About Willisornis poecilinotus (Cabanis, 1847)
The common scale-backed antbird, scientific name Willisornis poecilinotus (Cabanis, 1847), measures 12 to 13 cm (4.7 to 5.1 in) long and weighs 15 to 22 g (0.53 to 0.78 oz). For the nominate subspecies W. p. poecilinotus, adult males are mostly gray, with darker upperparts than underparts. They have a white patch between their scapulars, and black patches edged with white on their lower back – this marking gives the species its common English name. Their wings and tail are black, with white edges and tips on many feathers. Adult females of the nominate subspecies have a reddish yellow-brown crown and face. Their upperparts are mostly olive-brown, with brownish black patches edged with buff on the lower back. They also have a white patch between the scapulars. Their flight feathers are blackish brown with reddish brown edges, and their tail is dark olive-brown with white spots and a blackish band near the end. Their throat is pale grayish white, their underparts are gray, and their flanks have a reddish yellow-brown tinge. Different subspecies show distinct plumage variations in females: females of W. p. duidae have a black lower back and rump with wide white feather edges, a black tail with white spots, reddish yellow-brown underparts with a cinnamon-rufous center to the belly, and olive-brown tinged flanks. Females of W. p. lepidonota are similar to W. p. duidae females but paler, with a browner crown and a light buff center to the belly. Females of W. p. griseiventris have a rufous-buff face, plain lower back and rump, a pale gray throat, and gray underparts. Males of W. p. gutturalis have a black throat; females of this subspecies resemble female W. p. lepidonota but have a pale olive center to the belly. The subspecies of the common scale-backed antbird have separate distributions across northern South America: W. p. poecilinotus is found in central and southeastern Venezuela, the Guianas, and northeastern Brazil from Roraima to Amapá. W. p. duidae occurs in east-central Colombia, southwestern Venezuela, and northwestern Brazil along the Rio Negro. W. p. lepidonota is found in southeastern Colombia, eastern Ecuador, and northeastern and east-central Peru. W. p. griseiventris ranges across south-central and southeastern Peru, northern Bolivia, and southwestern Amazonian Brazil between the rios Juruá and Madeira, south into western Mato Grosso. W. p. gutturalis is found in northeastern Peru and western Amazonian Brazil as far as the Rio Juruá. The common scale-backed antbird primarily inhabits the understorey of humid terra firme evergreen forest, and it also occurs in várzea and igapó forest. Elevation limits vary by region: it reaches 1,350 m (4,400 ft) in Brazil, 1,300 m (4,300 ft) in Venezuela, and 800 m (2,600 ft) in Colombia. In Ecuador, it mostly occurs below 700 m (2,300 ft) but can reach up to 1,100 m (3,600 ft). In Peru, it occurs locally up to 1,350 m (4,400 ft) but is mostly found below 900 m (3,000 ft).
