A Kiwi start-up has attracted international attention for its role in the world's first operation using drones to make an island rat-free.

The effort, under way this month in Ecuador's famous Galápagos National Park, is prompting questions over the part drones might play in New Zealand's war on pest predators.

North Seymour Island – comparable in size to the Hauraki Gulf's Motuihe Island – and nearby Mosquera Islet are important nesting sites for species such as frigate birds and swallow-tailed gulls, the only nocturnal gull on the planet.

When it was recently discovered they were infested with black and brown rats, an eradication programme backed by global group Island Conservation quickly kicked into gear.

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This month, more than 30 rangers spread specially-made rodenticide across half of North Seymour Island.

The other half was being covered in a pilot project involving New Zealand start-up Environment and Conservation Technologies, which was using drones and hoppers with applicators designed in 3D printers.

Although the remaining rats were expected to be cleared by the end of this month, it would likely take another two years before the islands could be officially declared rodent-free.

Island Conservation's Karl Campbell said, previously, such an operation would have required helicopters, specialised pilots and spray buckets.

"The use of drones is more precise; it also increases feasibility, and reduces eradication costs of invasive rodents in small and mid-size islands worldwide."

The mission had already garnered significant interest in New Zealand and elsewhere around the world, with news coverage by Nature, Wired, Popular Mechanics and The Independent in the UK.

Environment and Conservation Technologies' Morwenna Berry said using the drones was much more time-efficient and safer than having a ground team conduct the same work.

"We are very happy with our results so far and have ambitions and opportunities to continue to replicate our success so far both in New Zealand and worldwide," Berry said.

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Back in New Zealand, researchers have just begun a trial using drones in a range of habitats and environments.

Associate Professor Craig Morley, of Toi Ohomai Institute of Technology in the Bay of Plenty, said drones had the advantage of offering targeted control in areas that weren't being covered, or where people couldn't access.

"Dropping toxins using a swath bucket has been a bone of contention for many, and our goal is to improve precision and accuracy by being targeted," he said.

"More importantly, we wish to trial an alternative to 1080 because of the controversy surrounded by this toxin."

One of the drones over North Seymour Island. Photo / DGNP
One of the drones over North Seymour Island. Photo / DGNP

At this stage, the project, which also involved Whakatane's Ake Innovation and Auckland's X-Craft, was using non-lethal methods so the approach could be properly tested.

"Once we have ironed out all the issues, and that won't be far off, then we will apply to the EPA to apply to use drones in real control operations."

The Department of Conservation was also watching the use of drones with interest.

"Currently, payloads are limited so the most potential is for small, remote Pacific Islands which are far away from the nearest helicopter," DoC technical advisor Keith Broome said.

There might also applications for drones over parts of islands that couldn't be reached on foot, he said.

"As the technology matures, no doubt other applications will arise."

About half of New Zealand's 220 large islands had already been cleared of pest predators.

But University of Auckland conservation biologist Dr James Russell said it was unlikely drones would ever replace helicopters for those large-scale 1080 drops across mainland areas.

"Drones sound cheaper, but in the end, it's fairly expensive: you need to maintain them and you need five times as many of them flying around the same area," he said.

"But the Galápagos operation is another great example of how New Zealand is leading the world in this area.

"It's like what [naturalist and broadcaster] Sir David Attenborough said at Davos this month: 'the knees of rats shake when New Zealand is near'."