Sao Tome Oriole Oriolus crassirostris Scientific name definitions

23–24 cm; 50 g. A “washed-out” version of mainland orioles, and with more robust bill. Male has head and neck to breast black, throat freckled with white; mantle pale yellow, broadly streaked olive-grey, back greyish olive-green, rump paler with whitish patch at side; primaries narrowly edged white and with broad white crescent at tips, outer webs of secondaries blue-grey with white edges and tips, tertials grey-green, primary coverts black with white tips (forming conspicuous white patch on closed wing); uppertail has central feathers dark olive, others black with long yellow tips, amount of yellow increasing towards outer feathers, underside of tail bright yellow; belly and flanks white, mottled grey, vent and undertail-coverts pale yellow; iris red; bill dull carmine or brownish-red; legs grey. Female is like male, but head slightly paler, cheek streaked with white, chin to breast greyish-cream, broadly mottled dark, merging into greyish-white or greyish-cream on belly; underside of tail is pale yellowish-olive. Immature has head and mantle olivaceous dark grey, back and rump greener than adult, chin and throat whitish, mottled at side, breast whitish, strongly streaked dark, belly creamy white; wings browner and less patterned, no wing patch.

NW, C & S São Tomé I, in Gulf of Guinea.

Inhabits primary forest up to 1600 m, also mature secondary forest and forest edge; sometimes in dry forest in N. Generally absent from cocoa plantations and from vicinity of human habitations.

Resident; may wander locally.

Fruits, seeds; also invertebrates, e.g. hemipteran bugs, larval and adult beetles (Coleoptera). Forages alone or in pairs, from middle storey to canopy; sometimes joins mixed-species flocks.

Whistled song  very variable, a long, mellow downslurred “tyeeow”, “way-whee-ya”, “chip-aw-hah-aw” or “hik-kuway-kuwow” or an ascending “ko-ku-waayoo”; slower and deeper than those of other African orioles, richer and mellower than songs of other members of “African black-headed group”. Scolding call  a high-pitched, harsh “keea”, shorter than equivalent calls of congeners.

Breeds at least Aug–Jan, possibly as early as Jun and as late as Feb, as young observed in early Jul and Feb and juveniles during Jul–Aug and Dec–Mar, also a male with well-developed gonads in Feb. One nest, built by one individual in Sept, an open cup suspended hammock-like between two horizontal branches at height of 9 m; another was made out of leaves and shredded vegetation, and suspended between two twigs near leafy end of branch 11 m above ground. No other information.

VULNERABLE. Restrictedrange species: present in São Tomé EBA. Locally common in primary forest. Total population thought to be fewer than 1000 individuals, confined to c. 480 km² of suitable primary and mature secondary forest habitat. Recent surveys suggest it may occur at higher densities than previously believed, i.e. 0·2–0·7 birds/ha in central montane and high-altitude mist forests, and 3·2 birds/ha in remaining areas of lowland forest in SW. Historically, large areas of forest were cleared for cocoa and coffee plantations, and intact forest remains mostly at higher elevations. Before independence of São Tomé, in 1975, plantations were frequently sprayed with pesticides, causing apparently drastic decrease in oriole numbers. Since then, many plantations have reverted to secondary growth, but recent land privatization and reintensification of agriculture may have led to increase in number of small farms, pesticide use and clearance of trees, while road developments along E & W coasts are facilitating access to previously remote areas. Protection of primary forest as a zona ecológica and a national park has been proposed, while a new law providing for the listing of protected areas and the protection of threatened species awaits final ratification. Improved knowledge of the species’ numbers and habitat requirements may result in its population estimate being revised upwards and its threatened status being reviewed.