Family New World Blackbirds (Icteridae)

Least Concern

Shiny Cowbird (Molothrus bonariensis)


French: Vacher luisant German: Seidenkuhstärling Spanish: Tordo renegrido

Tanagra bonariensis

J. F. Gmelin

, 1789,

Buenos Aires, Argentina


Proposed race melanogyna (Paraná, Brazil), with females blackish (almost as black as males), now considered a dark morph of nominate, as also is proposed race milleri (Mato Grosso, Brazil). Origin of isolated Chilean population of nominate race uncertain; genetic analysis desirable. Seven subspecies recognized.

Subspecies and Distribution
  • M. b. minimus Dalmas, 1900 – SE USA (Florida), West Indies, Trinidad and Tobago, the Guianas and extreme N Brazil (R Branco).
  • M. b. cabanisii Cassin, 1866 – E Costa Rica, Panama and W Colombia.
  • M. b. venezuelensis Stone, 1891 – N Venezuela and E Colombia.
  • M. b. aequatorialis Chapman, 1915 – SW Colombia and W Ecuador.
  • M. b. occidentalis Berlepsch & Stolzmann, 1892 – extreme SW Ecuador (Loja), W Peru and extreme N Chile (Arica).
  • M. b. riparius Griscom & Greenway, 1937 – E Ecuador, E Peru, and Amazon Valley in Brazil (E to Óbidos, Pará).
  • M. b. bonariensis (J. F. Gmelin, 1789) – C & E Brazil (S of R Amazon) S to E Bolivia, Paraguay, Uruguay and Argentina (S to Chubut); also Chile (Atacama S to Aysén).
  • Descriptive notes

    17–21·5 cm; male average 55·7 g and female 44·9 g (nominate, E Argentina), male average 63·7 g and female 55·6 g (cabanisii... read more


    Male has “gurgling” song with 2–6 low-pitched gurgles followed by thin whistles... read more


    Found in almost all open habitats, avoiding unbroken forest and dense woodland. Habitats include... read more

    Food and feeding

    Diet mostly insects and seeds. Feeds on both wild and cultivated seeds. Reported as taking nectar from flowers of the vine Combretum... read more


    Season Mar–Oct in Puerto Rico, May–Sept in Venezuela and Sept–Feb in N half of Argentina. Mating system apparently... read more


    Chiefly resident. In Argentina a partial short-distance migrant, with extensive overlap of breeding... read more

    Status and conservation

    Not globally threatened. Common to very common throughout most of range; uncommon and local in Amazonian lowlands. Rather an aggressively spreading species, thriving in... read more

    Recommended citation

    Fraga, R. (2019). Shiny Cowbird (Molothrus bonariensis). 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 on 14 December 2019).