Resolution Island. Photo: Department of Conservation / Tony Preston
The Department of Conservation is working to stamp out predators on two remote Fiordland islands this summer.
Stoat prints were detected on Chalky Island in August and two rats were found on Resolution Island in July.
Resolution Island was previously one of the country's largest without rats, and Chalky Island had been stoat-free since 1999.
DOC said eradicating pest incursions on Te Kākahu-O-Tamatea / Chalky Island and Mauīkatau / Resolution Island was a priority.
This summer, field staff would be on the islands in tight rotations with other staff providing support for logistics, planning, mapping and dog handling.
DOC Southern South Island director Aaron Fleming said the work was critical to protecting some of our most precious taonga.
"We can't afford to slow our efforts on these unique island havens that provide habitats for some of our most critically endangered species, such as kākāpō."
But eradicating the pests was proving to be a challenge.
"The response has also involved creative thinking, with the support team recently sourcing 500 metal tea strainers, which are perfect for holding peanut butter (much-loved by rats) inside the traps. The strainers stop mice nibbling the bait."
The islands are also home to some of New Zealand's precious little spotted kiwi, Te Kākahu skink, kākāpō, Fiordland skinks, geckos and giant land snails.
"Protecting these vulnerable species and their ecosystems is critical and will continue to have our highest priority," Fleming said.