South-eastern Bolivia and central Brazil (southern from Mato Grosso, southern Tocantins, Goiás, and western Minas Gerais), southern throughout Paraguay and Uruguay to north-eastern and central Argentina (south to Río Negro and north-eastern Chubut).
 
Population
Estimated population is unknown (2010).
Screaming Cowbird (Molothrus rufoaxillaris) [XC49284]
by Rosendo Fraga from Estancia La Candelaria, Buenos Aires, Argentina (song)
Screaming Cowbird (Molothrus rufoaxillaris) [XC534153]
by Rosendo Manuel Fraga from Rio Sucuri\u00fa, Tr\u00eas Lagoas, Mato Grosso do Sul, Brazil (begging call, call)
Subspecies
Analyses of mitochondrial DNA indicate closest relationship with Giant Cowbird (Molothrus oryzivorus) and Bronzed Cowbird (Molothrus aeneus).