Barbets are stout birds with heavy bills, and usually have brightly colored plumage. The upperparts of Black-girdled Barbet are black, with a large white or yellow white spots on each side of the back and on the tertials and inner secondaries, and white or yellow white uppertail coverts. The throat is brown; the breast is white, bordered below by a black band that crosses the belly (the black girdle); the lower belly is whitish, with red undertail coverts. The sexes are similar, but the male has a bright red crown and nape; the top of the head is black in the female.
The striking black and white plumage of Black-girdled Barbet is unique among Amazonian barbets. Other black and white Capito, such as Spot-crowned Barbet (Capito maculicoronatus), Orange-fronted Barbet (Capito squamatus), White-mantled Barbet (Capito hypoleucus), and Five-colored Barbet (Capito quinticolor), occur only in northwestern South America, and none has the black belly band of Black-girdled Barbet.
The following detailed description is based on Cherrie (1916) and on Short and Horne (2001):
Adult male: Very narrow black line above the bill, connecting to the lores and to a narrow black line just above the eye. Otherwise, forecrown, crown and nape bright scarlet red. Sides of the head black. Back black, except for white or yellowish white scapulars. Uppertail coverts pale olive green. Wings black, the outer webs of the tertials and inner secondaries yellowish white. Rectrices black. Chin and throat tawny olive, cinnamon, or brown. Upper breast white or buffy white, becoming pale greenish yellow on the belly. Flanks black, the black extending medially as a band across the lower breast, this band not quite meeting in the center. Tibial feathers dull green. Undertail coverts scarlet red, the longest feathers tipped with dull green.
Adult female: Similar to adult male, but the crown and nape are black.
Immature: Throat whiter, less dark brown; black of plumage is duller and browner; the red of the undertail coverts is paler, and barred with yellow; and the rectrices are more pointed. In its first plumage, the male may have a black crown.
Very little information, apart from "late breeding and post-breeding moult Aug-Nov, Feb-Apr, June" (Short and Horne 2001).
Iris: dark brown
Bill: pale greenish gray, or maxilla greenish white, mandible light bluish gray tipped greenish white
Tarsus and toes: greenish gray, olive gray
Bare parts color data from Cherrie (1916) and personal observation.
Total length: 18 cm (van Perlo 2009)
Linear measurements (from Short and Horne 2001):
wing length, male: mean 88.7 mm (range 84.5-97.0 mm, n = 22)
female: mean 87.3 mm (range 82.5-91.0 mm, n = 23)
tail length, male: mean 52.1 mm (range 48.0-57.0 mm, n = 22)
female: mean 51.8 mm (range 48.7-59.9 mm, n = 24)
bill length, male: mean 22.38 mm (range 20.0-24.1 mm, n = 26)
female: mean 22.21 mm (range 20.2-23.7 mm, n = 25)
tarsus length, male: mean 22.66 mm (range 20.2-25.0 mm, n = 25)
female: mean 22.86 mm (range 21.4-25.0 mm, n = 25)
Mass: male, mean 67.2 g (range 56-74 g, n = 11; Short and Horne 2001)
female, mean 67.2 g (range 57-70 g, n = 13; Short and Horne 2001)