Drones for pest control

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A ghostly grey image appears on the laptop screen. “You see these deer?” asks Jordan Munn, pointing at a corner off the screen where a pair of animals are highlighted in bright white. 

“I have directed a hunter to these deer. He's actually just shot this one, this deer to the right, and it's about to fall over,” he says.  

The brilliant silhouette of the first deer tumbles to the ground, the second follows a few moments afterwards.  

Hunting with heat 

Jordan is professional hunter and owns a company called Trap and Trigger based in Upper Hutt. The company has contracts with several regional councils for eliminating everything from deer to wallabies to wilding pines 

And Jordan says there’s a new technology revolutionising the industry – small commercially available UAVs (unmanned aerial vehicles), or as they are more often called: drones.  

“We're becoming more and more reliant on them,” Jordan says. “It's amazing how the pest control industry has reshaped in the last decade. Ten years ago, [drones were] basically non-existent.” 

When mounted on a drone, the thermal vision of an infrared camera makes warm-blooded deer, wallabies and other mammalian pest species stick out like a sore thumb – even when the animal is mostly obscured by scrub.  

A decade ago, Jordan says, even a thermal imaging camera or scope was beyond the budget of most commercial hunters. But costs have come down radically over the past decades, and they are still dropping.  

“Within a few years, every contractor will have a thermal handheld camera and a thermal scope and a thermal drone. And if you don't have one of those or all of those, you're lagging behind,” Jordan says. 

It all seems very science fiction, and Jordan speculates it could be possible to use drone technology to remove the hunter from the equation entirely.  

“We haven’t yet got guns on them,” Jordan says. “But if we could legally use a firearm from a drone safely.... It would work. It would work very well. But there will be a few issues, social issues and legal issues to get to that point." 

While weaponised drones aren’t likely to arrive in New Zealand any time soon, Otago Regional Council is already experimenting with fully autonomous drones for a different type of pest. 

Tree terminators

Gavin Udy is the project delivery specialist for the Environmental Implementation Team at Otago Regional Council. And one of his main projects is a trial to see if drones can hunt down and eradicate wilding pines, basically by themselves.  

“A drone goes out and it searches a predetermined area, and it flies through this area searching, for wilding conifers.” 

Wilding conifers are introduced, invasive pines that risk smothering large parts of the South Island’s high country landscapes. 

Gavin says the drone uses artificial intelligence (AI) image detection trained on images of various kinds of trees – allowing it to identify wilding conifers all by itself. And it doesn’t end there. 

"It can then take a GPS location of where that tree is. It can take a photograph of that tree and it can estimate the size of that tree in terms of its height and also its diameter of all of its foliage. After it does its survey flight, all of that information is collated.” 

At this point, the data is checked by a human operator, then the data is passed along to a second, larger drone loaded with herbicide.  

"And that drone is then able to go out, following a flight path that has been analysed as being the most efficient flight path, and it's able to go along and spray all those trees, spraying the right amount of herbicide onto that tree – just enough to kill it.” 

Gavin says they won’t know how effective this autonomous pine eradication trial has been until the end of 2024, but some scientists are extremely enthusiastic about the potential of the technology for pest control. 

Flying tractors 

Dr Justin Nairn is the team lead for Plant Protection Physics and Chemistry at the Crown research agency Scion. And his hopes for drones in pest control are sky high.  

“They can fly lower and slower to the target," Justin explains. “[A drone is] far more precise, with how accurately it can deliver the spray compared to a helicopter or a fixed wing aircraft, for instance, which generally have to travel a lot faster, and further away from that target.” 

Justin is currently running experiments to see how drones could be used to spread insecticides and other control agents in response to a biosecurity breach. He says the tech is particularly promising for urban areas. 

“We have sprayed over entire cities in the past, but it's always come with a lot of resistance… People are not going to trust it," he says.   

Drones on the other hand can be far more precise, targeting particular areas, or even particular types of plants where they suspect invasive pests are hiding. 

And Justin says soon, emerging high-tech batteries could see drones increasingly compete with helicopters and other aircraft. 

“We're forecasting that those will basically take away a lot of that flight time limitation. And then as you begin to scale it, you're basically going to have a flying tractor. You can put whatever equipment and tools and whatever you want on it,” Justin explains. 

“I think it's going to revolutionise the primary industries, to be honest.” 

Listen to the audio to learn more about how drones are being used for pest control in Aotearoa right now.  

Learn more 

• Listen to RNZ’s podcast Deer Wars to hear the wild story of the 50-year struggle to control New Zealand’s red deer population.  

• Pest control isn’t the only use of drones in science – they've also been used to count penguins on remote islands, help kākāpō recovery by flying sperm, to ID whales and check how chubby they are, monitor grape vines, and find tiny birds in a big ole forest.