The Flame-rumped Tanager belongs to order Passeriformes, family Thraupidae and genus Ramphocelus (ramphos=bill; koilos=concave; Jobling 2010), as can be deduced from its silver-colored strong bill (Ridgely and Tudor 1989). Ramphocelus flammigerus (flamma=flame; gerere=to carry; Jobling 2010) is characterized by its bright colored rump and includes two distinctive subspecies: Ramphocelus flammigerus flammigerus and Ramphocelus flammigerus icteronotus. Each of these subspecies is sometimes considered its own species (Bedoya and Murillo 2012). The bill of the Flame-rumped Tanager has a black tip and its plumage is velvety black for the most part in males, with the exception of the red rump. Females have a brownish-black plumage on their head, back and tail, and a bright colored region that extends to their lower back, rump and belly. The black or brown on their plumage is usually contrasted with bright colors that range from red to yellow, with orange being the most common rump color. Notably, the females have a diffused orange band across their breast and in transitional areas where the bright coloration turns to dark black or brown. In the Lemon-rumped subspecies (R. f. icteronotus), the rump in males and the rump, lower back and belly in females are exclusively of a pale yellow color. Females tend to have a lighter grey or olive coloration above and do not have an orange band across their breast. Interestingly, the Flame-rumped Tanager is an exception within its group due to the females having a more complex plumage than the males (Ridgely and Tudor 1989). Hybrids between both subspecies are quite common. Males often present an orange rump and females present a very diffused and non-obvious breast bands (Bedoya and Murillo 2012).
Flame-rumped and Lemon-rumped Tanagers can be easily distinguished from all other bird species. The male Flame-rumped shares a similar coloration with the male Scarlet-rumped Tanager (Ramphocelus passerinii) but they can be distinguished by the extent of the bright red region, which encompasses the lower back, tail coverts and rump in the Scarlet-rumped (Ridgely and Tudor 1989). Despite their similar common names, the Sulphur-rumped Tanager is not morphologically very similar, being mostly gray (Plath 1946).
It might be difficult to determine if an individual should be considered a Flame-rumped or a Lemon-rumped as a consequence of the high frequency of hybridization and intermediate forms (Bedoya and Murillo 2012). They are sometimes considered full species (Hilty 2011), but are usually considered conspecifics of the same species (Ridgely and Tudor 1989, Dickinson and Christidis 2014, Clements et al. 2015).
The following description refers to the nominate subspecies, Ramphocelus flammigerus flammigerus; for the other subspecies, see Geographic Variation.
Adult male: Velvety black plumage with a bright orange-red lower back and rump, reason for which it is commonly known as Flame-rumped Tanager (Meyer de Schauensee 1966).
Adult female: lower back and rump as in male, but blackish brown on back and yellow breast and upper back with orange-red bands across breast (Meyer de Schauensee 1966).
Juvenile/subadult: Similar to adult female, but undertail coverts are marked with brownish black (Wetmore et al. 1984).
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). Although a subadult/juvenile plumage is described for Ramphocelus flammigerus (Wetmore et al. 1984), more specific information on molt and its timing is not available for this species.
Iris: red (Ridgely and Tudor 1989)
Bill: bluish grey or silvery with black tip (Ridgely and Tudor 1989, Burton 1975)
Tarsi: bluish grey or silvery (Ridgely and Tudor 1989, Burton 1975)
Total length: 18-18.5 cm (Restall et al. 2007) or 19.7-20.9 cm (Isler and Isler 1987) or 16.51-18.5 cm (Plath 1946) or 15.7-17.6 cm (Bedoya and Murillo 2012).
Linear measurements: (from Wetmore et al. 1984):
•Wing length, males: mean 82 mm (range 79.1-84.0 mm, n=10)
•Wing length, females: mean 77.6 mm (range 71.2-82.1 mm, n=10)
•Tail length, both sexes combined: range 68.7-82.7 mm, n=66 (Bedoya and Murillo 2012)
•Tail length, males: mean 69.4 mm (range 67.0-74.4 mm, n=10),
•Tail length, females: mean 67.9 mm (range 64.6-71.4 mm, n=10)
•Culmen (from base), males: mean 17.0 mm (range 16.0-18.2 mm, n=10)
•Culmen (from base), females: mean 16.6 (range 15.0-18.0 mm, n=10)
•Tarsus, males: mean 23.7 mm (range 22.8-24.6 mm, n=10)
•Tarsus, females: mean 23.0 mm (range 21.8-24.2 mm, n=10)
•Bill width, both sexes combined: range 8.0-9.4 mm, n=66 (Bedoya and Murillo 2012)
•Mass: both sexes and subspecies combined, mean 45g (Dunning 2008) or 33g (range 29.6-35.6g; Hartman 1955)
-Male: 40-45.1g (n=10; Sibley 1958)
-Female: 35.1-38g (n=4; Sibley 1958)