Sir Paul Callaghan's crazy idea

by Rebecca Priestley / 14 April, 2012
In his final lecture, Sir Paul left behind an idea whose time has come: clearing the land of invaders.


When Sir Paul Callaghan died last month, the science community lost a great physicist, communicator, mentor, entrepreneur and visionary. But his last lecture, on February 13, was not about the nuclear magnetic resonance he’s known for in the physics world, or about his vision for a New Zealand economy boosted by a high-tech manufacturing sector.

February’s talk, though, did tie in with Callaghan’s vision for a New Zealand “where talent wants to live”. In front of a packed Wellington auditorium, Callaghan asked, “What do we have that marks us out as unique in the world?” England has Stonehenge, China has the Great Wall, France has the Lascaux cave paintings, he answered, but our heritage is our wildlife. Some of this heritage – the moa, the haast’s eagle, the huia – is already lost, but we still have taonga like the tuatara, kiwi, tui, kokako, saddleback and takahe, which have survived “against all we have thrown against them”.

But they are suffering. Although New Zealand’s island sanctuaries ably protect our wildlife, our mainland forests have never been so silent. Last June, Jan Wright, Parliamentary Commissioner for the Environment, said that without active management of our forests, “many of our iconic species are in danger of extinction”. Charles Daugherty, a professor of ecology at Victoria University and a trustee of Wellington’s Karori Sanctuary Trust, agrees. “Basically, our forests are dead. Yes, there are still trees in them, but they’re quiet. The birds are gone, they’re totally changed because of the introduced mammals.”

The Department of Conservation has an international reputation for island pest eradication, an intensive but relatively straightforward process involving aerial bait drops for possums and rats, trapping mustelids and cats, and shooting pigs, goats and deer. Ninety islands have so far been declared pest-free, including near-shore islands like Kapiti and Resolution, and distant islands like Raoul and Campbell, which in 2003 became the largest island to be declared pest-free.

Mainland sanctuaries are a recent innovation. In 2000, the Karori Wildlife Sanctuary, now called Zealandia, became pest-free. The 225ha urban sanctuary, surrounded by an 8.6km predator-proof fence, has been a tremendous success and is now home to breeding populations of native wildlife like kiwi, saddleback, bellbirds, tuatara, giant weta and Maud Island frogs. The benefits of the sanctuary, combined with region-wide pest control managed by the council, have extended across Wellington, creating what Zealandia founder Jim Lynch calls a “halo effect”: witness some churlish residents’ complaints about the raucous noise of morning tui and kaka in their gardens. Zealandia has become a model for other projects and there are now eight mainland sanctuaries around the country, from Tawharanui in Northland to Orokonui in Otago, with several others planned or under way.

In Callaghan’s February lecture, inspired by Zealandia’s success and Lynch’s vision, he presented “the crazy idea” of reviving New Zealand’s forests by creating a dozen 100,000ha restoration zones, about 15% of the current conservation estate. Taking advantage of the halo effect, each zone would have a fenced core of 1000ha, inside which all pests are eradicated. Outside, a further ring of up to 10,000ha could be managed with intensive trapping. An outer halo, taking each zone up to 100,000ha, could be managed with 1080 drops, without which “we don’t even have a chance of turning this thing around”. Callaghan said we could do this in 12 places – in forested areas like the Orongorongos near Wellington and the Whirinaki Forest in the Urewera – for $20 million a year, 20% of DoC’s existing biodiversity budget.

But then Callaghan suggested a “mad” idea, the New Zealand equivalent of the Apollo space programme, which he called the Zealandia programme. “Let’s get rid of the lot. Let’s get rid of all the damn mustelids, all the rats, all the possums, from the mainland islands of New Zealand. And we start with Rakiura [Stewart Island]. And we work our way up.”

Rather than being crazy, this could be an idea whose time has come. Early this year, Forest & Bird advocate Nicola Toki hosted a summit of 20 predator scientists and conservation workers on creating a predator-free New Zealand. “What was surprising was that using current methods, and given some expected advances in technology, the concept of a predator-free New Zealand was considered to be achievable. There was a healthy amount of debate about a range of techniques and acknowledgement of a need to wise-up on some basic ecology and behaviour of some of our least-known predators, but ultimately, the concept got the ‘we could do it’ tick,” says Toki.

The idea neatly turns on its head what happened 150 years ago when Acclimitisation Society members sat down and talked about all the things they might bring in. “So now we have the reverse, people are sitting around and thinking about the things they might kick out.”

It’s an urgent problem. “Every night when we go to bed, we’re losing hundreds of kiwi, they’re getting their throats ripped out. We’re losing kaka chicks, we’re losing kokako, we’re losing the things that define us.”

So where to from here? Toki’s group of scientists and conservation workers are hatching a plan. What everyone agrees is that such an ambitious scheme would take community involvement and buy-in on a massive scale. But anyone can start playing a part, even now. Toki says people who want to get involved in mainland pest eradication should contact their council, DoC or Forest & Bird, whose 70,000 members regularly spend weekends in parks and reserves working on conservation projects that mostly involve killing small furry animals.

As we eradicate pests, the forests can be restored. “New Zealand is, in many respects, an extraordinary place for ecological restoration because we know what the country was like before humans arrived. Meaningful bits of it survive on these offshore islands,” says Daugherty. Once the forests are restored, it’s just a matter of defending our borders. “We can defend our borders against spiders and snakes, we can sure as hell defend them against possums,” said Callaghan last month.

As anyone who ever worked with Sir Paul Callaghan knows, he was a man who got things done. So maybe, if the nation pulled together, we could do this. We could rid our islands of possums, rats, stoats and all the other introduced creatures that are destroying our birds and forests – our unique heritage – and create predator-free mainland forests in which our birds, reptiles, invertebrates and native flora could thrive.

As Callaghan said at the end of his February lecture, “It’s crazy and ambitious but I think it might be worth a shot.”

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