Pest control reverses ‘downward slide to extinction’ for kiwi

By RNZ

A remote Fiordland kiwi population feared to be sliding towards extinction is turning the tide and increasing in numbers for the first time in their conservation history.

The Fiordland tokoeka (southern brown kiwi) population at Shy Lake is growing about 2 per cent a year.

The Department of Conservation said chick survival in the area was zero before aerial predator control — 1080 bait — was used, aimed at mostly stoats.

Tokoeka project lead Chris Dodd said the increase was a significant win for the species and was thanks to aerial predator control.

“It means not only are chicks surviving long enough to replace the adults, enough are making it to adulthood to officially grow the population,” Dodd said.

A ranger changes a previous season's tokoeka chick's radio transmitter at Shy Lake. Photo / DoC

“Adult kiwi are typically more resilient to stoat attacks, but natural mortality — old age, misadventure, disease — means the population was declining by about 2 per cent per year with no chicks surviving to replace the adults.”

DoC has been monitoring the Sky Lake population since 2017.

Dodd said it represented what was happening to the wider Wet Jacket peninsula.

“Without action, the Shy Lake kiwi population was on a downward slide to extinction.”

The first 1080 operation started in the winter of 2020, and a second took place last winter with none of this season’s chicks dying from stoats so far.

One of the chicks recently reached the stoat-safe weight of 1kg months earlier than expected.

DoC expected that was probably due to the availability of food that wasn’t being eaten by predators anymore.

“Fiordland tokoeka live in harsh, rugged terrain. Even without the threat of predation, it can be an uphill battle surviving through to adulthood. We can’t control the environment, but we can do something about the stoats and give these chicks a better chance,” he said.

The efforts to save the species have been captured in a three-part miniseries — The Fiordland Kiwi Diaries — that was released last year.

While it was a positive start, the fight to protect the Fiordland tokoeka continues because only a quarter of its habitat received any predator control, and the Wet Jacket Peninsula represented less than 5 per cent of its total habitat.

The Seaforth-Grebe block east of the Wet Jacket Peninsula will be the next area to be targeted by predator control this winter.

– RNZ