Slender-billed Greenbul Stelgidillas gracilirostris Scientific name definitions

c. 18 cm; male 24–37 g, female 26–40 g. A medium-sized, two-toned, slender, relatively long-tailed greenbul. Nominate race has top of head olive-brown, lores and ear-coverts grey, the latter with some paler streaking, inconspicuous narrow grey eyering; upperparts , including uppertail-coverts and tail , olive-brown; flight-feathers dark olive-brown, edged greenish; pale brownish-grey below , paler than side of face, with throat, centre of belly and undertail-coverts even paler, greyish-white, breast and flanks sometimes washed olive; iris deep red, brick-red or red-brown; bill black; legs black or dark brown. Sexes alike, little difference in size. Juvenile resembles adult, but upperparts browner, breast and flanks washed brown, undertail-coverts cinnamon. Race percivali has upperparts more olive-green, less brown, than nominate, underparts paler, more whitish-grey, pale buff towards rear.

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Editor's Note: Additional distribution information for this taxon can be found in the 'Subspecies' article above. In the future we will develop a range-wide distribution article.

Fruits, including berries, and arils, also seeds; also arthropods, including orthopterans, mantids, bugs (Hemiptera), moths (Lepidoptera), caterpillars, ants (Hymenoptera) and spiders (Araneae). Fruits and arils include, in Gabon and PRCongo, those of Allophylus, Croton, Ficus, Heisteria, Macaranga, Morinda, Musanga, Ochthocosmus, Rauwolfia, Xylocopia and, in Rwanda, Agalaea, Bridelia, Harungana, Ilex, Ocotea, Podocarpus, Syzygium, Polyscias, Rutidea, Sapium, Schleffera, Trema, Urera. Usually occurs in pairs or small family groups, sometimes singly; large numbers may gather with other bulbuls in fruiting trees and lianes. Also joins mixed-species flocks, usually keeping to highest levels. Very much a species of tree canopies, usually above 25 m in lowland forest; infrequently comes lower, and then staying within crown of smaller trees and bushes. Forages through leaves and inflorescences for insects and fruit. Unobtrusive and quiet, rather than shy, but often calls while sitting upright in canopy. Estimated size of foraging territory in Gabon 8–12 ha.

Clear, distinctive, downslurred, extended whistle, “tseeeeu” or “peeuuu”, repeated frequently ; also has more rarely used song of 4–5 whistled notes, “whee-ti-twheew-ti-whee” or “whuut-héét whuut-héét whuut-héét”. Contact call a soft “frue” or “fu-wuwu”; alarm call an agitated “chewi” or “chew-chew”.