Taonga species fighting back from extinction

Kakī / black stilts numbered just 23 birds in 1981, but are now recovering well. Photo / Liz Brown, DoC

In 1981 the kakī, or black stilt, numbered just 23 birds. The native wading bird was on the brink of extinction.

Last week, nearly 160 birds bred in captivity were released into the Mackenzie Basin to join the 170 or so birds in the wild as part of a recovery programme that is turning around the fate of this taonga species.

Dean Nelson, senior biodiversity ranger for the Department of Conservation (DoC) in Twizel, says 80 birds were released at Lake Tekapo and a further 78 into the Tasman Valley in early August.

Sub-adult kakī / black stilts are released into Te Manahuna / Mackenzie Basin at Tasman Valley. Photo / Liz Brown, DoC

“Staff will provide the newly released sub-adult kakī with supplementary feeding for up to six weeks to help them settle into their new environment while they are learning to fend for themselves,” Nelson said.

“We’re also retaining eight young kakī in captivity and it’s hoped they will become future captive breeders. They have been selected to retain maximum genetic diversity in the captive population.”

Kakī are found in braided riverbeds, side streams, swamps, lake margins and irrigated paddocks and can migrate to coastal areas in winter.

They can form lifelong pairs, which is an issue if they can’t find another black stilt with which to mate, so have been known to mate with the pied stilt (poaka).

It's been a positive breeding season with 41 pairs producing eggs, up from 17 ten years ago. Photo / Liz Brown, DOC

This hybridisation of species is a threat to their survival along with the usual suspects of predation, habitat loss and human disturbance, but active, intensive management is making headway.

Nelson said the past season saw the highest recorded number of breeding pairs in the wild with 41 pairs producing eggs. Ten years ago, that number was just 17 pairs.

“It’s been a positive breeding season for kakī, but they are still doing it tough in the wild as they are vulnerable to introduced predators,” Nelson said. “On average, about 30% of released birds survive to adulthood.”

Extensive trapping takes place across the Mackenzie Basin, including through the Te Manahuna Aoraki Project and Project River Recovery programmes, with vital support from local landowners.

The recovery programme’s next goal is research to better understand the causes of mortality and develop methods to increase the survival rate.