NZ experts rid remote South Georgia Island of pests

Rodent detection dogs Will and Ahu and their trainer and handler Miriam Ritchie working on the South Georgia Heritage Trust's Rat Eradication Project at Discovery Point in South Georgia, Antarctica, in February.

Lying 9000km away in the southern Atlantic Ocean, the rugged and windswept island of South Georgia held scant meaning for New Zealand.

But New Zealand now means much to it, after our world-renowned island conservation expertise helped the British territory rid itself of rodents for the first time in 200 years.

And, for one Northlander and her canine companions, it has been home for a few chilly months.

The remarkable feat has left the conservation world abuzz, and offers valuable lessons for New Zealand's bold bid to be free of pest predators by the middle of this century.

Covering 108,723ha, the South Georgia Heritage Trust's seven-year project was more than eight times larger than any other rodent eradication area ever.

Brought ashore by sealing and whaling vessels from the late 18th century, rats and mice were a serious threat to wildlife, including two unique bird species.

The staged eradication technique was developed in New Zealand and many Kiwis were involved in the project: field biologists doing baseline surveys, planners helping map the entire operation — and Department of Conservation dog handler Miriam Ritchie, of Whangarei.

From summer and autumn, Ritchie and faithful Will and Ahu trekked hundreds of kilometres, searching for traces of rodents that had survived aerial poison drops.

That meant sleeping in tents and huts, rising early to eat dry and canned food, and crossing rocky, tussocked landscapes to check sites.

Perched on the edge of the Antarctic Circle, South Georgia's climate plunges to an average -4.9C over winter, but in summer can top 9C.

"It was nowhere near as cold as I was expecting," said Ritchie, whose 16 years as a DOC dog handler have taken her to our own subantarctic islands.

"We had beautiful days when I was wearing just shorts and a singlet, but we always had a pack full, including some serious wet weather gear."

The trip, which put her up close to elephant seals and emperor penguins, was a career highlight.

"The island was very grand and awesome — there were huge mountain peaks in the background, but it was mostly barren, with no trees or shrubs, and just tussock, moss, lichen and lots of scree."

Dr James Russell, a leading island conservation expert at the University of Auckland, said Kiwis continued to push boundaries in the field, having just cleared mice from Antipodes Island.

"But there was also an opportunity on South Georgia for the New Zealanders to be involved in trialling a staged approach where the eradication of rodents was broken down into smaller parts," he said. "This will likely be critical for achieving a Predator Free NZ."