Extreme southern Bolivia (south-western Santa Cruz), western Paraguay, northern Argentina (south to eastern La Rioja, northern San Luis, central Córdoba and northern Buenos Aires) and south-western Uruguay.
 
Population
Estimated population is unknown (2010).
Little Thornbird (Phacellodomus sibilatrix) [XC54197]
by Peter Boesman from Isla Vizcaino, Canitas, Rio Negro, Uruguay (song)
Little Thornbird (Phacellodomus sibilatrix) [XC46967]
by Bernabe Lopez-Lanus from Campo Adhemar Dri, 7 Km Sur de Federaci\u00f3n, Entre R\u00edos, AR., Argentina (alarm call, song)
Subspecies
No subspecies.
Considered by some authors to form a superspecies with Rufous-fronted Thornbird (Phacellodomus rufifrons), but the two overlap considerably in distribution, and differ in body size and nest structure.