Blue-throated Roller
Eurystomus gularis
A large-billed roller of primary and secondary forests that is often found sitting on branches overlooking clearings or in the canopy. Distinctive, with a bronze-colored body, a blue throat, a pale yellowish bill, and blue tail and flight feathers. Resembles and occurs alongside the related Broad-billed Roller, but Blue-throated Roller differs in its blue throat and bronzier body. Voice is a harsh “kleek,” often delivered noisily in rapid succession.
识别特征
The blue-throated roller is a dumpy, large-headed, thick-necked bird that frequents the tops of trees. Overall, it is a dark bird, mainly chestnut brown with a bright yellow bill and a blue patch on the throat, a blue tail and purplish blue wings. The juvenile shows bluish on the underparts. It is a rather long-winged roller and can give a falcon like silhouette in flight. It measures 25 cm in length; the males weigh 82–117.5 g, the females 88–108g.
分类信息
The blue-throated roller was formally described in 1819 by the French ornithologist Louis Pierre Vieillot under its current binomial name Eurystomus gularis. The specific epithet gularis is Modern Latin meaning "-throated". Vieillot based his description on a specimen in the Muséum National d'Histoire Naturelle in Paris which he mistaken believed had been collected in "Australasie"; the type locality has been designated as Senegal. A molecular phylogenetic study published in 2018 found that the blue-throated roller was most closely related to the broad-billed roller (Eurystomus glaucurus).<p>Two subspecies are recognized:
- 学名
- Eurystomus gularis
- 命名信息
- Vieillot, 1819
- 目
- Coraciiformes
- 科
- Coraciidae
- 属
- Eurystomus
分布与栖息地
The blue-throated roller occurs in western sub-Saharan Africa from Guinea to Cameroon, south to northern Angola, and west to south-eastern Uganda. It is also found on Bioko Island.<p>The blue-throated roller tends to remain high up in the tops of trees and hunts above the canopy of primary and secondary rainforest, plantations, gallery forests and relict forest patches in cleared regions. They prefer clearings, riversides and giant emergent trees.
- 迁徙
- Resident species
行为
The blue-throated roller perches high up, either singly or in pairs, on bare branches, frequently at the very top of the canopy. They often sit for long periods, and sometimes make their shrill chattering calls. When active they hawk insects in the air and aggressively defend their territory from other bird species. In the late afternoon the birds gather in small flocks, often mixed with broad-billed rollers, to feed on ants and termites which emerge after a rainfall. The rollers feed on these insects in flight, acrobatically chasing them and eating them on the wing. This activity continues until dusk and one roller may eat over 700 insects weighing 40g.<p>The blue-throated roller is a territorial species when breeding and both courtship and territorial defence involve noisy aerial chases. The nest is an unlined cavity, normally about 10m up the trunk of a tree on the edge of a clearing; 2-3 eggs are laid with laying recorded in February to March in the Ivory Coast, February to April in Ghana, April and September in Nigeria, January in Gabon, and April and October in the Democratic Republic of Congo.
保护状况
- 种群趋势
- declining
照片
分布
鸟叫声
其他鸟类
Tricolored Parrotfinch
Erythrura tricolor
A small blue finch with conspicuous red tail and an emerald-green back. Females duller, with green extending to nape. Juveniles dull green, with gray head and pale bill, but still show red tail. Singles, pairs, or flocks feed on or near the ground in forests, open woodlands, and thickets within the lowlands and mountains. An undescribed parrotfinch has been documented on Mount Mutis in Timor; Tricolored differs from it in lacking red on the face. Calls include soft, high-pitched “seet” and “sit” notes.
Red-breasted Coua
Coua serriana
Dark, long-tailed, long-legged understory bird. When seen well, the red breast and black face with blue facial skin are distinctive and beautiful. Very shy bird that spends most of its time walking on the forest floor, sometimes hopping into low tangles. Found in eastern rainforest, mainly at low elevations. The most common call is a loud single “treeeeeow.” Slightly larger than Red-capped Coua, with red on the breast rather than the cap. Much longer-tailed than forest-dwelling rails.
Sri Lanka Woodshrike
Tephrodornis affinis
Small gray songbird with heavy bill, dark mask, and white eyebrow. Underparts pale whitish; in flight note white rump. Inhabits wooded areas and scrub in lowland and lower hills, mostly in the Dry Zone of Sri Lanka; avoids dense, wet forests. Arboreal species usually encountered in pairs or small groups. Pale eyebrow and plain underparts aid identification from similarly heavy-billed (but larger) Large Woodshrike. Vocalizations include soft “chup” notes; song a resonant series, “wee-wee-weet-weet”, accelerating then decelerating. Varies in rapidity of notes and number of notes in series.
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