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Cowbirds are birds belonging to the genus Molothrus in the family Icteridae. They are of New World origin. They are brood parasites, laying their eggs in the nests of other species.

Molothrus ater1.jpg
Female brown-headed cowbird
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Icteridae
Genus: Molothrus
Swainson, 1832

The genus Molothrus contains:

Image Scientific name Common Name Distribution
Screaming Cowbird (Molothrus rufoaxillaris).jpg Molothrus rufoaxillaris Screaming cowbird north east and central Argentina, south east Bolivia, central Brazil and throughout Paraguay and Uruguay
Giant Cowbird - Pantanal - Brazil H8O0545 (23593619780).jpg Molothrus oryzivorus (formerly in Scaphidura) Giant cowbird southern Mexico south to northern Argentina, and on Trinidad and Tobago
Bronzed Cowbird (Molothrus aeneus) (7223072934).jpg Molothrus aeneus Bronzed cowbird southern U.S. states of California, Arizona, New Mexico, Texas, and Louisiana south through Central America to Panama
Shiny cowbird (Molothrus bonariensis) male.JPG Molothrus bonariensis Shiny cowbird South America
Molothrus ater 2.jpg Molothrus ater Brown-headed cowbird Soutwestern Canada, United States and Mexico

The non-brood parasitic baywing was formerly placed in this genus; it is now classified as Agelaioides badius.


Cowbirds eat insects, including the large numbers that may be stirred up by cattle. In order for the birds to remain mobile and stay with the herd, they have adapted by laying their eggs in other birds' nests. The cowbird will watch for when its host lays eggs, and when the nest is left unattended, the female will come in and lay its own eggs. The female cowbird may continue to observe the nest after laying eggs. If the cowbird egg is removed, the female cowbird may destroy the host's eggs to dissuade further removals, according to the Mafia hypothesis.[1]


  1. ^ Jeffrey P. Hoover; Scott K. Robinson (13 March 2007). "Retaliatory mafia behavior by a parasitic cowbird favors host acceptance of parasitic eggs". Proceedings of the National Academy of Sciences. Retrieved 26 August 2009.

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