Bronzed Cowbird Life History


Habitat TownsOpen fields, pastures, scrubby areas, tropical semideciduous forest, tropical deciduous forest, tropical scrub, lawns, golf courses, and agricultural areas.Back to top


Food InsectsSeeds and arthropods.Back to top


Nest Placement

Nest Tree

Nest Description

None. Lays eggs in nests of other bird species.

Nesting Facts
Egg Description:Unmarked bluish green.
Condition at Hatching:Helpless with sparse gray down.
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Behavior Ground ForagerForages as it walks on ground; rarely in vegetation, frequently in association with cattle; forages in flocks, often with other blackbirds.Back to top


Conservation Low ConcernPopulations of bronzed Cowbird are stable, but may have declined slightly between 1966 and 2014, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 9 million with 10% breeding in the U.S., and 73% spending part of the year in Mexico. They rate a 6 out of 20 on the Continental Concern Score and are not on the 2014 State of the Birds Watch List. Settlement of North America by Europeans has undoubtedly permitted expansion by Bronzed Cowbird into areas converted into agricultural habitats. Management concerns are more likely for host species than for the cowbird. Bronzed Cowbird parasitism has been assumed to be a factor (along with habitat loss) responsible for decreasing populations of Altamira Orioles and Audubon's Orioles in southern Texas.Back to top


Ellison, Kevin and Peter E. Lowther. 2009. Bronzed Cowbird (Molothrus aeneus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2015.2. Patuxent Wildlife Research Center, Bird Banding Laboratory 2015.

North American Bird Conservation Initiative. 2014. The State of the Birds 2014 Report. US Department of Interior, Washington, DC, USA.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Sauer, J. R., J. E. Hines, J. E. Fallon, K. L. Pardieck, Jr. Ziolkowski, D. J. and W. A. Link. The North American Breeding Bird Survey, results and analysis 1966-2013 (Version 1.30.15). USGS Patuxtent Wildlife Research Center 2014b. Available from

Sibley, D. A. (2014). The Sibley guide to birds, second edition. Alfred A. Knopf, New York, USA.

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