Perils of paradise on Raoul Island

Berwyn Davies recalls sidestepping sooty tern eggs on the fine black gravel beach at Denham Bay in the early 1950s. Fifty years later he went back to the pohutukawa-lined bay on Raoul Island's southwestern side. There were no sooty tern eggs.

Since people first set foot on Raoul, nature and mankind have engaged in a brutal struggle. Pests and plants introduced by humans have had a merciless effect on the natural environment, including sooty terns; the rugged, volcanic land has had an exacting effect on the humans.

Ian Hankin met his partner Kim Morton while spending 1998 clearing weeds on Raoul. Morton had harboured a childhood fascination with the island, reading and re-reading a novel about the pioneering family of Thomas Bell, who settled there in the 1870s. The book, written by her distant relative, Elsie K. Morton, in the 1950s, is based on the diaries of two of Bell's 11 children.

The family's efforts to tame the subtropical island paradise, 1000km from civilisation, would end in ruin. If cyclones and rats weren't destroying crops, frequent earthquakes and volcanic outbursts would see settlers off.

Last week, Mark Kearney died on Raoul. He was taking a temperature reading in Green Lake, one of two crater lakes on Raoul, when it erupted. Kearney, 33, was trying to save paradise from weeds introduced by Bell and other early occupiers.

The explosion was nowhere near as big as the last major eruption, in 1964, but it dumped a 5m-deep layer of ash around the crater. "It's a reminder that the island is a natural environment with its own energy and its own force," says Morton. "Unfortunately he was right in there at that moment."

The island rises sheer from the ocean, as imposing and mysterious as Little Barrier, which is similar in size.

Traversing Raoul from north to south is a difficult five-hour tramp over crumbling, porous stone, negotiating steep ravines by clinging to ropes or foliage.

"It's rugged, it's very tough," says photographer Julia Brooke-White, who worked on the island as a volunteer in 2001 and returned the next year.

"It's very young - you get that feeling. The ground is very dry, gritty and crumbly, like Rangitoto. It's very porous. It rains heavily but there are no streams."

Morton and Hankin, now of Lyttelton, recall frequent earthquakes on Raoul. They were always conscious that the volcano was active, steam rising from the crater as they skirted the unstable slopes looking for weeds.

"It was very hot in places. You had to be aware of the risk of falling into a fumarole [volcanic vent]," says Hankin, who once fell up to his knees in one obscured by the undergrowth.

Dense with vines

Towering Kermadec pohutukawa and nikau forest dominate the island, but the understorey in places is dense with introduced vines - mysore thorn, passionfruit, grapes and guavas - and a flowering shrub, the Brazilian buttercup bush, which outcompetes the natives. The vines can completely smother the canopy, destroying the forest. Mysore is "like a wild rose times 10," says one veteran.

New Zealanders have been trying to stem the tide of introduced pests since the 1960s, when a goat eradication programme began. The last goat was shot in 1986. They weren't just browsing on the undergrowth, they would scale the pohutukawas and destroy the crown foliage, says Department of Conservation pest programme manager Carol West.

The recovery of the canopy has made the forest floor again too dark for another pest, the aroid lily, to thrive. That's allowing the weed management programme to focus on mysore and Brazilian buttercup. They are under control but it's an endless vigil because of seeds that can lie dormant in the rich volcanic soil for decades before sprouting.

The five DoC staff, who spend a year on the island, and nine volunteers, who come for four months, divide the island up and grid-search weed areas twice a year.

The operation costs about $240,000 a year, including staff salaries, running costs, maintenance and transportation. In 2003, $1 million was spent to wipe out rats and cats. Why invest so much in an inhospitable, eroding outpost few people will ever set foot on?

Raoul has high endemism - things that grow nowhere else, says West. Almost every shrub is endemic, "which is high biodiversity in a national context".

Apart from the island's own species of pohutukawa and nikau, there are ngaio, mapou, a rare hebe and a score of others.

Raoul is the largest of the Kermadecs group of 15 islands, important breeding places for petrel and shearwater species. Five of its bird species are unique to the island. And it is surrounded by a marine reserve with outstanding fauna, including a huge black spotted grouper, giant limpets, sea snakes and turtles.

Raoul's location makes it an ecological treasure trove: at 30 deg S it sits at the southern limit for many tropical species. Its seas are a convergence zone of temperate and tropical masses; proximity to the fathomless Kermadec trench makes the water cooler than expected. The islands themselves are part of a chain of volcanoes and seamounts (undersea volcanoes) stretching from Ruapehu to Tonga.

The weather station provides early warning of tropical storms which may threaten New Zealand. Its seismograph is of similar value to GNS Science. Its ecological values are of prime importance.

Denham Bay is the only place on Raoul where sooty terns can breed. With the rats and cats gone, seabirds are returning, including the red crown parakeet, or kakariki. "That means the nutrient inputs from the marine environment which the seabirds used to bring to the island will be restored," says West. "That in turn will feed the forest which will allow it to grow."

A rocky outcrop just offshore, the Meyers, reveals Raoul's past and potential future.

"You don't find crabs on [Raoul's] rocky shore, you don't find an endemic limpet attached to rocks," says West. "There's no lichens on the rocks, yet lichen is abundant on the Meyers. All of these are indicators of the pressure that the rats, cats and goats have put on the main island.

Expensive

"Those things will just recolonise. It will all happen naturally but it will take just a bit of time. It's expensive keeping people on the island but we make investments like that on the mainland all the time."

Commitment to conservation is not the only reason people queue to join the programme.

"It's seen as a unique opportunity to get away from the trappings of modern life, live in a small community and live in a landscape that's quite rugged," says Kim Morton. "It's a place of freedom where people can find out a bit about themselves in situations they haven't come across before - coping with the remoteness. You're not able to catch up with friends; you have to make do with people on the island."

It's not uncommon for long-term relationships to develop - the island reveals character. But inevitably conflicts arise.

"Someone does something irritating that wouldn't become a problem on the mainland. It's like reality TV without the money at the end and without the contrived situations."

Morton read the diaries of those who worked on Raoul in the 1950s and 1960s, and on her return began recording their oral histories for the Alexander Turnbull Library. It's hoped they will soon be publicly accessible.

"People I interviewed said the island gets under your skin," she says. "It has this huge impact on people's lives."

Like many, Julia Brooke-White enjoyed her first four-month stint as a volunteer so much she returned for a year as one of the paid team.

"It's like 'stop the world I want to get off' sort of thing. I was in a tiny hut on the island when September 11 happened. You couldn't be further away from disasters of the world."

Weed management occupies four days of the working week; maintenance the fifth. There are tasks such as the weather station, seismograph, testing the lake temperature, track repair and maintaining the generator.

It's not all hard work. The DoC base on the island's northern terraces is a comfortable 1930s house; the vollies (volunteers) stay in an annex. There's a video player and classic old records - Ian Hankin fondly recalls some Russian vinyl left by visiting sailors. There is singing and "outrageous" parties.

Weekends are a chance to explore and spend a night in a hut, or under the stars, says Phil Clerke, team leader on Raoul in 1998-99 and these days a DoC ranger in Marlborough.

And there's snorkelling. "You could see black spotted grouper in six to eight feet of water that weighed more than me. Even if you saw nothing the clarity of the water was gobsmacking."

Berwyn Davies spent two years on Raoul as a handyman in the early 1950s, when the island was an important weather station for shipping and aircraft. He spent his 21st birthday there. Now 73, the Whakatane man went back last year when adventure tourism company Heritage Expeditions made a first trip to Raoul.

"A large amount of money has gone into it,"says. "They've removed a lot of noxious weeds but it will be a never-ending job. Terns used to nest on the beach - they were just thick. They will come back."