds.cornell.edu/clementschecklist/download/
  2. Lepage D. (2020) Brown-headed_Cowbird in Avibase - The World Bird Database. Retrieved 4 April 2020
  3. Lowther, P. E. (2020). Brown-headed Cowbird (Molothrus ater), version 1.0. In Birds of the World (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.bnhcow.01
  4. Fraga, R. & Garcia, E.F.J. (2020). Brown-headed Cowbird (Molothrus ater). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/62295 on 5 April 2020).
  5. Jaramillo, A. & Burke, P. (1999) New World Blackbirds: The Icterids. Princeton Univ. Press, Princeton, New Jersey. ISBN 0-69100-680-6
  6. Wolf, L. (1987) Host-Parasite Interactions of Brown-headed Cowbirds and Dark-eyed Juncos in Virginia. Wilson Bulletin 99:338-350. PDF

Recommended Citation

External Links

GSearch checked for 2020 platform.1