Sulphur-rumped Tanager Heterospingus rubrifrons Scientific name definitions

The Sulphur-rumped Tanager is found over the Caribbean slope of southern Central America between Costa Rica and Panama, where it is an inhabitant of forest and wooded areas, including clearings, and is found to approximately 900 m. Usually found in pairs or small (presumably family) groups, which may at least briefly consort with mixed-species flocks. The sexes are alike, being largely grayish over most of the head and body, with an obvious, large yellow rump patch, and white patches at the sides of the breast. It is unlikely to be mistaken for any other species, especially given that the Scarlet-browed Tanager (Heterospingus rubrifrons) is wholly allopatric; in any case, males of the latter species are wholly distinctive.

15 cm; 36–40 g. Rather large, dull, heavy-billed tanager, with long bill slightly hooked at tip. Male has head , neck and upperparts to back dark leaden grey, yellow rump (often hidden by folded wings); uppertail-coverts olive-green, tail and upper­wing, including coverts, dusky; throat and underparts  grey, somewhat paler than above, white pectoral tufts (usually protruding from beneath wing), undertail-coverts olive-green with some admixed yellow; axillaries and underwing-coverts white; iris dark red to reddish-brown; bill blackish; legs blue-grey. Female like male, but may lack olive on uppertail-coverts, and belly often tinged brownish. Immature is similar to adult, but duller, more sooty above and olive-tinged below, wing-coverts edged dull olive, yellow rump patch like adult’s but smaller.

Caribbean slope from Costa Rica (Limón) E to NE Panama (E to Puerto Obaldía, in San Blas); locally on Pacific slope of Panama in Veraguas (sight record) and Panamá Province (Cerro Jefe, Cerro Azul, Cerro Chucantí), also in extreme W Darién.

Fruit , and large and small arthropods. Fruit includes Cecropia, Hamelia, and mistletoe berries (Loranthaceae). Occurs in pairs and in small family groups, rarely in larger groups (up to 14 seen together). May accompany mixed-species flocks, especially with groups of Black-faced Grosbeaks (Caryothraustes poliogaster) and Chrysocorypha delatrii, and also with mixed groups containing Tangara species, honeycreepers and dacnises; also frequently forages away from mixed flocks, in part because of faster speed at which it travels when foraging. Forages in canopy and upper levels, also lower along forest borders. Of 98 observations of foraging, 42% were in treetops, 37% at middle heights and 21% low. Of 24 observed cases of insect-hunting, 50% were from foliage, all from the tops of leaves. Seen to lean downwards to examine sides of branches in Costa Rica.

Call  a thin “tsip” or “tseet”, singly or sometimes in rapid, squeaky or twittery series  ; in flight repeats a thin “seet” or “silt”; in Costa Rica a sharp, buzzy “dzeet”, and a higher, thinner “tseet” in flight. Song not recorded.