Cuckoo-roller
Leptosomus discolor
A large, big-headed, short-legged bird that is very odd in almost every way, especially in the position of the eye near the top of the head. Males have a pale head and underparts and a colorful iridescent back. Females are rufous brown with heavy spotting below. Found in all forest types, and sometimes in adjacent scrub and plantations. Often perches and feeds in the canopy, though rarely on an emergent branch. Males and pairs frequently make soaring display flights, constantly giving incredibly loud and persistent three-part wailing calls. Much larger than Broad-billed Roller, with a dark bill. Looks raptor-like, but has a huge head, small bill, and less powerful wingbeats.
识别特征
The cuckoo-roller has a total length of 40–50 cm (16–20 in); the nominate subspecies is the largest, and L. d. gracilis the smallest. Unlike the true rollers and ground rollers, where the sexes have identical appearance, the cuckoo-roller is sexually dichromatic. Males have a mostly velvety grey chest and head, changing gradually to white on the remaining underparts (the demarcation between grey and white is stronger in L. d. gracilis). The back, tail, and wing-coverts are dark iridescent green with a purplish tinge (especially on the wing-coverts), and the crown and eye-stripe are black. Females are mostly brown, with strongly dark-spotted pale underparts (less spotting in L. d. gracilis). Juveniles are generally reported as resembling a dull female, but at least juveniles of L. d. gracilis are sexually dimorphic, and this also possibly applies to the other subspecies. The bill is stout and the eyes are set far back in the face. The legs and feet are small, and the feet have an unusual structure which has confused many ornithologists, but is now thought to be zygodactylous (two toes forwards, two toes backwards).
分类信息
- 学名
- Leptosomus discolor
- 命名信息
- (Hermann, 1783)
- 目
- Leptosomiformes
- 科
- Leptosomidae
- 属
- Leptosomus
分布与栖息地
The cuckoo-roller occupies a wide variety of habitats, including altered areas. They inhabit forest, including rainforest, litoral forest, deciduous forest, spiny bush-forest, and tree plantations. In the Comoros, the species is found on all the major islands, particularly in forested zones. It can be found from near sea level up to 2000 m.
- 迁徙
- Resident species
行为
The diet of the cuckoo-roller is not well known, but a 1931 expedition found that chameleons and insects, particularly locusts and caterpillars, are important food items. Stomachs have often been found to be lined with caterpillar hairs, and other prey taken include grasshoppers, cicadas, stick insects, and geckos. The principal foraging technique is to perch motionless, watching for prey, then to make a quick sally towards the prey when observed. They also hunt from the air. Prey is caught in the large bill and killed by beating it against a branch.<p>Very few studies have investigated the breeding habits of the cuckoo-roller. It has been described in the past as a polygamous breeder, but no evidence for this is available. The nest is located in tall trees, 4–6 m (13–20 ft) off the ground, in natural cavities. No lining is placed inside the cavity; the white eggs are laid directly on the bottom. The usual clutch size is around four eggs. Incubation is performed by the female only, while the male feeds her. The incubation period is about 20 days, after which fluffy chicks are born. Chicks remain in the nest for 30 days before fledging.
保护状况
The species is not generally hunted and has proven resistant to habitat change that has threatened other native birds. It is assessed as Least Concern by the IUCN. The distribution of the cuckoo-roller is vast, and populations in Madagascar persist in small forest fragments. Areas with abundant populations include broad expanses of forest associated with reserves such as Zahamena, Andringitra, Andohahela, and Marojejy.
- 种群趋势
- declining
照片
分布
鸟叫声
其他鸟类
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Bolemoreus hindwoodi
Medium-sized honeyeater recorded at higher elevations in the ranges behind Mackay in central Queensland. Gray overall; underparts slightly paler, with fine streaks on chest difficult to see. Dark cheeks split by a thin white gape mark that wraps back under and behind the bluish eye; also has a faint, narrow neck plume. Call is a series of sharp, frantic-sounding whistles.
Andean Hillstar
Oreotrochilus estella
Small hummingbird of the high Andes; found in rocky and shrubby valleys, villages, and any open and semiopen areas with flowers. Often builds nest under eaves of buildings or bridges: a bulky cup of plant material and alpaca wool to insulate against cold nights. Fairly common. Readily identified in most of range by its extensively white tail. Male has an emerald green gorget and a rusty stripe on belly. Female is rather drab, but note slightly decurved bill, spotted throat, and tail pattern.
Mussau Triller
Lalage conjuncta
A rather long-tailed and long-winged bird with a short stubby head, similar in proportions to a small cuckooshrike. Plumage distinctively clean-cut in black and white, with mostly black upperside and white underside, broad white wing panels, and a white rump barred black. Belly often tinged with chestnut. Appears dependent on primary undisturbed forest. Often quiet, but voice reportedly includes a nasal “tchow-tchow-de-weet.”
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