Black Stilt
Himantopus novaezelandiae
All black stilt with long red legs and long thin black bill, endemic to New Zealand. Juveniles have a white head, neck, and breast, with black around the eye. Breeds only on open braided rivers and connected wetlands of the Mackenzie Basin in South Canterbury and North Otago. Favors shallow waters of side streams and pools to feed on invertebrates. Some birds move to northern New Zealand harbors over winter. Juvenile Black Stilts are similar to Pied Stilts, but have shorter legs and longer bill. Hybridizes with the native pied stilt.
识别特征
Black stilts are a medium-sized (220 g) wader with extremely long pink legs, red eyes, distinctively black plumage, and a long slender black bill. Juveniles have a white breast, neck and head, with a black patch around the eyes, and black belly feathers that distinguish them from pied stilts. Black adult plumage appears in their first or second year. Black plumage may be an adaptation to "absorb heat better in the cold, windswept habitat of glacial riverbeds and lakeshores".<p>Hybrids between black and pied stilts are very variable in their plumage, but usually have black breast feathers, which pied stilts never do.
分类信息
Black stilts are one of several species in the genus Himantopus, classified along with avocets in the family Recurvirostridae. Although genetically and behaviourally distinct from pied stilts (Himantopus himantopus), they are able to successfully hybridise with them. Hybridisation and dilution of the gene pool is one reason black stilts are threatened with extinction. Black and pied stilts in New Zealand represent two colonisations of pied stilt ancestors from Australia: the first, long ago, giving rise to melanistic descendants, the second in the early 19th century.
- 学名
- Himantopus novaezelandiae
- 命名信息
- Gould, 1841
- 目
- Charadriiformes
- 科
- Recurvirostridae
- 属
- Himantopus
分布与栖息地
Although black stilts currently breed only in braided river systems in the South Island, subfossil bones show that prior to human arrival they were found in habitats as diverse as narrow bush streams in Hawkes Bay, and a wetland lake surrounded by forest in North Canterbury. In the nineteenth century they bred on riverbeds and in wetlands of the central and eastern North Island and most of the South Island except Fiordland. As late as the 1940s they were still common in South Canterbury and Central Otago, and nesting occurred in Central Otago as late as 1964. Throughout their range they have been almost entirely replaced by pied stilts, which colonised New Zealand after human settlement and now number approximately 30,000.<p>Currently black stilts breed only in the upper Waitaki River system in the Mackenzie Basin. Most black stilts will also overwinter in the Mackenzie Basin, but about 10% of the population, especially hybrids and those paired with pied stilts, migrate to North Island harbours such as Kawhia and Kaipara in January for the winter.
- 繁殖区
- AU : c South I. (New Zealand)
- 非繁殖区
- to North I. (New Zealand)
- 迁徙
- Resident species
行为
Migration pattern: Resident species.
保护状况
Population trend: rising.
- 种群趋势
- rising
照片
分布
鸟叫声
其他鸟类
Green Avadavat
Amandava formosa
Very pretty small finch-like bird with red bill, red eyes, and distinctly barred flanks. Sexes are similar, but males have brighter greens and yellows than females. Juveniles are brown above, pale with some yellow below, but have the red bill. Very rare and local. Known to occur in flocks in dry areas with open woodland, scrub, and agriculture.
Black-faced Hawk
Leucopternis melanops
Smallish chunky hawk. Identifiable by size, shape, and prominent black mask contrasting with orange cere. Generally rare. Inhabits wet forests where it hunts from the mid-level to the ground; often perches well below canopy level. Takes relatively small prey, chiefly frogs and snakes. Superficially similar to White Hawk but much smaller with orange (not blue-gray) cere; unlike White Hawk, Black-faced tends not to soar for long periods and is less frequently seen than White Hawk.
Samoan Island-Thrush
Turdus samoensis
Dark thrush with orange bill, eyering, legs, and feet. Endemic to Samoa, where found only at the highest elevations and generally not often encountered. Forages at all levels of forest, including on the forest floor. Calls include harsh chupping calls, often given in bursts.
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