Comoro Blue-Pigeon
Alectroenas sganzini
Medium-sized chunky pigeon that is dark blue with a pale gray hood. Appears short-tailed in flight. Found in rainforest, secondary habitat, and plantations, and locally in dry coastal scrub. Most common at higher elevations in most of its range. Most often seen perched up conspicuously on emergent trees, feeding on fruiting trees, or in flight in small flocks. The common vocalization is a quick series of low hoots or growls. Dark blue coloration and pale head separate it from all other pigeons in its range.
识别特征
The Comoro blue pigeon measures about 27 centimetres (11 in) in length. The male weighs from 134 to 158 g (4.7 to 5.6 oz), and the female weighs about 117 grams (4.1 oz). It has a silvery gray head, neck, and upper breast. The neck feathers are silvery white in colour, and are very long and deeply partitioned. The beak is greenish or yellowish grey, and has a pale yellow or greenish white tip. It has black lower underparts. The lower part of the breast is shiny violet-blue, and the belly and flanks are more greenish blue in colour.
分类信息
- 学名
- Alectroenas sganzini
- 命名信息
- (Bonaparte, 1854)
- 目
- Columbiformes
- 科
- Columbidae
- 属
- Alectroenas
分布与栖息地
The Comoro blue pigeon is endemic to the Comoros and the coralline Seychelles. Its natural habitats are subtropical or tropical moist lowland forests, subtropical or tropical mangrove forests, and subtropical or tropical moist montane forests. It is found at elevations ranging from 500 to 1,500 m (1,600 to 4,900 ft) above sea level.
- 迁徙
- Resident species
行为
The Comoro blue pigeon is sometimes solitary, but may occur in groups of up to 15 individuals. These often fly about 10 m (30 ft) above the water between islands in the Aldabra group, making regular journeys in one direction in the mornings and back again in the evenings. Their flight is fast, interspersed with wing claps. They have a habit of perching high in a tree in full sun and raising one wing to expose it to the sun. They are arboreal, fruit-eating birds which seem to avoid landing on the ground; however, small stones found in their crop seem to indicate that they do sometimes descend to the earth.
保护状况
As of 2017, the Comoro blue pigeon has been rated as a species of near threatened on the IUCN Red List of Endangered Species. This is because although it has a restricted distribution, its range size is considered to be more than 20,000 km2 (7,700 mi2). Despite a decreasing or fluctuating range, the area of occurrence is above the criterion to warrant it a vulnerable rating. Although its population has not been determined, it is thought to be above 10,000. Also, even though its population is decreasing, the rate of decline is thought to be less than 30% over ten years or three generations and thus is below the vulnerable criteria. It is reportedly extinct in some areas, commonly found in others, and extinct on many small islands.
- 种群趋势
- declining
照片
分布
其他鸟类
Javan Blue-banded Kingfisher
Alcedo euryzona
Very rare, small kingfisher of forested streams and rivers up to the lower mountains. Highly threatened and found at very few remaining sites. Both sexes have silver-blue back and tail, white throat and broad, blue-green breastband. Male has white belly and all-black bill, female has an all-orange belly and red base to lower bill. Distinguished from Common Kingfisher by overall duller, darker coloration and lack of an orange patch behind the eye. Usually higher up than Blue-eared Kingfisher and lacks the bright blue color. Gives a piercing call similar to that of Common Kingfisher.
Black Scimitarbill
Rhinopomastus aterrimus
This all-black bird has a long, slim bill, and a fairly long tail. In flight, white bars across the wings are revealed. Birds in the eastern part of the range also have white in the outer tail, while the western birds have all-black tails. Found in a variety of savanna habitats. The call is a series of fluted, rising “wheet” notes; similar to Common Scimitarbill, but higher-pitched. Also similar in appearance to Common Scimitarbill, but there is little overlap in range, and Black is separated by its straighter bill and slightly shorter and less pointed tail. Separated from woodhoopoes by its shorter, less floppy, and squarer tail.
Straight-billed Woodcreeper
Dendroplex picus
Widespread and fairly common in northern South America. This medium-sized woodcreeper is found in open wooded habitats, scrub, and riparian forest. The well-named woodcreeper has a very straight bill that can even look slightly upturned unlike most other woodcreepers. Also note the bill’s pale color. Otherwise, mostly dark brown with fine streaking on the head and breast, but note the unstreaked back. Very similar to Zimmer’s Woodcreeper, but listen for Straight-billed’s slightly slower song that typically goes up in pitch at the end. Striped Woodcreeper has more streaking on the back and a slightly decurved bill. Usually seen singly or in pairs working up tree trunks and branches, usually at lower to middle levels in forest. Sometimes follows mixed-species flocks.
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