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) [XC620044]
by Bernard BOUSQUET from Currais Novos, Rio Grande do Norte, Brazil (call)
Screaming Cowbird (Molothrus rufoaxillaris) [XC84581]
by Jeremy Minns from Aquidauana, MS. Fazenda Aguap\u00e9, Brazil (song, male song)
Subspecies
Analyses of mitochondrial DNA indicate closest relationship with Giant Cowbird (Molothrus oryzivorus) and Bronzed Cowbird (Molothrus aeneus).