New World Blackbirds (Icteridae)

Giant Cowbird (Molothrus oryzivorus) - HBW 16, p. 785

French: Vacher géant German: Riesenkuhstärling Spanish: Tordo Gigante
Other common names: Rice Grackle

Taxonomy: O.[riolus] oryzivorus J. F. Gmelin, 1788, Cayenne, French Guiana.
Formerly placed in genus Psomocolax or Scaphidura, but such treatment not supported by molecular-genetic findings. Analyses of mitochondrial DNA indicate closest relationship with M. rufoaxillaris and M. aeneus. Geographical variation weak; further study desirable. Race impacifus commonly emended to “impacificus” but, in absence of any internal evidence in original description (where same original spelling appears three times), there is no justification for such a change under the International Code of Zoological Nomenclature. Two subspecies tentat.. View all taxonomy...

Taxonomy: O.[riolus] oryzivorus J. F. Gmelin, 1788, Cayenne, French Guiana.
Formerly placed in genus Psomocolax or Scaphidura, but such treatment not supported by molecular-genetic findings. Analyses of mitochondrial DNA indicate closest relationship with M. rufoaxillaris and M. aeneus. Geographical variation weak; further study desirable. Race impacifus commonly emended to “impacificus” but, in absence of any internal evidence in original description (where same original spelling appears three times), there is no justification for such a change under the International Code of Zoological Nomenclature. Two subspecies tentatively recognized.

Subspecies and Distribution:

  • impacifus (J. L. Peters, 1929) - E Mexico (Veracruz) S to W Panama.
  • oryzivorus (J. F. Gmelin, 1788) - C Panama E to Colombia, S on Pacific coast to NW Peru (Tumbes), and from Venezuela, Trinidad and Tobago and the Guianas S to E Peru, Bolivia, N & NE Argentina (Jujuy, Salta and N Corrientes) and most of Brazil (S to Santa Catarina; absent in NE).