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Molothrus bonariensis

(Gmelin, 1789)

Shiny Cowbird

G5Secure Found in 2 roadless areas NatureServe Explorer →
G5SecureGlobal Rank
Least concernIUCN
Identity
Unique IDELEMENT_GLOBAL.2.104019
Element CodeABPBXB7010
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVertebrate Animal
IUCNLeast concern
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomAnimalia
PhylumCraniata
ClassAves
OrderPasseriformes
FamilyIcteridae
GenusMolothrus
Other Common Names
Chopim-Gaudério, Azulão (PT) Mirlo, Tordo Común (ES) Vacher luisant (FR)
Concept Reference
American Ornithologists' Union (AOU). 1998. Check-list of North American birds. Seventh edition. American Ornithologists' Union, Washington, D.C. [as modified by subsequent supplements and corrections published in The Auk]. Also available online: http://www.aou.org/.
Conservation Status
Review Date1996-12-04
Change Date1996-12-04
Range Extent>2,500,000 square km (greater than 1,000,000 square miles)
Range Extent Comments
RESIDENT: from eastern Panama south through most of South America to central Chile and central Argentina; during 1900s range expanded though Lesser and Greater Antilles, reaching Puerto Rico in 1955 and Hispaniola in 1970s (AOU 1998, Post and Wiley 1977). Established on Barbados (probably an introduction) and Grenada (AOU 1998). Has reached Cuba, Curacao, and the Bahamas (Derbot and Prins 1992, Carib. J. Sci. 28:104-105; Baltz 1995). Spreading with deforestation along rivers in Amazonia (Ridgely and Tudor 1989). Expansion in range has accompanied large-scale habitat alterations (deforestation) associated with agriculture and animal husbandry (Post and Wiley 1977, Cavalcanti and Pimentel 1988). Now established in southern Florida and occurring rarely to western Florida and southern Georgia, and casually west to central Texas and Oklahoma and north to North Carolina; accidental in Maine (AOU 1998).
Ecology & Habitat

Habitat

Various habitats but prefers open areas (Cruz et al. 1989). Partly open situations with scattered trees, open woodland, cultivated lands, pastures, marshes, and around human habitation (AOU 1983).

Brood parasite and host generalist; lays eggs in nests of many other bird species. In Puerto Rico (and elsewhere), heavily parasitized species include DENDROICA PETECHIA, VIREO ALTILOQUUS, MYIARCHUS ANTILLARUM, and various icterids, including ICTERUS DOMINICENSIS and AGELAIUS XANTHOMUS (Wiley 1985, Post et al. 1993). See Cavalcanti and Pimentel (1988) for hosts in central Brazil.

Ecology

Implicated in decline of several island bird populations, including yellow-shouldered blackbird in Puerto Rico. Other host species that should be monitored for possible cowbird-induced decline include Puerto Rican flycatcher, black-whiskered vireo, black-cowled oriole, and troupial (Cruz et al. 1989). Brood parasitism reduces nesting success and productivity of hosts (Wiley 1985).

Roosts communally in large numbers (1000s in Puerto Rico) with AGELAIUS XANTHOMUS and QUISCALUS NIGER (Post and Wiley 1977); otherwise occurs alone or more frequently in small loose groups. Females commuted daily about 4 kilometers between feeding and breeding areas (Woodworth 1993).

Reproduction

In Puerto Rico, lays eggs mainly March-July (Wiley 1988). In nests of AGELAIUS XANTHOMUS, lays 2-5 eggs per nest (Post and Wiley 1977). Incubation and rearing of young by host species; up to 3-4 cowbirds may fledge from nest of certain hosts (Wiley 1985).
Terrestrial Habitats
Woodland - HardwoodSavannaGrassland/herbaceousCropland/hedgerowSuburban/orchard
Palustrine Habitats
HERBACEOUS WETLANDRiparian
Other Nations (1)
United StatesN2N,N3B
ProvinceRankNative
GeorgiaSNAYes
AlabamaSNRMYes
FloridaS4Yes
North CarolinaSNAYes
Roadless Areas (2)
Puerto Rico (2)
AreaForestAcres
El Toro AreaCaribbean National Forest12,584
Mameyes AreaCaribbean National Forest11,150
References (47)
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  2. American Ornithologists' Union (AOU). 1989. Thirty-seventh supplement to the American Ornithologists' Union Checklist of North American birds. Auk 106:532-538.
  3. American Ornithologists' Union (AOU). 1998. Check-list of North American birds. Seventh edition. American Ornithologists' Union, Washington, D.C. [as modified by subsequent supplements and corrections published in <i>The Auk</i>]. Also available online: http://www.aou.org/.
  4. Astie, A. A. and J. C. Rebora. 2005. Creamy-bellied Thrush defenses against Shiny Cowbird parasitism. Condor 107:788-796.
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  6. Baltz, M.E. 1995. First records of the Shiny Cowbird (MOLOTHRUS BONARIENSIS) in the Bahama Archipelago. The Auk 112(4):1039-1041.
  7. BirdLife International. 2004b. Threatened birds of the world 2004. CD ROM. BirdLife International, Cambridge, UK.
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