Rat and ruin
By Ruth Slavid
A rat eradication programme in one of the world’s most remote environments is to be applauded – but how many lessons does it have for the rest of the planet?
The island of South Georgia in the Antarctic has carried out the most ambitious rat eradication programme of any island anywhere in the world. And it has done it in a race against time – before the glaciers that divide the island into manageable zones retreat so far that the island becomes one happy playground for invading species.
The results so far have been stunning – rats have gone as far as can be told and colonies of the South Georgia pipit, the world’s most southerly songbird, are reappearing. Previously the bird had become restricted to outlying islands.
It is a success in its own terms, having surpassed earlier successes in New Zealand, and inspiring that country to even greater efforts. The island has also got rid of reindeer, an ill-considered introduction, and has strict biosecurity measures.
The tale is a fascinating one, but does raise the question of how often it can be emulated and whether it should be. South Georgia is a special place. Does it have lessons for the rest of the world?
To understand just how unusual South Georgia is, it is worth recalling that last December the astronaut Buzz Aldrin was evacuated from the South Pole after falling ill on a tourist trip, albeit one that few of us could afford. Tourists can, in the summer season, fly to the South Pole. But nobody has ever flown to South Georgia. The island is too rocky for an airstrip, and too far from anywhere else for helicopters to reach it.
Typically a cruise ship or equivalent takes two and a half days to cover the 1,550 km from the Falkland Islands to South Georgia. Any evacuations, for medical or other reasons, have to be by sea. There are no harbours, with all but the smallest ships having to moor offshore. The population is tiny, with between 20 and 25 people living there in the summer, fewer in the winter. They comprise Government officers (South Georgia is a British Overseas Territory), members of the British Antarctic Survey (BAS), and members of the South Georgia Heritage Trust, which runs the excellent museum on the island – and also ran the rat eradication programme.
But South Georgia has a far more populous history. In the first half of the twentieth century, it had several successful whaling stations, with the last one closing in 1965. Nobody then was worrying about environmental issues, and invading plants came in as well as rats.
Obviously nobody likes rats, but eliminating them in South Georgia was particularly important because of the island’s fragile ecology. Plants grow very slowly in the harsh climate, which means that invasive species may take a long time to establish, and can then be devastating. There is abundant animal life, but that is in terms of numbers rather than variety. The beaches in summer are covered in fur seals and elephant seals, and the king penguins, the dominant species, can be numbered in hundreds of thousands on the most ‘popular’ beaches. There are no land predators, which is why the effect of rats was so devastating. The South Georgia pipit had no skills for evading rats.
Tony Martin, professor of animal conservation at the University of Dundee, had worked on the British Antarctic Survey base on Bird Island, off South Georgia where 20 years ago it was discovered that the population of albatrosses was ‘going through the floor’ for a variety of reasons. When he travelled to the mainland of South Georgia he was struck by the ‘night and day’ difference in the population of South Georgia pipits, a difference that was down to the presence of rats.
The decision by the South Georgia Heritage Trust to eradicate the rats was, Martin said, ‘a completely barking mad idea from the beginning’. Prior to this, its main responsibility had been running the island’s museum – a wonderfully curated resource, but a small one. ‘It was fundraising for signage around the museum,’ Martin said. Then it undertook this massively ambitious project.
What does it matter what Martin thought? A lot, in fact, because in 2009 he received a call from the trust and jacked in his job with BAS in order to lead the project. The South Georgia Heritage Trust had set about raising the £7 million that was needed to carry out the work. This was done in three stages each of which was self-contained because of the presence of glaciers separating the areas.
This was covering a far larger area than had been done previously, either by New Zealand on Campbell Island, or by the Australians on Macquarie Island. South Georgia has a land area of 3,900 square kilometres, and nearly all of those are mountainous. Apart from at the ‘capital’ Grytviken, where there is a track stretching a couple of kilometres, there are no roads. And the eradication programme had to get rid of all the rats – getting rid of a lot would not be enough. The island had to be rat free.
‘Around the world all previous large-scale eradications had been carried out by governments,’ Martin said. ‘But the South Georgia government didn’t want to do it. So the South Georgia Heritage Trust said that they would do it. My job was to put at least one pellet in front of every rodent in South Georgia. How you do it is more complicated. Doing it by hand is out of the question.’
The trust bought three helicopters (which were delivered by sea) and equipped them with buckets slung beneath them to contain the bait, an anti- coagulant poison called Brodifacoum, which was coloured a bluish green since it had been determined that that was the colour least attractive to birds.
The reason for starting with a fairly small area was, said Martin, because, ‘as well as killing all the bad guys, you have to ensure that the mortality of non- target species is sustainable.’ In other words, had the first part of the trial led to unsustainable mortality in birds or seals, it could have been abandoned.
But it was a pretty good bet that this would not be a problem because South Georgia has no native mammals, reptiles or amphibians. And, said Martin, ‘seals won’t touch the pellets’. Birds were therefore the only potential collateral victims and the first phase of work, if it had gone horribly wrong, would ‘only’ have eliminated 10 per cent of the birds on the island – and it was reckoned they could have recovered.
The logistics were difficult for all stages of the work, not only because of the terrain but also the weather. One of the helicopters had its rotors bent out of shape in a ferocious storm despite being lashed down against the wind. Sophisticated GPS systems were used to ensure that the poison reached all the correct places.
And the rats have gone. Not only have the rat trails in the snow disappeared, and the South Georgia pipits reappeared, but a variety of telltales put out to identify the presence of rats have come up negative. And the South Georgia Heritage Trust has invested in some cute dogs to sniff out rats!
Rats are not the only possible invaders. Because vegetation grows slowly, and because temperatures are rising, there is concern that invasive plants could edge out some of the natives. An area of ground near King Edward Point, adjacent to Gritvyken, has been designated a no-go zone to prevent the spread of seeds from invaders. Visitors to the area are not allowed to put any bags down on the ground in case they carry seeds.
When cruise ships arrive, all visitors have to go through Virkon disinfectant baths before disembarking onto inflatable boats. And clothes and bags are checked and vacuumed to eliminate seeds. Food coming into the island goes through a strict biosecurity regime to avoid the accidental introduction of bugs. The skins are stripped off onions, and leeks and broccoli are banned because they provide too many hiding places. This may sound extreme but earwigs, for example, have proved tenacious invaders on the Falkland Islands.
People returning from elsewhere on the island have to clean their clothes in the biosecurity area.
And it is not just the smallest invaders that are unwelcome. In the early twentieth century, Norwegian whalers introduced reindeer to the island, as a potential source of meat. They took a long time to establish, but once they did so, their numbers expanded. They became significant enough that there is now a reindeer on the crest of South Georgia. But that is the only place that you will find them. They were affecting the ecology of the plants, and so the decision was made a few years ago to eliminate them – largely by shooting.
The story of South Georgia’s wildlife and in particular of the elimination of the rats is a fascinating one. It may not be over. There has been one definite sighting of a rat which, says Martin, almost certainly came off a ship. While large ships do not pose a hazard, because they cannot dock directly, there is a risk from visiting yachts. And, in particular, if a fishing vessels is ever wrecked on the island then the proverbial rats leaving a sinking ship could pose a very real risk.
Martin and others are concerned that, without even more stringent ongoing measures, the rats can, and indeed will, return. And if this is the case on South Georgia, what price eradication on other, more populous islands? There are many other questions as well. In the case of South Georgia there is an argument that its ecosystem is so special that visitors should not be allowed at all. And it is easy to imagine that, if populations of fur seals continue to recover and therefore tour operators find it ever harder to access the beaches (male fur seals are horribly aggressive) there could even be an argument for a cull. The tour operators work very closely at present with conservationists, but their business in the end is landing tourists.
Martin admits that he respects and even likes rats. In the case of South Georgia, there was a fairly clear cut case for their elimination, but how many other islands could take such a simplistic view? Their ecosystems are more diverse, and it may be hard to argue what the balance could or should be – or avoid the unexpected consequences.
Anybody interested in such issues, or simply in better understanding what was done at South Georgia, will be able to discuss them at the Island Invasives Conference that will be held at the University of Dundee from 10–14 July this year.
For Martin there is a satisfying symmetry to this. There have been two previous conferences, held in New Zealand in 2001 and 2010. He attended the Auckland event in 2010 and was hugely impressed by the expertise of the host nation. ‘The Kiwis decided 20–30 years ago that unless they did something there would be no wildlife left,’ he said. Then the New Zealanders shared their experiences; now it is Martin who is at the forefront. But probably not for long.
At the end of last year, the New Zealand government announced that it intends to eliminate all introduced predators – for which one can read all predators – by the end of 2050. Every rat, stoat and possum will go. It seems that the ambitious project in that funny island in the South Atlantic will have a greater resonance. Next stop UK?