Sharon Hubert

Landlocked islands

Until recently most New Zealanders were resigned to never seeing a kiwi except in a glassed enclosure. Few even knew of the existence of whiteheads, stitchbirds or North Island robins. Then came the idea of the mainland island. Get rid of the rats, stoats and possums in an area—as conservationists had on some offshore islands­ and it might be possible to bring back the birds. That was the theory—and it’s worked. Now there are dozens, even hundreds, of projects throughout the country in which people are getting their hands bloody for the good of native biodiversity—although it isn’t quite as simple as one might think.

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From its seaward end, the Tawharanui Peninsula can be seen to be a finger of land with a particularly rugged coastline, which is carved out of 150 million year old greywacke. The regional park includes all the peninsula and much of the sandy beach seen towards the distant right of the photograph, but not the forest behind it.
Fifteen kiwi were released in Tawharanui late in 2006 and it is hoped that they will soon start to breed.
Fifteen kiwi were released in Tawharanui late in 2006 and it is hoped that they will soon start to breed.

Natural-Heritage scientist Tim Lovegrove was on his hands and knees on a sheer-sided ridge in Tawharanui Regional Park, his head and torso facing a dense clump of bracken. Percy, an Eng‑lish setter, was staring in the same direction, his body tense, his tail high.

“Sighting!” yelled Lovegrove suddenly, be­fore disappearing into the bracken as fast as a rabbit. A few moments later, he emerged cra­dling a large, wriggling brown kiwi.

There were four scientists, two dogs and a journalist in the park. Their mission was to find the males of the 15 Apteryx mantelli released, amid much celebration, in Tawharanui Open Sanctuary in late 2006. The breeding season was due, and the scientists wanted to replace the monitors banded to the birds’ legs with “egg-timers”, miniature transmitters encased in brown plastic that emit a particular signal when a kiwi is sitting on an egg. Given the effort of laying a kiwi egg—which, proportionate to the parent bird, should be the size of a hen’s but is actually closer to that of a giant moa’s—it is only fair that the male incubates it, even if the task takes 70–80 days.

Looking for half a dozen kiwi in 600 ha is like looking for six needles in a large field of hay, but the scientists had specialist help. James Fraser, former Department of Conservation (DOC) worker and now bird-chaser for hire, had brought along Percy and Breeze, lean, lovely and beautifully behaved dogs trained to sniff out native ground-dwelling birds. Birgit Zeisemann, who was doing a PhD on the mating behaviour of kiwi, had a transmission box and what looked like a television aerial, which she waved in the air every few steps. Lovegrove, employed by Auckland Regional Council (ARC), had several decades of ornithological experience behind him and a legendary level of fitness that allowed him to traverse large tracts of dense bush at aston­ishing speed. Also present was a student of environmental science from the Netherlands, who had long legs and had been doing this sort of the thing for the past three months. The journalist, the least prepared, could only try to keep up.

The most abundant native bird in the reserve is surely the fantail, breeding freely now without harassment from rats (see NZ Geo issue 55). Native invertebrates, such as peripatus (photographed at Maungatautari, bottom), are far less conspicuous but will also benefit hugely from the removal of rats in mainland islands.
The most abundant native bird in the reserve is surely the fantail, breeding freely now without harassment from rats (see NZ Geo issue 55). Native invertebrates, such as peripatus (photographed at Maungatautari, bottom), are far less conspicuous but will also benefit hugely from the removal of rats in mainland islands.


Earlier in the morning, the transmitter had led the group to a large puriri tree in the middle of the bush. The detector unit had beeped insist­ently when placed anywhere near the base. Eve­ryone had wandered round the tree helplessly. Breeze had stuck his nose longingly into a small cavern among the roots. Kereru had swooped overhead, swishing like soft, and possibly sarcas­tic, applause.

There was nothing to be done; he was in there but he wasn’t coming out.

“Well, he certainly has a very nice burrow,” said Zeisemann, as she shrugged, tied a pink rib­bon round the tree as a marker and trudged off. She had picked up a signal somewhere else in the park—a beep like any other to the untrained ear but sufficient for her to lead us to the other side of the park, up a hill, through some bush and up another ridge to where the forest opened into farmland, before pausing and pointing at a large patch of metre-high kikuyu grass.

The beep was strong. Something rustled. The beep grew weaker. The signal was stronger again a few metres to the right. Everyone formed a circle, got down on their hands and knees and began to grope around in the kikuyu. Eventu­ally the student murmured, “Got it,” and gently pulled the male kiwi known as 57 out of his lair. He didn’t seem to mind, even appeared quite re­laxed, although it wasn’t clear whether this was in fact the case or he was terrified and playing dead.

“Kikuyu grass,” marvelled Lovegrove. “They just pick the shittiest habitats. Farmland is per­fect for them. They can hide in the grass by day, and then come out at night and flick the bugs off the cowpats.”

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Who would have thought, five years ago, that 15 of the country’s avian icons would be allowed to roam free in a regional park on a peninsula in the Hauraki Gulf, a mere 90 km north of Auck­land? Tawharanui is loved for its open bays of white sand and translucent water. It is a mixed landscape of farmland, wetland and patches of native bush that still contain some impressive totara, nikau, puriri and taraire.

There is also a camping ground. Its facili­ties don’t extend beyond a few long drops and taps but it is usually booked out months ahead. People who spend Christmas there tend not to tell anyone else about it in order to ensure their space is safe, year after year.

The park has recently been fenced off with 2.5 km of predator-proof fence, running across the peninsula from coast to coast. It is New Zea­land’s first open sanctuary, “open” because you don’t need a special permit to go there. You can even stay after dark, along with the 15 resident kiwis. Twenty-one North Island robins have also been released there, along with 70 whiteheads. Some 100 bellbirds have turned up of their own accord, probably from Little Barrier Island. There are also grey warblers, kereru, shining cuckoos and possibly a tomtit. Terns and dotter­els wander along the beach.

Although a fence protects Tawharanui, traps and poisoned bait stations are still scattered about as a second line of defence, particularly necessary along the coast where the fence cannot extend across the tidal beach.
Although a fence protects Tawharanui, traps and poisoned bait stations are still scattered about as a second line of defence, particularly necessary along the coast where the fence cannot extend across the tidal beach.

The sanctuary is the result of a partnership between ARC and a large group of 400 or so vol­unteers known as the Tawharanui Open Sanc­tuary Society Incorporated (TOSSI). Without ARC there would be no regional park, but without TOSSI there would be no TOS.

Since its inception, TOSSI has raised around half a million dollars. The fence cost about $700,000, $200,000 coming from ARC, another $200,000 from New Zealand Lotteries, and the rest from TOSSI. TOSSI has also contributed hundreds of hours of human labour and has re­cently built its own nursery growing 20,000 plants, half of which are earmarked for the res­toration of a wetland to which brown teal will eventually be introduced.

Completion of the fence, in 2004, was fol­lowed by an aerial poisoned-bait drop to kill un­wanted animals inside the enclosure. Ten species of mammal were targeted and seven were elimi­nated. Hedgehogs (some of which were possibly asleep at the time of the drop) and rabbits (which are notoriously bait-shy) persist, but their numbers are low and they aren’t expected to last much longer. It’s the mice that have everyone stumped—those small, elusive, furry rodents, astonishingly adaptable and exceptionally catho­lic in their breeding and feeding habits.

Mice began to show up in tracking tunnels at the beginning of 2005, three months after the bait drop, and with rats no longer there to eat them and their food, they began to multiply co­piously. By the beginning of 2006 campers were reporting them inside their tents, even on their pillows.

Anyone who has been to Queensland, where the roads are sometimes clothed in the fur of squashed rodents, will know the difference be­tween a lot of mice and a plague of mice. Tawha­ranui isn’t afflicted by the latter, but there are enough of the little creatures to cause a modi­cum of alarm. The question everyone would like to know the answer to, although they probably never will, is whether mice got inside the fence after the bait drop, or whether the bait failed to kill them.

At Maungatautari Ecological Island in the Waikato south of Cambridge, a pair of young takahe have been introduced—a return to the northern North Island mainland after an absence of more than a century.

Either way, it was thought likely that mice would make an appearance after the drop, but those involved couldn’t help but hope other­wise.

“Sometimes I feel like I failed at Tawharanui, because of the mice,” says former project man­ager Jo Ritchie. “But that’s partly my own na­ivety. You set really high standards and then you want to prove that you can actually do it.”

Her theory is that mice territories are tiny, and a patch of metre-high kikuyu grass is, from a mouse’s perspective, equivalent to an apartment block several storeys high. It’s quite feasible that the bait didn’t land in every apartment.

But for every low there is a high. Ritchie re­members Lovegrove ringing her up to tell her about the bellbirds.

“He said, ‘Jo, there are bellbirds at Tawha­ranui!’ I said don’t be so stupid. He said, ‘There are about 200!’ I just couldn’t believe it. And now they’re breeding. There are chicks everywhere, and tui chicks, and pheasant chicks. It’s a really abundant place. And it all culminated with get­ting the kiwi back after a 40-year absence. That’s pretty huge.”

[Chapter Break]

Events at Tawharanui are being mirrored all over the country as groups of envi­ronmentally minded citizens prepare to get their brows sweaty and their hands bloody for the sake of enhancing native biodi­versity. Mostly they’re motivated by a desire to bring back the birds. Birds tend to captivate peo­ple in ways that, say, small insects don’t.

The places they seek to restore to some sem­blance of their pre-mammalian state are com­monly referred to as mainland islands. Some projects involve ongoing intensive predator con­trol, others have opted for an aerial bait drop inside a predator-proof fence. Some are just a few hectares in area, others cover many square kilometres. Maungatautari Ecological Island Trust has ring-fenced 3400 ha of forested vol­canic cone in the Waikato basin. This is a larger area than Little Barrier Island. Te Moehau Kiwi Sanctuary, at the northern tip of Coromandel Peninsula, isn’t fenced (there was some talk of fencing it but the idea has fallen out of favour) but predator control is being carried out over 12,000 ha, as well as on 5000 ha of private land on Kuaotunu Peninsula, north of Whitianga.

The term mainland island derives from the conservation work done on many offshore is‑lands in the 1970s, 80s and 90s. New Zealand has over 600 islands in its territory, and in climatic zones that range from subtropical to subantarc­tic. Many of these have never been reached by pest mammals and they have provided excellent refuges for birds on the brink of extinction, most famously in the case of the black robin, which, its population reduced to five, was saved by Don Merton et al and the reproductive capacity of a single female, Old Blue, on Mangere Island.

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It’s largerly because New Zealand is an is­land (or at least a collection of islands) that its ecosystem is vulnerable in the first place. An island’s biogeographical isolation from the larger continental landmasses is never abso­lute, but may be sufficient for evolution to devi­ate significantly from the mainstream. Should the outside world eventually arrive on the island (which, given human mobility and the cargo of plants and animals people carry with them on their peregrinations, it inevitably does), the con­sequences for many of the local inhabitants are generally catastrophic.

In New Zealand, an extensive avifauna evolved in the absence of mammalian predators. The forest floor, normally the domain of hungry furry quadrupeds, was thus a place where birds could safely hang out. For many species, the ad­vantages of flying less, or even giving up flight­ a notoriously high-energy activity—outweighed the benefits of maintaining the ability.

Only a mammal-free island could have pro­duced a nocturnal flightless parrot whose sole mode of self-preservation in the face of danger is to freeze. This was undoubtedly effective when eluding the sharp-eyed and now-extinct giant eagle Harpagornis—the kakapo’s camouflage is second to none—but is quite useless as a means of escaping something that hunts with its nose, especially if you emit a scent as strong and entic­ing as the kakapo’s.

Mainland island areas try to include a wide variety of habitats to protect as diverse a range of species as possible. Hence Tawharanui includes coastal forest, shrublands, dunes, wetlands, and pasture.

While the kakapo, thanks to an intensive management programme, has been saved from extinction (for the time being at least), an esti­mated 49 species of non-marine endemic birds have disappeared from New Zealand. As Ameri­can scientist Jared Diamond has put it: “New Zealand no longer has an avifauna, just the wreckage of one.”

Islands provide an excellent test bed in which to assess relatively quickly the impact of one spe­cies on another. It was work on islands that led to the realisation that it wasn’t so much habitat loss that was devastating New Zealand’s native bird species, as rats and mustelids dining on eggs, chicks and incubating females. Lovegrove, while monitoring saddlebacks released on Kapiti Island in the 1970s, revealed the impact that rats were having on the ground-nesting birds by preying on adults as they slept at night. “We knew they were vulnerable,” he says, “but they were five or six times more vulnerable than we thought.”

It was on islands, too, that New Zealand bi­ologists first imagined they could get rid of the mammals causing all the destruction. Several successful attempts were made in the early dec­ades of the 20th century to clear islands of rabbits (Tiritiri Matangi), cats (Stephens Island), pigs (Poor Knights Islands) and goats (Great Island, in the Three Kings group). In the early 1960s, Merton led a group of volunteers in the first successful effort to clear an island of rats—four islands, in fact, albeit small ones, in the Noises group about 20 km from downtown Auckland. However, it wasn’t until the mid-1980s that rats were generally accepted as being a menace to na­tive wildlife and that there was any consensus on the feasibility of ridding islands of them.

The 170 ha Breaksea Island in Fiordland, de­clared rat-free in 1988, was the first large island in the world to be cleared of rats. Ulva Island, Whenua Hou/Codfish Island and dozens of oth­ers followed. The largest and most ambitious eradication programme to date was carried out on Campbell Island, declared rat-free in 2003.

Inspired by their offshore successes, scientists began to entertain the idea of using the same ap­proach on the mainland. There was also some pressure to do so. Apart from a shortage of is­lands suitable for making into additional ref­uges, New Zealanders wanted to see the results of the conservation efforts they were paying for. They also wanted DOC to start doing some­thing about the degraded state of their own local patch of bush.

In the mid-1990s, DOC designated six areas mainland islands. These would represent a new approach to restoring damaged ecosystems on the mainland, using intensive, integrated and sustained pest control. But they may never have come about if it hadn’t been for the success of their kokako recovery programme at Mapara Wildlife Reserve, in the King Country, which had begun five years previously.

The uncommon and patchily distributed Hochstetter’s frog has also been recently discovered living on the mountain.

The project was led by scientist John Innes, now with Landcare Research and famous in con­servation circles as the Rat Man or, presumably preferably, the Kokako Man. Using portable time-lapse infrared video cameras, Innes and his colleagues recorded possums taking kokako eggs. (They thought that possums might also be preying on the birds themselves but were unable to confirm this.) They were also able to demonstrate just how low pest numbers had to be before there would be any significant benefit to the kokako population. This was achieved, by intensive trapping and poisoning, and fledgling survival rates escalated.

“Mapara really got everyone thinking,” says Alan Saunders, former mainland-island coordi­nator at DOC (and now head of the Pacific In­vasives Initiative at the University of Auckland’s Tamaki campus, where he is working on eliminating cane toads from an island in Fiji). “The success of that blew everyone’s socks off, and the story was published internationally. The model was ‘We can increase the number within five years with intensive predator control.’ We were sceptical, but it just blew us away. There were something like seven pairs and six individuals to start with, and within five years they had 36 pairs.”

It was a few years later that Wellington-based Forest-and-Birder Jim Lynch came up with the idea of using the same techniques on a 252 ha decommissioned dam site two kilometres from the centre of the capital city. Karori Wildlife Sanctuary, New Zealand’s first large fully fenced reserve, was completed in 1999.

“The proximity to the city was seen as a huge opportunity for the community to get involved and to see conservation in action,” says the sanctuary’s conservation manager Raewyn Empson. “Until then conservation had largely been offshore, where most people would never get to see it.”

Inland Maungatautari rises to 797 m, so includes montane forest and a recently discovered stand of silver beech one of the northernmost occurrences of the species in the country.

Karori is now home to spotted kiwi, kaka, kereru, hihi (stitchbirds) and numerous other birds, along with giant weta, tuatara and Maud Island frogs.

“Because we were very successful it has been a great example to everyone,” says Empson. “It’s actually been a bit scary to be honest, because now so many other groups want to do this. And I think that sometimes there’s not enough aware­ness of the effort that’s involved, even in just maintaining a fence. People think you stick up a fence and stick in the birds, but we do huge amounts of surveillance and monitoring. We al­ways assume it can fail.”

The mainland-island concept has now be­come so popular that Bruce Burns, another sci­entist at Landcare Research, has set up a website ( that provides a forum for those involved in such projects. It lays out the shared aims of what it prefers to refer to as biodiversity sanctuaries: to get rid of the full suite of pest mammals; to reintroduce missing species, including those that are rare and endangered; and to involve the local community in the work of restoring the ecosystem to a state of native diversity and abundance. Forty sanctuaries are listed on the site, but there are now hundreds of groups pursuing similar goals.

“It’s exciting,” says Burns. “It’s quite a change in people’s attitudes toward conservation. In­stead of saying ‘Something must be done’, they’re actually doing something. It’s the emergence of community-led conservation.”

But can it last?

“That’s something I worry about. Is this sus­tainable, both financially and in terms of com­munity motivation?”

[Chapter Break]

A word of advice: bringing back the birds is not for the faint-hearted. Kill­ing small furry creatures isn’t always a particularly pleasant thing to do, al‑though people say you learn to close your eyes and think of the bellbirds. Spooning peanut butter onto bait stations might sound perfectly palatable, but getting to the stations may entail trudging long distances through dense bush and abseiling down ridges, holding onto supplejack for dear life. Sometimes it will rain on you. It can also get cold and muddy.

But the rewards can be surprisingly swift in coming. Ark in the Park, a Waitakere Forest and Bird–ARC joint venture, started out with an intensive predator-control programme on 250 ha of the Waitakere Ranges in 2003, in an area called Cascades Kauri Park, and has now expanded to cover 1100 ha. The rugged terrain makes a predator-proof fence impractical, prob­ably impossible, yet the numbers of possums, rats, stoats and feral cats have been sufficiently reduced for whiteheads and North Island robins to be released, while the bush is flourishing to a degree not seen for years. The greatest coup, however, has been the release of 60 hihi.

The last record of hihi on the mainland was from the 1880s, somewhere near Tararua. The species was thought to have gone the way of the huia, until a decent-sized population was found on Little Barrier Island, which is where 95 per cent of hihi still live. But now you can go for a walk around Cascades Kauri Park, a mere 40 minutes from the centre of Auckland, with a good chance of hearing hihi and a reason­able chance of seeing one—both oddly moving experiences.

Both Tawharanui and Maungatautari are protected by locally designed Xcluder pest-proof fences. These have a 5 mm mesh—thought to be small enough to keep out young mice—and a top shroud to block climbing animals.
Both Tawharanui and Maungatautari are protected by locally designed Xcluder pest-proof fences. These have a 5 mm mesh—thought to be small enough to keep out young mice—and a top shroud to block climbing animals.

This is only the second release of hihi on the mainland in 125 years (the first was at Karori). There are still a few predators about, but over­all the fauna around the Cascades is similar to that on Little Barrier, and it was time to test the bird’s survival capacity.

“It’s still experimental,” says Richard Grif­fiths, head of the Stitchbird Recovery Group. “But this is quite a big one because stitchbirds have never been released at a site where predators are present. We hope that, like the kokako, they will survive where predator numbers are low.”

While the outlook is hopeful, the effort of getting to this point can’t be underestimated. Karen Colgan, who co-ordinates the pro­gramme’s volunteers, has 180 people on her email list, half of whom are very active. She estimates that altogether the project requires around 600 volunteer hours each month. The many jobs to be done include baiting, trap­ping, bird-monitoring, pest-monitoring, track maintenance, planting and weed control (wild ginger, woolly nightshade and gorse are all ma­jor pest plants). There is bait to be bagged and hihi feeding stations and nesting boxes to be built. Someone has to organise the sausage siz­zle for the volunteer days. And then there’s the fundraising. One ingenious volunteer collects golf balls that have strayed into the bush from a neighbouring golf course and sells them on TradeMe. Sum raised so far: $3000.

Another piece of advice: get yourself one of those visionaries, the kind with an unshakeable faith in the idea who will maintain collective enthusiasm when the going gets really tough. Someone like David Wallace, a rich Waikato farmer with excellent connections, the gift of the gab and remarkable powers of persuasion, whose idea it was to fence off a mountain.

Wallace was initially inspired by a docu­mentary about rat-trapping on Breaksea Island, which prompted him to start experimenting with the same techniques on his farm. Together with three others, he developed a predator-con­trol fence. First erected in 1999 round a 16 ha block on his land called Warrenheip (the same year the fence at Karori was completed), it is now marketed as Xcluder and has been used at Tawharanui and Maungatautari.

At Tawharanui (upper) a number of areas are being re-vegetated with natives. The face on the right was planted some years ago and natives will be planted in the sprayed kikuyu extending into the foreground.
At Tawharanui (upper) a number of areas are being re-vegetated with natives. The face on the right was planted some years ago and natives will be planted in the sprayed kikuyu extending into the foreground.


Warrenheip has built an excellent reputa­tion as a kiwi sanctuary. Operation Nest Egg, which removes kiwi eggs from the wild, incu­bates them at Rainbow Springs in Rotorua and raises the chicks in a predator-free environment until they’re big enough to fend for themselves, has relied on Warrenheip. About 60 kiwi chicks have grown up there. If Wallace’s proposal for a mainland island at Maungatautari initially sounded preposterous, Warrenheip helped persuade people it wasn’t so.

Wallace, a man of the times, represents yet another shift in approach to conservation, being determined to marry environmental goals with business imperatives. Maungatautari Ecologi­cal Island Trust is exploring ways of making the project “financially self-sustaining”. And when Wallace says they’ll get rid of the mice, you tend to believe him. There have been two aerial bait drops and another one is due in 2007.

“We’ve got rid of almost everything,” he says cheerfully. “We’ve got a few goats left, probably about 10 or 15. There’s no sign of any rats, the hedgehogs and pigs have all gone, and there’s only the odd rabbit.” There are pockets of mice, about 20 of them, “But we also have 160 km of monitoring line, and every 100 m there’s a track­ing tunnel. I’m thinking that we might have to double these tracking lines to be successful. If we can find the pockets, then we have the capac­ity to get rid of them. We talk a lot about getting the last mouse out. I’ll be happy when we get the last mouse off the mountain.”


Down in Karori, they’ve been grappling with mice for much of the eight years since the fence was put up. Empson is certain they got rid of all those inside enclosure initially but that more have since found their way in. In the first place, no mice showed up until six months after the aerial bait drop. In the second, the fence mesh can be damaged—and has been—when, for ex­ample, someone biking round the outside runs into it. This might result in only a millimetre of distortion in the fine mesh, but that can be enough to allow a mouse through. The current plan is to manage mice through annual baiting, although the long-term intention is to replace the fence with one that has a finer weave.

Eliminating mice once and for all, however, is likely to remain a pipe dream.

“The thing about fences is that they can’t pre­vent birds themselves from bringing mice back in,” says Empson. “We’ve seen several kaka car­rying mice around. We know harriers and more­porks do that, too. There’s even anecdotal evidence of harriers carrying stoats. And you only need one of them to be pregnant…”

[Chapter Break]

In the end, mice could be considered a sym‑bol of the modern ecological predicament. Scratch the surface of the restoration-project philosophy and it becomes apparent that while the motivation behind it is admirable and its achievements rewarding, the premise on which it’s founded doesn’t always make perfect sense. What do people mean when they talk about “original” or “pre-human” ecological systems?

“Good question,” says Matt Maitland, re­cently appointed project manager for Tauwha­ranui. “Everyone says they want to restore, but then you say, well, restore to what?”

Maitland has spent much of the past eight years working at Rotoiti Mainland Island, in Nelson Lakes National Park, trying to get rid of exotic wasps. (DOC has eradicated wasps from 11,000 ha, resulting in a visible improvement in the health of the beech forest, but that’s another story.)

“Perhaps we need to embrace the new ecology to some extent,” he says. “Just because some­thing is exotic doesn’t mean that it’s nasty or pesty. And if it’s nasty in one area, it might not be nasty in another.”

As evidence, he points to gorse, an invasive pest, but a plant that serves as a useful nurse-crop for native trees and shrubs. He points also to the plum trees planted by DOC officers at Mapara as a food source for kokako. And to Maud Island where kakapo fed on pine trees.

It doesn’t stop there, either. One might say by all means get rid of the mice, but what about the sparrows and blackbirds?

“Exactly,” says Maitland. “Here in New Zea­land we’ve lumped every mammal into the nasty basket, and put most exotic plants into the nasty basket, but we’ve put few exotic birds into the nasty basket, despite the fact that they’re very successful at competing with natives. We do play favourites.”

The whole point of Tawharanui was to elimi­nate all the mammals, and while that goal will be pursued, Maitland gives the impression that he has yet to be convinced it’s an achievable, let alone a sustainable, one.

This species of native orchid is just one of scores of plant taxa that flourish on Maungatautari. Without possums eating leaves and flowers and rodents devouring seeds, plants also prosper in mainland islands.

“We have embarked on establishing this as an open sanctuary, and we have invited people to come and go. And we invite them to enforce their own biosecurity habits, but we can’t enforce that. We’re just saying ‘Please do it.’ But you’ve got to think about the reality. How many people really shake out their tents before they go up to Tawha­ranui to make sure they haven’t got any mice? But we also have to look at what are the real impacts of limited mice. We can’t take it as blind dogma that all exotic mammals are bad.”

Could you argue that, in the evolutionary scheme of things, all these efforts are only de­laying the inevitable?

“Oh, I don’t really get caught in the evolution­ary argument,” says Maitland. “We’ve made mis­takes and we’re fixing them and I pretty much park it there. In our lifetime we can save species.”

And some species are safer, although not yet safe. There is a much greater understanding of what has been troubling them but so much more still to understand.

“Collectively we’re improving, but not stead­ily and consistently. It’s still in odd leaps and bounds. There is no rule book. We’re all making it up as we go along.”

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