In many parts of the world, discovering a rat in your garden might barely register a second thought. However, in New Zealand, a single rat, possum, or stoat can trigger an urgent response as the country undertakes a world-leading project to eradicate all introduced predators by 2050, aiming to save its unique wildlife from further decimation.
Wellington resident Davin Hall experienced this firsthand. In March, he noticed large tunnels cutting through the compost bin at his home. Suspecting a rat, he tried to catch the pest for two weeks before calling in a team of pest-catchers who employ all possible methods to hunt down and eliminate a single rat.
"It's kind of like this idea of Ghostbusters," says James Willcocks, project director at Predator Free Wellington, which hunts down pests in the New Zealand capital. "If we get any intel from the public that might be a suspected rat, then we need to be able to deal with that immediately."
The team receives roughly five tip-offs each week, each treated with urgency. First, they determine whether a rat is actually present, says Philip Wisker, Predator Free Wellington's eradication technical officer. Occasionally, reports of rat feces in sheds turn out to belong to the wētā, an unusual endemic insect. The difference lies in the smell: wētā droppings "smell like nutmeg, spicy," while rat droppings smell "quite pooey," Wisker explains.
If a rat is confirmed, a dog detector team is dispatched to sniff out signs, followed by a capture team that sets up cameras, traps, and bait. When the rat is found—and they almost always are—it is sent for genomic sequencing to determine if it is local or has traveled into the region.
In Hall's case, the team succeeded. The intruder was a "giant rat," weighing 529 grams and measuring 495mm long, with a meaty tail and piebald coat. This Norway rat, a species that arrived in New Zealand on European ships in the 1700s, was one of the largest the Wellington team had caught.
Who ya gonna call? 0800 NO RATS
A similar response occurs if a stoat is spotted on Waiheke Island in Auckland's Hauraki Gulf, where only a few remain, and for possums in Akaroa near Christchurch and Otago Peninsula in Dunedin, where they have been eliminated. In regions where eradication efforts are successful or nearly complete, locally run predator-free projects increasingly rely on residents to call tip-offs to hotlines when they see or suspect a predator has returned.
"If we can activate those 20,000 sets of eyes and ears that are a community—or the 212,000 eyes and ears living in Wellington city—then we've got the most sensitive detection network anywhere in the world," Willcocks says.
New Zealand's only endemic mammal species are bats and marine mammals. Consequently, its birds evolved in unusual ways, with the country hosting more species of flightless birds, both living and extinct, than any other place on Earth. Isolation from land-based mammals left native birds largely defenseless against introduced predators. An estimated 25 million native birds are killed annually by rats, stoats, possums, and cats, and 50 bird species have gone extinct, according to the Department of Conservation.
Predator Free Wellington has, over 10 years, eradicated rats from the Miramar peninsula, a 15-minute drive from the city center. Now in phase two, the project aims to eliminate rats in several nearby suburbs before expanding further into the city. This success has been achieved through extensive trapping and monitoring networks, a large volunteer workforce, widespread community buy-in, and residents calling 0800 NO RATS when they spot a pest.
Since the project began in Wellington, the population of native birds on the Miramar peninsula has increased by 500%. On Waiheke, populations have risen by 99% since 2020. Despite these successes, the teams remain vigilant. Rats can breed multiple times a year, and catching a single interloper early can prevent re-establishment of a population.
Expert dog handler on the hunt
Expert dog handler Sally Bain is one of the rat-catchers. On the Miramar peninsula, she scours the coastline for signs of rats with her two highly trained dogs, Kimi and Rapu, who lead with their noses to the air. A rat was recently discovered in a trap here, prompting a search of the area. Near a small construction site, the dogs became animated. Rats regularly hide in cars, cabins, and construction materials, Bain says, and the dogs' interest could signal more rats hiding there or indicate where the dead rat originated.
Stamping out rats in a city of people is no small task. Day after day, Bain traverses Wellington's tricky hilly terrain hunting them down. When asked what drives her, Bain says: "Humans weren't the only ones who suffered when we turned up here. It's about what you save, not what you kill."
For Wellington residents like Hall, those efforts and the wider community buy-in—from building and setting traps to keeping eyes open for rats—have been "remarkably successful." He says: "We've got kererū … pooping on people's cars and sitting on powerlines, a family of kākā who live in the area and chase each other around. All these native birds have come back, and getting rid of the rats means they get to stay."
