Plain-breasted piculet endemic to South America on the eastern side of the Andes where it lives in the western part of the Amazon basin. The species is present in southern Colombia, eastern Ecuador, Peru and western Brazil at altitudes of up to . It is found in open parts of humid lowland forests, flooded forests, riverside corridors, swamps, thickets and groves, and logged areas with secondary growth and wooded pastures. It often occurs in areas of young "Cecropia" and "Mimosa" trees. The plain-breasted piculet is usually seen by itself or in pairs, but it will occasionally joins small flocks of birds of
White-barred piculet northeastern Brazil; "P. c. thamnophiloides" found in southeastern Bolivia and northeastern Argentina; "P. c. tucumanus" found in northwestern Argentina; the Pilcomayo piculet, "P. c. pilcomayensis" found in southeastern Bolivia, Paraguay and northeastern Argentina; and the nominate subspecies "P. c. cirratus" found in southeastern Brazil, southern Mato Grosso and eastern Paraguay. The taxonomy of this species is difficult; the races "pilcomayensis", "thamnophiloides" and "tucumanus" intergrade in northern Argentina and are sometimes considered a separate species, and "pilcomayensis" intergrades with "cirratus" in eastern Paraguay. The northern subspecies, "confusus" and "macconnelli" may also be a distinct species. The white-barred piculet also hybridizes widely