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) [XC396450]
by JAYRSON ARAUJO DE OLIVEIRA from Antumapu, La Pintana, Santiago, Regi\u00f3n Metropolitana, Chile (call)
Screaming Cowbird (Molothrus rufoaxillaris) [XC707262]
by JAYRSON ARAUJO DE OLIVEIRA from Itacarambi, State of Minas Gerais, Brazil (song)
Subspecies
Analyses of mitochondrial DNA indicate closest relationship with Giant Cowbird (Molothrus oryzivorus) and Bronzed Cowbird (Molothrus aeneus).