Critically Endangered waders released in New Zealand

Some 143 Black Stilts have been released at a site in New Zealand in an effort to boost the population of the Critically Endangered species.

The birds were released on 10 August at locations in Mackenzie Basin, an important wintering site for Black Stilt (known as Kakī in Māori), at the Godley and Tasman Rivers. Among them were several juveniles born to a captive female nicknamed 'Māwhero'.

Department of Conservation (DOC) Kakī Recovery Programme Wild lead Claudia Mischler said the species' wild adult population is up to about 156 adult birds (not including those just released), and was generally trending up over time, though it does fluctuate.

Black Stilts being released in the Tasman Valley on 10 August (Liz Brown / DOC).

"The Kakī have had a long journey since the 1980s when they were down to 23 adults – they've come a long way now,'' Mischler said.

Mischler said staff will provide the newly released stilts with supplementary feeding for the next few weeks to help them settle into their new environment while they learn to fend for themselves. She said the breeding programme was successful and work continued to improve the birds' survival rates in the wild.

Captive rearing for wild release takes place at DOC's Twizel facility and The Isaac Conservation and Wildlife Trust in Christchurch.

One well-known bird held in captivity is the aforementioned Māwhero. She comes from a lineage under-represented in the wild, which means she is important for improving the genetic diversity of the species.

She was offered several suitors and originally partnered with a male called 'Wiremu'. The pair had a very successful first breeding season but then Wiremu died suddenly due to cancer in February 2022, leaving Māwhero to raise the chicks on her own.

In November, a wild male Black Stilt began hanging around DOC's captive-breeding aviaries at Twizel. He was particularly interested in Māwhero so staff opened the door and let the male in, and they soon formed a pair. They were very successful this breeding season, raising several clutches of chicks.

For more information about kakī and the recovery programme visit doc.govt.nz/kaki.