A stoat manages to make its way on to a pest-free island sanctuary.

Soon after it begins prowling for its first kill, it enters a tunnel and steps on a sensor.

In real-time, the sensor scans the shape of its paw, identifies it as a stoat and fires off an alert to a ranger.

While much of New Zealand's bold bid to be rid of pests is uncertain, cutting-edge technology like this is expected to play a crucial part.

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Dubbed the Paws (Print Acquisition for Wildlife Surveillance) pest identification sensor pad, the device is designed to detect and identify pests in places like islands or mainland sanctuaries where possums, rats and stoats have already been cleared out.

The Department of Conservation (DoC) has just signed a contract with Lincoln Agritech to develop the technology with collaborators Boffa Miskell and Red Fern Solutions, as part of a $2.8 million funding roll-out for new research.

Trying to detect stoats and weasels has been a costly and time-consuming job for conservationists, who have often had to rely on tunnels with ink pads and cards inside them.

Analysing the cards for paw prints wasn't always straightforward, as the traces of a moving animal with muddy paws could be indecipherable.

The new technology, however, could be left in remote locations with little human intervention, saving park rangers the need to keep checking the pads.

Trials in Christchurch's Port Hills and forests in the West Coast had found it to be highly effective at detecting stoats, ferrets, possums, cats, rats and mice.

Lincoln Agritech principal scientist Clive Marsh said the team was perfecting the design this year, ahead of further small-scale field trials next year and larger ones in 2020.

The Paws system can be left in remote locations with little human intervention, saving park rangers the need to keep checking the pads. Photo / Helen Blackie, Boffa Miskell
The Paws system can be left in remote locations with little human intervention, saving park rangers the need to keep checking the pads. Photo / Helen Blackie, Boffa Miskell

"The intention is for pre-production units to be tested by DoC in early 2021 prior to a commercial launch."

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The trials are being led by Dr Helen Blackie of Boffa Miskell, who was involved in the technology's inception after seeing the need for better surveillance and reporting.

DoC's Auckland operations manager Andrew Baucke expected the new pads would cut down the workload for rangers, along with the response time to any reinvasions.

"A lot of labour goes into regularly checking traps and tracking tunnels on islands to detect pest reinvasion," he said.

"Some of our pest-free islands are not visited as often as we would like."

Pests such as stoats, rats and possums are estimated to each year kill around 25 million native birds, at a time when 81 per cent of native bird species are either threatened or at risk of extinction.

New Zealand is now working toward a goal of clearing stoats, rats and possums from 26 million hectares of mainland, along with all offshore islands, by 2050.