Source: Radio New Zealand
A pair of pukunui. DOC
A controversial 1080 drop on Stewart Island has led to a 52 percent population boost for threatened Southern New Zealand dotterel/pukunui.
The birds, which only breed on Stewart Island / Rakiura, have been teetering on the brink of extinction, with 40 to 50 adult birds being killed by feral cats each year.
The population has now grown from 105 to 160, the largest increase since recovery efforts began 32 years ago.
The goal is to increase the population to 300 by 2035.
Department of Conservation Rakiura Operations Manager Jennifer Ross said the aerial drop of 1080 completed by DOC and Zero Invasive Predators made the difference.
“We managed to reduce feral cats to very low levels in the operational area. This protected adult birds while they nested and raised their chicks on the mountain tops.”
Ninety one out of 97 previously known adult birds survived along with 56 newly banded juveniles, one new adult, and five unbanded birds. As in previous years, 5 percent was added to account for birds that weren’t present during the count.
Year round trapping had failed to control feral cat numbers. DOC rangers have previously told RNZ an abundant rat population on the island meant rats stole trap baits before feral cats came across them.
The strategy to use 1080 was based on a “secondary kill” approach. Cats don’t eat the cereal 1080 baits, but rats do, and cats eat rats.
The 1080 operation, completed in August 2025 covered 40,000 hectares and included half the known pukunui breeding areas on the island, as well as surrounding forest, ahead of the breeding season.
No further aerial predator control operation is planned on Rakiura this year, and feral cats will continue to be closely monitored.
“The big question is how long it will take feral cats to reinvade pukunui breeding sites in the operational area,” Ross said.
A feral cat with a rat DOC / Department of Conservation
A member of the Ngāi Tahu leadership group involved in Predator Free Rakiura Dean Whaanga said the birds are far from safe.
Trail cameras have detected feral cats at the edges of the operational area, and they are present at breeding sites elsewhere on the island.
“It’s critical we continue to take action, not just for pukunui, but to uplift the mauri of Rakiura and enable other taonga species like kākāpō and tīeke to safely return,” he said.
Protest signs on Stewart Island RNZ / Mark Papalii
Opinions on the remote island were split about the 1080 drop, with some opposed to the poison.
There’s been subsequent concern after it was discovered white-tail deer on the island are more vulnerable to the toxin than expected.
White-tail deer were not a target species for poisoning, although there is footage of the deer eating dotterel eggs out of nests.
Bait pellets containing deer repellent were used in hunting blocks, while standard 1080 bait pellets were used elsewhere in the operational area. Trail cameras monitored deer before, during and after the predator control operation.
On average, there was a 75 percent reduction in deer detections by cameras in the deer repellent area, and a 97 percent reduction where standard 1080 bait pellets were used after the 1080 was dropped. Additionally, hunters found four dead deer after the operation.
A trial of the deer repellent before the drop took place was conducted, but the results were inconclusive as other pests ate the baits before deer encountered them.
When the trail camera results were released after the 1080 drop, president of the Rakiura Whitetail Trust, Adam Fairmaid said the trust wanted a viable population of deer on the island and DOC had assured the trust a solution would be found.
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– Published by EveningReport.nz and AsiaPacificReport.nz, see: MIL OSI in partnership with Radio New Zealand