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) [XC746478]
by JAYRSON ARAUJO DE OLIVEIRA from Reserva do Setor S\u00edtio de Recreio Cara\u00edbas-Goi\u00e2nia, Goi\u00e1s, Brazil (call, song)
Screaming Cowbird (Molothrus rufoaxillaris) [XC547928]
by JAYRSON ARAUJO DE OLIVEIRA from Laurentino, Santa Catarina, Brazil (call)
Subspecies
Analyses of mitochondrial DNA indicate closest relationship with Giant Cowbird (Molothrus oryzivorus) and Bronzed Cowbird (Molothrus aeneus).