Northland's Motukawanui Island may be a species saver: Researchers

New Zealand through the lens: Northland's Matauri Bay. Photo / Richard Robinson

Motukawanui, the largest of the Cavalli Islands, off Matauri Bay, is one of 107 islands around the world that have been identified by a major international collaboration of scientists, researchers and conservationists as offering the best chance to save some of the world's most threatened species.

Four other New Zealand islands — the sub-antarctic Auckland, Slipper (Coromandel), Kawau and Great Barrier islands (Hauraki Gulf) are also on the list.

Forty institutions, including universities and major conservation organisations such as Birdlife International and the International Union for Conservation of Nature (IUCN), contributed to the assessment of islands, the list appearing last week in the journal PLOS One.

"We already know islands are a vital conservation opportunity, but this study gives us the bigger picture, a list of locations where the most progress could be made," said Associate Professor James Russell, from the University of Auckland, who contributed to the research.

"One of the study's most important aspects is that it not only assesses the feasibility of eradicating predators on these islands, but assesses how feasible this work would be from a political and socio-economic point of view."

Restoring islands by eradicating damaging, non-native invasive mammals such as rats, cats, goats and pigs had repeatedly proven to achieve results and make a major contribution towards stemming the global extinction crisis, while initiating restoration projects on 107 islands with a total land area of 1623 square kilometres could save 151 populations of 80 threatened species.

The Cavalli Islands seen from Taronui Bay. Photo / Bay Report

Currently more than 1200 invasive mammal eradication projects on islands globally had had an average success rate of 85 per cent.

Dr Russell said New Zealand was one of the most experienced countries in the world in terms of island pest eradication, and had lent expertise to a wide range of island projects, from Mexico to the Pacific.

"New Zealand has been offering support to other countries for some time, and is seen as a global leader in this area, with our own ambitious targets such as pest-free Auckland Island and Predator Free New Zealand," he said.

The researchers used biological and geographic data compiled for 1279 islands with 2823 populations of 1184 bird, reptile, mammal and amphibian species listed by the IUCN Red List of Threatened Species as critically endangered or endangered.

The study identified 107 islands where predator eradication could begin by 2020, and a further 62 where work could start by 2030, to benefit 9.4 per cent of the world's threatened island species in total.

Dr Nick Holmes, lead author of the study and director of science at the international conservation group Island Conservation, said islands currently supported 36 per cent of bird, mammal, amphibian and reptile species that were classified by the IUCN as critically endangered.