By Dave Hansford

Two teal that have been released onto Campbell Island

In the drizzle sweeping down Perseverance Harbour, Pete McClelland, a programme manager with the Department of Conservation, slid open the front of a wooden box and, after a moment’s hesitation, a small brown duck emerged, slid down the bank into the raindrop-pattered water and swam away.

There were no speeches, no massed media, no ribbons. Yet this was one of conservation’s finest moments.

The Campbell Island teal had come home.

It’s a very different homeland to the one their forebears knew. The Dracophyllum scrub is back to head height now the sheep and cattle are gone, and the birds have an even chance of breeding after the cats died out, but Campbell has only just begun healing.

Back in 1810 the sealing gangs arrived to find a more verdant, more abundant place. But that was to change instantly. Their reeking ships held a deadly stowaway – the Norway rat.

The rats found an unimaginable bounty in the eggs and chicks of a million seabirds. A forest floor crawling with ground weta. And a little flightless duck that had never met a predatory mammal.

As its wildlife disappeared, Campbell Island became the most rat-infested place in the world.

A single sighting in 1944 was the world’s only glimpse of the teal until 1975, when Wildlife Service ranger Rodney Russ made a diving tackle in the tussocks of Dent Island to finally secure the first bird in the hand.

Dent is a tiny, precipitous shard of granite about three kilometres off the northwest coast of Campbell Island. At its feet the Southern Ocean heaves and moans, swirling tendrous forests of leathery bull kelp.

The islet was a lifeboat – the last rat-free refuge for what was now the world’s rarest duck. Russ and his colleague, Murray Williams, figured that 30, maybe 50 at most clung to life here by eating the regurgitations and droppings of seabirds, and the insects they attracted.

In 1984, the Wildlife Service sent a party back to Dent to rescue the besieged teal. The idea was to breed the birds in captivity on the mainland as insurance against rats ever invading the island. The frigate Canterbury returned with three females and a lone male, Swampy.

At first, the evacuees were kept as pairs in aviaries at the National Wildlife Centre at Mount Bruce in the Wairarapa, but they were reluctant to save themselves. Nothing happened. More birds were brought from Dent in 1990, but by 1993 not a single egg had been laid.

So staff tried another tack; they built aviaries big enough to house a flock at a time, and left the females to choose their own mates. Eureka. In 1995, the Campbell Island teal took its first step back from the waiting jaws of extinction. Swampy went on to father eight priceless ducklings.

Back then, McClelland saw the teals’ repatriation as fantasy; as long as the rats owned Campbell Island there would be no going home.

But on other fronts, the war on rodents was going well. In 1989, the Conservation Department rid Mana Island, off the northwest Wellington coast, of its 15 million mice. Then rats were eliminated on Breaksea Island in Fiordland, followed by Ulva, Whenua Hou and in 1996, the biggest to date – Kapiti.

For the first time, McClelland dared to dream about getting rid of Campbell’s rats.

“But it was a quantum leap - Campbell was five times the size of anything we’d done. It was cold, it was remote. The weather was foul.”

His team considered the problems one by one. They figured that it would take at least 200 tonnes of bait to do the job.

But Campbell’s weather would never let that happen. The only way round it was to reduce the amount of poison. “We thought we could lay six kilograms a hectare and still get the job done,” he says.

In 1999 he set out to prove it, dropping non-toxic baits over a 600-hectare trial zone on the island. “Then we trapped right through the area. We caught hundreds of rats and every one of them was pink inside – it had taken a bait. If the bait had had poison in it, the rat would have been dead.”

The trial showed that eradication was possible. The fortunes of the Campbell Island teal, and countless thousands of other birds, had just taken a turn for the better.

He had his bait. He got the money. Now McClelland needed a very special breed of helicopter pilot. “Success would stand or fall on their skill,” he recalls. “There’s a world of difference between pest control and pest eradication, where you can’t leave a single square metre uncovered. We needed pilots who knew that difference.”

They also had to be able to fly in Campbell’s atrocious weather. And the zinger; the drop had to happen in the dead of the subantarctic winter.

“We couldn’t risk harming any other wildlife,” says McClelland. “Either with the poison or by disturbing them with the helicopters.”

Nor could he expose his pilots to the very real danger of bird strike. So the operation was timed for when the birds had all returned to sea, which fortuitously was also when the rats had finished their own breeding (no danger of a pregnant female escaping the drop) and would be at their hungriest.

DoC recruited its pilots from the rugged, rain-lashed mountains of Fiordland. They flew the poison on a block at a time, moving across the island in a broad front whenever the weather allowed, using global positioning satellite instruments to apply a generoust overlap between blocks. They took their Jet Rangers to within metres of Campbell’s vertiginous cliffs.

McClelland left nothing to chance. If it rained enough to risk dissolving the baits, he ordered his pilots to go back and do another drop as soon as the weather cleared. His team fitted radio collars to a few rats so they could track them after a drop just to make sure. They were all found dead.

In the end, the weather – for the subantarctic – was kind, and the team did in 26 days what McClelland had budgeted for 100.

In 2003, staff returned to Campbell with a specially trained dog to look for survivors. They found none. Conservation history had happened.

McClelland won’t officially declare the island rat-free until 2006, just in case (“Never underestimate a rat”) but he was in a hurry to take his teal home.

“There was a risk they’d turn into cage birds,” he says. “They were living the life of Riley up at Mount Bruce. We actually had to slim them down before we brought them back to Campbell. Take a couch potato and run it in a marathon and it’s not going to last too well.”

He needn’t have worried. “They’ve proved to be amazingly adaptable. We had set ideas about the kind of habitat they would need, but these guys have blown all of that out of the water. We tracked one to 150 metres above sea level in sub-alpine scrub. It’s quite incredible.”

For McClelland, there are other islands to rescue - DoC is already preparing for an assault on Auckland Island’s pigs and cats – but he says Campbell was as tough as it’s likely to get.

Inspired by DoC’s success, Australia will now take the fight to rats on one of its own subantarctic islands, Macquarie. And the United States Wildlife Service is ready to reclaim some of the islands in the Aleutian group off Alaska.

In early October, the last of 50 teal were released into Perseverance Harbour. One was let go by Pete Kempster. He was a midshipman aboard Canterbury in 1984 when she evacuated Swampy and his cohort. Twenty years later, Kempster, now the frigate’s Commander, had brought them home.

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