The Black Stilt or Kak? (M?ori), Himantopus novaezelandiae, is a large wader in the avocet and stilt family Recurvirostridae. The species is endemic to New Zealand. Adults are 40 cm long. They have very long red legs, a long thin black bill and black plumage. Juveniles have a white breast, neck and head, with a black patch around the eyes.
Ecology and conservation
Despite of 20 years of intensive protection, this species remains the rarest wading bird in the world. In 1994 there was a population of 119 birds and the current population is estimated at 22 adult birds. There is a captive population of some 25 adults, annual release in the wild of captive-bred birds and predator control has probably prevented it from becoming extinct in the wild. During the breeding season it is restricted to the upper Waitaki Valley in the South Island. Small numbers overwinter in the North Island.
They breed at the 2-3 years of age. They are one of the world's most endangered birds. Drainage and hydroelectric development has in the past disturbed their braided river bed habitat. Predation from mammalian invasive species, most notably mustelids such as stoats presently poses a serious threat to the species survival. The third major threat to this species is hybridization with the local and more numerous Pied Stilt H. himantopus.
Effect of hydroelectric power development
Since the Black Stilt nests on the braided rivers beds of the South Island, it is threatened by changes in river flows as a result of new hydro dams and changes in flow regimes for existing dams.
The Upper Waitaki Power Development posed a threat to the black silt habitat and a programme was set up to lessen the threat to the stilt. Black stilt population on the river beds varies with the river level. Changes in the level of Lake Benmore, which caused corresponding changes in the deltas of the incoming rivers, affected the local population of Black Stilts.