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Bronzed Cowbird

Topics: Birds of Colombia

The Bronzed Cowbird (once known as the Red-eyed Cowbird), Molothrus aeneus, is a small icterid.

It breeds from the southern U.S. states of California, Arizona, New Mexico, Texas, and Louisiana south through Central America to Panama.

The male Bronzed Cowbird is 20 cm long and weighs 68 g, with green-bronze glossed black plumage and red eyes. The female is 18.5 cm long and weighs 56 g. She is duller black above and browner below. Young birds are like the female but have grey feather fringes.

Like all cowbirds, this bird is a brood parasite: it lays its eggs in the nests of other birds. The young cowbird is fed by the host parents at the expense of their own young. Hosts include Prevost's Ground-Sparrow and Yellow-throated Brush-Finch.


Database entry includes justification for why this species is of least concern

Stiles and Skutch, A guide to the birds of Costa Rica ISBN 0-8014-9600-4

Further reading


Lowther, P. E. 1995. Bronzed Cowbird (Molothrus aeneus). In The Birds of North America, No. 144 . The Academy of Natural Sciences, Philadelphia, and The American Ornithologists Union, Washington, D.C.


Bowers RKJ & Dunning JBJ. (1984). Nest Parasitism by Cowbirds on Buff-Breasted Flycatchers Empidonax-Fulvifrons with Comments on Nest-Site Selection. Wilson Bulletin. vol 96, no 4. p. 718-719.

Brush T & Cantu A. (1998). Changes in the breeding bird community of subtropical evergreen forest in the Lower Rio Grande Valley of Texas, 1970s-1990s. Texas Journal of Science. vol 50, no 2. p. 123-132.

Carter MD. (1986). The Parasitic Behavior of the Bronzed Cowbird Molothrus-Aeneus in South Texas USA. Condor. vol 88, no 1. p. 11-25.

Chace JE. (2005). Host use by sympatric cowbirds in southeastern Arizona. Wilson Bulletin. vol 117, no 4. p. 375-381.

Chace JF. (2004). Habitat selection by sympatric brood parasites in southeastern Arizona: The influence of landscape, vegetation, and species richness. Southwestern Naturalist. vol 49, no 1. p. 24-32.

Clotfelter ED. (1995). Courtship displaying and intrasexual competition in the bronzed cowbird. Condor. vol 97, no 3. p. 816-818.

Clotfelter ED & Brush T. (1995). Unusual parasitism by the bronzed cowbird. Condor. vol 97, no 3. p. 814-815.

del Villar-Gonzalez D, Villanueva-Jimenez JA & Martinez-Becerril C. (2006). Neem (Azadirachta indica) ethylic ether extracts on brown rice as feeding deterrent in the control of bronzed red-eyed cowbird (Molothrus aeneus). Agrociencia. vol 40, no 2. p. 197-203.

Dugand A & Eisenmann E. (1983). Rediscovery of and New Data on Molothrus-Armenti. Auk. vol 100, no 4. p. 991-992.

Easterla DA. (1972). Bronzed Cowbird in West Texas and 2 Bill Abnormalities. Southwestern Naturalist. vol 17, no 3. p. 293-295.

Ellison K, Sealy SG & Gibbs HL. (2006). Genetic elucidation of host use by individual sympatric bronzed cowbirds (Molothrus aeneus) and brown-headed cowbirds (M-ater). Canadian Journal of Zoology. vol 84, no 9. p. 1269-1280.

Flood NJ. (1990). ''Aspects of the Breeding Biology of Audubon's Oriole. Journal of Field Ornithology. vol 61, no 3. p. 290-302.

Friedmann H. (1971). Further Information on the Host Relations of the Parasitic Cowbirds. Auk. vol 88, no 2. p. 239-255.

Friedmann H & Kiff LF. (1985). The Parasitic Cowbirds and Their Hosts. Proceedings of the Western Foundation of Vertebrate Zoology. vol 2, no 4. p. 225-302.

Friedmann H, Kiff LF & Rothstein SI. (1977). A Further Contribution to Knowledge of the Host Relations of the Parasitic Cowbirds. Smithsonian Contributions to Zoology. vol 235, p. 1-75.

Garrett KL & Molina KC. (2005). A field observation of the head-down display in the Bronzed Cowbird. Wilson Bulletin. vol 117, no 4. p. 410-412.

Hudon J & Muir AD. (1996). Characterization of the reflective materials and organelles in the bright irides of North American blackbirds (Icterinae). Pigment Cell Research. vol 9, no 2. p. 96-104.

Johnson RR & Roer B. (1968). Changing Status of the Bronzed Cowbird in Arizona USA Tangavius-Aeneus Winter Range. Condor. vol 70, no 2.

Kiff LF. (1973). New Host Records for the Bronzed Cowbird. Wilson Bulletin. vol 85, no 2. p. 240-242.

Kostecke RM, Ellison K & Summers SG. (2004). Continued range expansion by bronzed cowbirds in the southwestern United States. Southwestern Naturalist. vol 49, no 4. p. 487-492.

Matteson RE. (1970). Bronzed Cowbird Taken in Florida. Auk. vol 87, no 3.

McKay CR. (1994). Brown-headed cowbird in Strathclyde: New to Britain and Ireland. British Birds. vol 87, no 6. p. 284-288.

Meanley B & Royall WCJ. (1976). Nationwide Estimates of Blackbirds and Starlings. Proceedings Bird Control Seminar. vol 7, p. 39-40.

Mermoz ME & Ornelas JF. (2004). Phylogenetic analysis of life-history adaptations in parasitic cowbirds. Behavioral Ecology. p. 2004.

Niles DM. (1970). A Record of Clutch Size and Breeding in New-Mexico for the Bronzed Cowbird. Condor. vol 72, no 4. p. 500-501.

Oliphant LW. (1988). Cytology and Pigments of Non-Melanophore Chromatophores in the Avian Iris. In Bagnara, J T (Ed) Progress in Clinical and Biological Research, Vol 256 Advances in Pigment Cell Research; Thirteenth International Pigment Cell Conference, Tucson, Arizona, USA, October 5-9, 1986 Xxv+637p Alan R Liss, Inc: New York, New York, USA Illus 65-82, 1988.

Ortega CP. (1998). Cowbirds and other parasites. In Ortega, C P [Author] Cowbirds and other parasites xix+371p, 1998. University of Arizona Press {a}, 1230 N. Park Avenue, Tucson, Arizona 85719-4140.

Patten MA, Erickson RA & Unitt P. (2004). Population changes and biogeographic affinities of the birds of the Salton Sink, California/Baja California. Studies in Avian Biology. vol 27, p. 24-32.

Peer BD. (2006). Egg destruction and egg removal by avian brood parasites: Adaptiveness and consequences. Auk. vol 123, no 1. p. 16-22.

Peer BD, Ellison KS & Sealy SG. (2002). Intermediate frequencies of egg ejection by Northern Mockingbirds (Mimus polyglottos) sympatric with two Cowbird species. Auk. vol 119, no 3. p. 855-858.

Peer BD, Rothstein SI & Rivers JW. (2005). First record of Bronzed Cowbird parasitism on the Great-tailed Grackle. Wilson Bulletin. vol 117, no 2. p. 194-196.

Peer BD & Sealy SG. (1999). Laying time of the Bronzed Cowbird. Wilson Bulletin. vol 111, no 1. p. 137-139.

Peer BD & Sealy SG. (2000). Responses of scissor-tailed flycatchers (Tyrannus forficatus) to experimental cowbird parasitism. Bird Behavior. vol 13, no 2. p. 63-67.

Peer BD & Sealy SG. (2004). Fate of grackle (Quiscalus spp) defenses in the absence of brood parasitism: Implications for long-term parasite-host coevolution. Auk. vol 121, no 4. p. 1172-1186.

Robbins MB & Easterla DA. (1981). Range Expansion of Bronzed Cowbird Molothrus-Aeneus New-Record for Missouri USA. Condor. vol 83, no 3. p. 270-272.

Rothstein SI. (1978). Geographical Variation in the Nestling Coloration of Parasitic Cowbirds. Auk. vol 95, no 1. p. 152-160.

Sealy SG & Underwood TJ. (2004). Accepters and rejecters of cowbird parasitism in the New World orioles (Icterus spp.). Ornitologia Neotropical. vol 15, no 3. p. 331-347.

Shawkey MD, Hauber ME, Estep LK & Hill GE. (2006). Evolutionary transitions and mechanisms of matte and iridescent plumage coloration in grackles and allies (Icteridae). Journal of the Royal Society Interface. vol 3, no 11. p. 777-786.

Smith PW & Sprunt AI. (1987). The Shiny Cowbird Reaches the USA Will the Scourge of the Caribbean Impact Florida's Avifauna Too?. American Birds. vol 41, no 3. p. 370-371.

Thurber WA & Villeda A. (1980). Notes on Parasitism by Bronzed Cowbirds Molothrus-Aeneus in El-Salvador. Wilson Bulletin. vol 92, no 1. p. 112-113.

Villeda A. (1979). Rufous-Collared Sparrow Zonotrichia-Capensis Victimized by Bronzed Cowbird Molothrus-Aeneus. Wilson Bulletin. vol 91, no 4. p. 628-628.

Warren PS. (2002). Geographic variation and dialects in songs of the Bronzed Cowbird (Molothrus aeneus). Auk. vol 119, no 2. p. 349-361.

Warren PS. (2003). Winter dialects in the bronzed cowbird and their relationship to breeding-season dialects. Animal Behaviour. vol 65, no 6. p. 1169-1178.

Wauer RH. (1973). Bronzed Cowbird Extends Range into the Texas Big-Bend Country. Wilson Bulletin. vol 85, no 3. p. 343-344.

Wauer RH. (1977). Significance of Rio-Grande Riparian Systems Upon the Avi Fauna''. U S Forest Service General Technical Report RM. vol 43, p. 165-174.

External links

Bronzed Cowbird videos on the Internet Bird Collection

Bronzed Cowbird photo gallery VIREO

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article Bronzed Cowbird