Stilt (Black) Himantopus novaezelandiae
Species: H. novaezelandiae
Binomial name: Himantopus novaezelandiae
Common names: Black stilt, kakī
Himantopus novaezelandiae, is found only in New Zealand, and is the world's rarest and one of the most endangered wading bird: less than 100 adults survive in the wild. Black stilt adults are a medium-sized wader (40 cm., 220g.). They are entirely black, and have very long, pinkish red legs, a long thin black bill and red eyes. 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 is thought to be an adaptation to absorb heat better in the cold, windswept habitat of glacial riverbeds and lakeshores.
Currently black stilts breed only in the upper Waitaki River system in the Mackenzie Basin. Most black stilts will also over winter 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.
Black stilts breed at 2 (more usually 3) years of age. They nest as solitary pairs, not in a protective colony like pied stilts. Both birds collaborate on building a nest in July or August on stable islands or banks in a shingle riverbed; pairs tend to nest in the same site each year. Three to five eggs are laid from September to December, peaking in October, and are incubated for roughly 25 days. Chicks take six to eight weeks to fledge, and remain with their parents for a further six to eight months.
Black stiltsare threatened by introduced feral cats and ferrets, as well as habitat degradation from hydroelectric dams, agriculture, and invasive weeds. Predation from mammalian invasive species poses the greatest threat to the survival of the species. In the 19th century, mustelids such as stoats, ferrets and weasels, as well as cats, were released into the Mackenzie Country to try to control the spread of rabbits. Black stilts are very vulnerable to these predators: they nest on the banks of streams and rivers, rather than islands; their nesting season begins in late winter, a time when rabbit numbers are low; and they currently nest as solitary pairs, so lose the protection of a colony (although they formed colonies in the past when numbers were higher). Intensive trapping and electric fences are used around black stilt breeding sites to control predators. In the 1980s,
Black stilts numbers plummeted to 23 adult birds. However, the captive management programme at Twizel is making a real difference, as this video reveals.
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