Black Stilt

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. 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.

Despite 20 years of intensive protection, the black stilt remains one of the rarest species of wading bird, and one of the most endangered birds in the world. The population may have numbered 500–1000 birds in the 1940s, but began to rapidly decline in the 1950s, and just 68 adults were counted in 1962. Intensive management began in 1981, when numbers had declined to just 23 adult birds. By 1984, there were 32 adults in the wild, rising to 52 by 1992 (with another 32 in captivity). The current wild population is estimated at 169 wild adult birds (as of May 2020), along with a captive population maintained for breeding and subsequent wild release. Annual release in the wild of these captive-bred birds, combined with predator control, have probably prevented black stilt from becoming extinct. In August 2019, 130 juvenile birds were released by the Department of Conservation onto the Godley, Cass, and Tasman rivers.