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) [XC84582]
by Rafael Antunes Dias from Barra do Quara\u00ed, Brazil (song, male song)
Screaming Cowbird (Molothrus rufoaxillaris) [XC524345]
by Dante Buzzetti from Setor Samambaia, mata seca, perto da UFG-Agronomia, Goi\u00e2nia-Goi\u00e1s, Brazil (flight call, song)
Subspecies
Analyses of mitochondrial DNA indicate closest relationship with Giant Cowbird (Molothrus oryzivorus) and Bronzed Cowbird (Molothrus aeneus).