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) [XC510926]
by GABRIEL LEITE from Barra do Quara\u00ed, Rio Grande do Sul, Brazil (song)
Little Thornbird (Phacellodomus sibilatrix) [XC823469]
by Carlos M. Grassini from Altos de Chipi\u00f3n, San Justo, C\u00f3rdoba, Argentina (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.