High-tech tool could boost bid to make New Zealand predator-free

A mouse, fitted with a transmitter, that was tracked as part of a study on an island off the coast of Mexico. Photo / GECI

Cutting-edge software trialled by University of Auckland researchers could help achieve New Zealand's bold goal of becoming predator-free by 2050.

Joint research between the university's Department of Statistics and School of Biological Sciences has led to a new online tool that can quickly confirm whether pests have been successfully eradicated from an area.

Users enter basic parameters about pest populations, such as how far individuals can move and how likely they are to be detected and what level of effort will be put in to monitoring.

The software then calculates how likely it is pests have been eradicated from the area if none are detected.

Further, it allows users to simulate different monitoring scenarios which would boost the confidence in confirming eradication success, such as giving a probability of over 95 per cent.

By playing with real data from Isla Desertora off the coast of Mexico, the research team calculated the probability that all the mice eradicated on the island in 2011 really were dead.

Study co-author Dr James Russell, who also worked with Landcare Research and Mexico's Grupo de Ecologia y Conservacion de Islas (GECI) on the project, said the resource would be valuable to conservationists.

"With new bold visions to eradicate introduced predators from the entirety of New Zealand by 2050, and all of its offshore islands along the way, managers need cutting-edge scientific tools to enable them to confirm eradication as quickly as possible so they can move on to the next project."

GECI researcher Dr Araceli Samaniego-Herrera, who originally developed the tool as part of her PhD at the University of Auckland, was also encouraged by the results.

"The original idea came from Landcare scientists, so GECI teamed up with them to develop a tool to speed-up our island eradication projects in Mexico," she said.

"We've been testing novel management approaches so we needed to know if we were on the right track sooner rather than later.

"After eight successful projects, I'm very happy with the software."

The Government's new 2050 plan has four goals with a 2025 deadline: to sweep pests from another million hectares of land, to develop a scientific breakthrough that could exterminate at least one mammalian predator, to demonstrate areas of more than 20,000ha could be predator-free without the use of fences, and to complete removal of all introduced predators from offshore island nature reserves.

Non-native pests kill around 25 million native birds every year and although they have been cleared from nearly half of the country's small islands in a programme that began 50 years ago, a pest-free mainland - an area of 26 million ha - has remained a trickier question.

When the Herald investigated the issue in 2013, it was noted the cost of clearing possums and wallabies out from Rangitoto/Motutapu had cost $3.5 million - by extrapolation, the sum for the rest of the country had been estimated at $24.6 billion.

But scientists say big advances in technology would lower the cost and help meet the goal.

The study is published today in the British Journal of Applied Ecology.