An island has been waging war on rats. They think they’ve finally won
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- Rathlin Island launched a predator eradication campaign in 2023, targeting an estimated 10,000 rats plus a feral ferret population — making it one of the largest fully inhabited islands to attempt such a project.
- The RSPB completed the first feral ferret eradication on an inhabited island worldwide, killing 98 ferrets using 450 traps and announcing success in March 2025.
- The RSPB then turned to rats, placing 7,000 bait stations at 50-metre intervals across the island — including cliffs reached by professional climbers on abseil ropes — starting in September 2024.
- Project scientist Glenn Slade said most rats died within the first month; the last known rat was killed in June 2025 using thermal drones and a sniffer dog to hunt down the final holdouts.
- Rathlin residents gave permission to place bait stations on nearly every property — some inside barns, outhouses, and homes — and harbour monitors now use camera traps and laminated guides to spot any new arrivals on boats.
- Globally, nearly 1,000 islands have undergone rodent eradication with a 90% success rate for rats and 75% for mice, according to conservation biologist James Russell of the University of Auckland.
- The campaign's side effects include a rabbit population surge — ferrets were their only predator — while some non-farming residents have started keeping chickens and ducks now that rats are gone.
Why it matters: If confirmed by summer 2026, Rathlin's success would add a landmark case to the nearly 1,000 island rodent eradications attempted globally, proving that inhabited islands can be cleared using hand-placed bait stations, sniffer dogs, and thermal drones. The rabbit surge after ferrets were removed shows how eliminating one introduced predator cascades through island ecology.
