Black-bellied Tanager (also known as Huallaga Tanager) is a red and black or brown bird with a mostly silver beak. Like other members of the genus Ramphocelus, the base of the mandible is enlarged and colored silvery white. This species is sexually dimorphic. The male has black wings, tail, and belly, with bright red flanks and rump, and a reddish brown head, breast, and back. The female has reddish brown upperparts and tawny reddish underparts and face. The scientific name, Ramphocelus melanogaster, comes from several Greek words, and these words describe the bird’s appearance. The generic name is derived from ramphos, which means bill, and koilos, which means concave or curved. The species name is formed from melas, meaning black, and gaster, which means belly (Jobling 2010), and describes the pattern of the male plumage.
Black-bellied Tanager is very similar to Silver-beaked Tanager (Ramphocelus carbo) in terms of color and behavior, as well as song (Isler and Isler 1987). The best way to tell the difference between the two is the coloration pattern on the back, flanks, and belly. The male of Black-bellied Tanager has bright red flanks and rump; male Silver-beaked Tanager has a reddish brown throat and breast, but the flanks and rump are blackish brown (Ridgely and Tudor 1989, Schulenberg et al. 2010). Females of the species are much more similar to one another, and can not always be distinguished, but female Black-bellied tends to have a brighter red rump, a redder tone to the underparts, greater contrast between the brown throat and reddish breast and belly, and has a reddish cast to the face (Ridgely and Tudor 1989, Schulenberg et al. 2010). The two species mostly geographically replace each other but the distributions closely approach one another or locally overlap (Isler and Isler 1987, Schulenberg et al. 2010).
The following description refers to the nominate subspecies, melanogaster, and is based on Hilty (2011); for other subspecies, see Geographic Variation.
Male: The male has a dark red or reddish brown head and breast that fades to black on the back, wings, and tail. The rump and uppertail coverts are bright red. The flanks are bright red, but are separated by a broad line of black that runs down the center of the belly.
Female: The female is duller than the male, and has no black in the plumage. The upperparts and throat and breast generally are reddish brown or dusky reddish brown, with a redder rump and uppertail coverts. The lower breast and belly are cinnamon red, rather sharply separated from the browner throat and upper breast; the female has no dark patch on the belly. The area of the face surrounding the base of the bill, extending to the ocular region, often is a paler red.
Juvenile: No information available.
Tanagers that have been studied have either a Complex Basic Strategy or Complex Alternative Strategy (Ryder and Wolfe 2009). However, most tanagers only molt once a year (Isler and Isler 1987), and this prebasic molt likely occurs after the breeding season (Isler and Isler 1987, Ryder and Wolfe 2009). Many species have been found to breed in subadult plumage (Isler and Isler 1987). More specific information on molt and its timing is not available for Ramphocelus melanogaster.
Iris: Reddish brown (Hilty 2011).
Bill: Thick, decurved; maxilla dusky, mandible is silvery white with darker tip or duller, bluish gray in females (Hilty 2011).
Tarsi and toes: Dusky gray (Hilty 2011).
Total length: 16-18 cm (Schulenberg et al. 2010), 17 cm (Isler and Isler 1987), 18 cm (Clements and Shany 2001)
Mass: 25 g (n = 1, male; Isler and Isler 1987)