Pestilent mice have been successfully wiped off subantarctic Antipodes Island following a massive poisoning operation, the Department of Conservation (DOC) says.
"This is huge news for conservation both in New Zealand and internationally," Conservation Minister Eugenie Sage said on Wednesday.
She visited the 2100-hectare islands, about 760km south of New Zealand, last month when a monitoring team was dropped off by the navy.
The team, with three rodent-detecting dogs, searched the island for almost a month and found no sign of mice.
They returned to Dunedin on Tuesday and DOC's Island Eradication Advisory Group has now declared the island officially mouse free.
The "Million Dollar Mouse" is a joint initiative between DOC and funding from the Morgan Foundation, WWF-New Zealand, Island Conservation and public supporters.
It had successfully delivered "one of the most complex island eradication projects ever undertaken", Ms Sage said.
Thirteen people spent the winter of 2016 dropping about 65 tonnes of rodent bait using two helicopters.
Project manager Stephen Horn says work started on the project in 2014, but planning began much earlier.
"The success of this project was built on the lessons and experience from many other island eradications in New Zealand and abroad," he said.
Mice were the only mammalian pest on the island.
They were most likely introduced in 1893 from a shipwreck or by one of many sealing gangs and the population was believed to have grown to about 200,000.
The rodents had since wiped out a species of weta and a large beetle and were competing with the island's unique land birds for food.
ANTIPODES ISLANDS' ASSETS:
* 21 species of breeding seabirds
* More than 150 species of insects - 17 per cent of them only found on the Antipodes
* 21 uncommon plant species
* Four unique land birds
PREVIOUS ERADICATION EFFORTS:
* 2014 - Cats and rats eradicated from Great Mercury Island in Hauraki Gulf
* 2009 - Eight mammal pests eradicated from Rangitoto Motutapu Islands
* 2001 - Rats eradicated from 11,800ha subantarctic Campbell Island
* 1993 - Rabbits and mice eradicated from Enderby and Rose Islands in the Auckland Island group
* 1992 - Small population of goats eradicated from the main Auckland Island.