Extreme north-western Argentina (Jujuy, Salta), western and eastern Bolivia (south-western La Paz, and from Santa Cruz southern along base of Andes), eastern Paraguay (east of R Paraguay) and south-central and eastern Brazil (southern Mato Grosso, Mato Grosso do Sul, extreme western Paraná and Sío Paulo north to Maranhío and Rio Grande do Norte).
Population
Estimated population is unknown (2010).
Black-capped Antwren (Herpsilochmus atricapillus) [XC556348]
by Mateus Gon\u00e7alves Santos from Fazenda Boa Sorte, Brazil (canto)
Black-capped Antwren (Herpsilochmus atricapillus) [XC717562]
by id from Santa Rita do Novo Destino, Goi\u00e1s, Ch\u00e1cara Jayrson, Brazil (call, song)
Subspecies
Until recently treated as conspecific with Caatinga Antwren (Herpsilochmus sellowi) and Bahia Antwren (Herpsilochmus pileatus). These three are considered to belong to a clade that also includes Creamy-bellied Antwren (Herpsilochmus motacilloides) and Ash-throated Antwren (Herpsilochmus parkeri). Although no geographical subspecies described, plumage and vocal variations exist across its extensive range. Further research is required.
BirdLife International Species Factsheet