Browse Island is seventeen hectares of coral and scrub, one hundred and eighty kilometers off the Kimberley coast, and last October it received seven hundred kilograms of bright green pellets dropped from a six-rotor drone. The pellets were rodenticide. The target was every single house mouse on the island.
The operation, completed in October 2025, was the world's first attempt to eradicate invasive house mice from an island using drone-delivered bait. The Western Australia Department of Biodiversity, Conservation and Attractions (DBCA) ran it in partnership with Monash University and New Zealand drone specialists Envico Technologies. Researchers will return in April to find out whether it worked.
House mice arrived on Browse — a low coral cay in the Timor Sea — sometime in the late 1800s, likely carried by guano miners or foreign fishers, according to the Australian Broadcasting Corporation. They found an island that had once hosted tens of thousands of seabirds: boobies, frigatebirds, terns, tropicbirds. The mice ate what mice eat: eggs, chicks, whatever they could reach. Over a century, the breeding colonies collapsed.
"We know Browse Island was once thriving with seabirds," Dr. Donal Smith, a researcher with Monash University's ecology team, told The Kimberley Echo. "What we'd love to see here is the island return to that incredibly beautiful state. There's precedent for these kinds of incredible recoveries."
Getting there required solving a problem that ground-based baiting and helicopters had failed to solve. Browse Island is dense with low vegetation — the kind that breaks up helicopter downwash and makes it impossible to walk bait lines across every square meter. Humid conditions and soaring daytime temperatures ruled out extended human presence for hand-baiting. The island sits behind a reef and surf zone; accessing it by boat takes two days from the mainland, ABC reported.
Bruce Greatwich, DBCA's Kimberley conservation coordinator, described what he saw when the drone arrived: "We were all blown away to actually see it in action and see the pellets flying out," he told ABC.
The hexacopter — custom-built in New Zealand by Envico Technologies — carried approximately twenty kilograms of bait per flight. Envico pre-programmed the flight mission using accurate three-dimensional models of the island, navigating around cliff lines and varying topography without manual piloting for each pass. The aircraft used specialist spreaders capable of multiple dispersal patterns: full swath, directional swath, trickle, and cluster, according to Dronelife. At Envico's standard application rate of roughly twenty kilograms per load, the seven hundred kilograms of bait required at least thirty-five flights per round.
That specificity matters enormously in island eradication. "If you have gaps in your baiting application, then you're at risk of failing, because you really need to get literally every single individual of the rodent that lives out there," Greatwich told ABC. "If you do not get one little square metre, then the mice can just hang out in that area, and they might have enough food within that area, and then start breeding again," Mike Jensen of Envico Technologies told Dronelife.
The team ran two rounds of baiting, two weeks apart. Researchers stayed on the island after the first drop to monitor bait uptake — checking whether the mice were actually eating the pellets. A second pass handled whatever survived.
Envico is not new to this work. The company conducted the world's first island vertebrate pest eradication by drone in January 2019, dropping three thousand kilograms of bait across Seymour Norte in the Galapagos Islands — an island of 184 hectares. Since then it has worked on eradication projects in New Zealand and internationally, building drones specifically designed for aerial baiting rather than retrofitting consumer aircraft.
Associate Professor Rohan Clarke of Monash University, who led the project, said the house-mouse-specific targeting made this a different kind of world first. "Rodents, generally on islands, are recognised as one of the most significant threats to biodiversity globally," he told The Kimberley Echo. "This is the first time that an eradication has been attempted for house mice anywhere in the world that's using drones."
Whether it succeeded won't be known until researchers return in April. The assessment will be straightforward in principle: no mice, no problem. In practice, confirming absence on a remote island after a single breeding season requires patience and careful monitoring.
The outcome will matter beyond Browse. Islands worldwide host invasive rodents that have devastated native bird populations — one of the leading causes of avian extinction. Conservation teams have used helicopters and hand-baiting for decades. Drone technology offers something new: the precision to cover every square meter of terrain that is too thick, too remote, or too hot for people to reach on foot, without the cost and logistical footprint of a helicopter operation.
If Browse succeeds, it won't just be a win for the seabirds that once nested there in their thousands. It will be a data point — a real, ground-truthed result — for every conservation team weighing whether to trust a drone with an eradication that took a century of effort to set up.
That answer arrives in April.
