Kiwis take front line in global war against invasive species

New Zealand is home to one of the highest proportions of threatened species in the world. Desperate to save its beloved wildlife, the archipelago nation is seizing on a drastic and controversial strategy: kill all the predators.

Mark Baker/AP
Two shag chicks sit on a nest with their mother at Zealandia in Wellington, New Zealand, on March 22. People across New Zealand are embracing an environmental goal so ambitious it’s been compared to putting a man on the moon: ridding the entire nation of every last stoat, possum, and rat.

New Zealanders are deeply connected to their land, and the menagerie of peculiar critters that have evolved on the nation's hundreds of islands. But in recent years, Kiwis, as residents call themselves, have watched with dismay as their country has become ground zero of Earth’s extinction crisis. With fierce determination, however, they have also become the tip of the spear in fighting it.

Home to one of the highest proportions of threatened species in the world, New Zealand's wildlife is in a state of crisis. The first global analysis of established alien species, published Monday, ranked New Zealand, along with Hawaii and Indonesia, as one of the globe's three hotspot regions for invasive species. With nearly a third of the country’s endemic species at risk, including its talismanic kiwi bird, the nation has taken on a seemingly insurmountable challenge: total elimination of three invasive predators from its two main islands by the year 2050. The endeavor has earned the moniker “New Zealand’s Apollo program.”

Non-native predators are some of the biggest threats to New Zealand wildlife. Scientists estimate that invasive stoats, rats, and possums kill 25 million native birds in the country every year. That threat looms large for New Zealanders, who view nature as “almost like our church,” says Nicola Toki, Threatened Species Ambassador for the New Zealand Department of Conservation (DOC).

“Our nature is who we are, and we can’t describe ourselves as Kiwis to the rest of the world if we don’t have any left,” she says.

The country is already a world leader in invasive species management, but an eradication on the scale of the Predator-Free New Zealand 2050 (PFNZ) initiative would be unprecedented. The science to achieve it doesn’t exist yet, and it would likely unearth social and logistical challenges that invasive species managers have never seen or even contemplated before.

Yet the potential benefits, for New Zealand and the entire planet, could be immense. The planet is currently experiencing what many scientists believe to be the sixth mass extinction event in the past 500 million years, with about a quarter of all the planet’s known species on track to go extinct by 2050. If PFNZ is successful, experts say, it could unlock new techniques and technologies to prevent tens of thousands of species around the world from being wiped out.

And if anyone can achieve it, the Kiwis can, says Daniel Simberloff, an ecologist at the University of Tennessee, Knoxville and an expert in invasive species.

“Of all the nations in the world, they have been certainly the most aggressive in dealing with this problem,” he adds, especially on New Zealand’s smaller islands. “But the idea of eradicating introduced predators from [the main islands], that’s a quantum leap.”

Nick Perry/AP
Workers assemble resetting rat traps at the Goodnature factory in Wellington, New Zealand.

The world is watching

The rest of the world is eagerly watching New Zealand and the PFNZ initiative.

Simply perfecting eradications on uninhabited islands – which New Zealand is already close to doing – would alone have a huge impact on global conservation, says Heath Packard, the director of communications at Island Conservation, a Santa Cruz, Calif.-based nonprofit dedicated to preventing extinctions by removing invasive species from islands around the world.

Island Conservation is currently struggling with its own challenges of carrying out an eradication on an inhabited island. The organization has been working for seven years to plan and fundraise for a rat eradication on Floreana Island in the Galápagos.

“We are continually reaching more complex projects,” Mr. Packard adds. “The ambitious vision that New Zealand has could be a major stepping stone for us to be considering places that are much bigger and grander in scale.”

Forty percent of endangered species worldwide live on, or rely on, islands, and invasive species are the leading cause of extinctions on islands. Since 1500, 80 percent of all recorded extinctions have been on islands.

But Floreana illustrates the scale of New Zealand’s challenge – and its potential benefits. The island is only 67 square miles, with a permanent population of 140 people, and Island Conservation’s eradication project would likely cost at least $7 million. New Zealand’s largest offshore island, Rakiura Island, by comparison, is 10 times as large, with almost three times as many people.

“The prospect of what New Zealand is trying to achieve” lends hope, says Packard, that “there may be tools and techniques in place to consider reversing the extinction trajectory in a place like Hawaii,” which is home to about a quarter of all endangered species in the United States.

How small mammals became such a big problem 

For about 80 million uninterrupted years, native wildlife evolved on the islands of New Zealand without the threat of ground-based predators. The Maori didn’t settle the islands until about 1350, while European explorers didn’t arrive until 1769. With the arrival of humans, other invasive mammals weren’t far behind.

And for animals that evolved to only look to the sky for threats, the results have been predictably devastating.

For native wildlife, the “best thing to do in face of avian predators is to be camouflaged and to freeze,” says the DOC’s Dr. Toki. “If you camouflage and freeze and a ferret’s chasing you, you don’t stand chance because those things use smell.”

Rats arrived in the late 1700s, while New Zealanders brought possums in the 1830s to establish a fur trade that still exists today. Stoats were introduced in the 1880s to help control rabbits and hares. Since the mid-1800s there have been 20 bird extinctions in the country. 

New Zealanders began to take invasive predators seriously in the 1970s, and the country since has become the world’s leading expert on the issue. Invasive predators have been eradicated on 117 of the country’s offshore islands, and the country develops traps and bait systems used around the world. That success has been replicated globally, with about 1,000 offshore islands now cleared of invasive predators. 

“We’re good at killing small furry animals,” says Toki. “If you look at any pest eradication program around the world, it will generally have a Kiwi scientist running it or a Kiwi helicopter pilot [helping] it.” 

The most stubborn invasive species 

Eradicating invasive predators from small uninhabited islands is one thing, but Phil Cowan – an ecologist at Landcare Research, a government-funded research organization – laughs off the suggestion that PFNZ will involve simply scaling up that approach.

“Almost all the eradications of pests from islands, both in New Zealand and globally, have been done on uninhabited islands,” he says, “so trying to do operations like this in areas where people are living is going to require a whole lot of discussion with people who live in these areas to work out what will be acceptable and what will not.” 

Ironically, the species in New Zealand that conservationists there expect to be toughest to deal with isn’t rats, possums, or stoats – but humans. And for conservationists around the world, how the New Zealand public is convinced to not only support the predator-free goal, but to actively participate as well, may be the most valuable lesson to come out of the enterprise. 

Developing the technology needed to kill the tens of millions of predatory mammals in the country will be difficult, but it will be a matter of when, not if, experts say. Social acceptance and participation, they say, is a much more complex challenge. 

There are simple, traditional concerns, such as the use of toxins. But there are knottier problems as well. The possum fur trade is reportedly worth $130 million a year, with some trappers pulling in six figures annually. Some Kiwis worry that revitalizing native species could create new ecological and social problems. Others aren’t enamored with the idea that more native wildlife could mean more tourism.

Rakiura Island (or Stewart Island) is a living example of some of the challenges mainland New Zealand may have to contend with in the coming decades.

The island – a few miles off the southern coast of New Zealand’s Southern Island – is mostly a national park, but it has one town with a permanent population of 400 people, one school, one general store, and one 15-mile road that connects it all. The DOC and the Morgan Foundation, a philanthropic organization, have been funding a predator-free effort there for several years, but some of the locals – particularly those who enjoy the harsh, sub-Antarctic seclusion of the island – have expressed reservations. 

“Traditionally we’ve been a fishing community, so the move to tourism is not always welcomed by people,” says Sandy King, who has lived in the town, Oban, for 50 years. “There are lots of strange faces around. They fill up the shop.”

Some residents oppose the construction of predator-proof fencing because they would feel “like they’re being fenced in,” Ms. King says. Others are worried about the use of toxins or the possibility of reinvasions if eradication is successful.

Wild ambassadors

The most powerful ambassadors in the quest to bring a wary public along with the idea may not be conservationists, but the animals they are trying to save. There may be no better example of this than Wellington, New Zealand's capital.

In 1999 a 556-acre ecosanctuary, surrounded by a 5.3-mile predator-proof fence, opened on the edge of the Wellington city suburbs. Eighteen species of native wildlife have been reintroduced into the Zealandia sanctuary, six of which have been absent from the New Zealand mainland for more than a century. A large native parrot called the Kākā, for example, has grown from a population of six to more than 800.

But as impressive as Zealandia has been in reviving endangered native species, perhaps even more impressive is the effect it’s been having on Wellingtonians.

As species, particularly birds like the Kākā, have regenerated inside the sanctuary, they’ve journeyed outside the fence into the city itself, leading to a “proximity” or “halo” effect. As more people physically see the animals, they become more interested in protecting them, including through helping eradicate invasive predators.

Geoff Simmons, who lives a 20-minute drive from Zealandia, has witnessed this firsthand.

“Twenty years ago people would have known the Tui as a native bird, and that would have been about it,” says Mr. Simmons, an economist at the Morgan Foundation. “Now people talk about Kākā, Saddleback, Hihi. All these birds they never knew existed are appearing in their back yards, and once people have something they don’t want to lose it.”

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