South Georgia's alien invasion
The UK Overseas Territory of South Georgia and the South Sandwich Islands is a spectacular wildlife sanctuary in the Southern Ocean. Thousands of tourists visit by sea each year to enjoy the sight of hundreds of thousands of penguins, seals and seabirds in this glorious setting.
However, South Georgia's seabirds have been savagely depleted by invasive rats and mice, introduced inadvertently from the ships of sealers and whalers in the 19th and 20th centuries. The island's birds nest on the ground or in shallow burrows. They were defenceless against rodents, who decimated their numbers by eating eggs and chicks. Petrel, pintail and prion populations have suffered the greatest damage from the invaders, and the endemic South Georgia pipit is threatened with extinction.
South Georgia Heritage Trust
In 2007, the Trustees of the South Georgia Heritage Trust (SGHT), a small UK-based charity established in 2005, decided to tackle the rodent problem on South Georgia by attempting to eradicate rats and mice from the island, using techniques tried and tested elsewhere, and set about raising the £7.5 million required to carry out the project. It has been estimated that the successful completion of the project could bring some 100 million seabirds back to the island.
The Project Director, Professor Tony Martin, was appointed by SGHT in 2009 to take charge of what would be the largest rodent eradication project ever undertaken anywhere in the world – some seven times larger than any previous project of this kind. Tony Martin immediately set about the complex logistical planning and the acquisition of the equipment (including initially two, and later three, helicopters) required to address this challenging task.
Habitat Restoration for South Georgia
South Georgia has one important feature that makes eradication on such a scale possible. The island is split into discrete areas by wide glaciers. These natural barriers ensure that rodents cannot penetrate land that has been cleared, allowing the project to be completed over a number of years. But climate change had been causing the glaciers to retreat, creating the risk of opening the whole island to invasion by rats. The opportunity to restore the island to its original status as the home of one of the greatest concentrations of seabirds in the world was time limited, and urgent action was required.
Thanks to a small number of extremely generous donors, and the support of the Government of South Georgia and the South Sandwich Islands (GSGSSI), by 2011 SGHT was ready to undertake the first trial phase of fieldwork covering some 12,500 hectares. Four discrete areas of the island were baited using cereal pellets laced with toxin, an irresistible nibble for rats and mice. The bait was specially customised to withstand the South Georgia weather so that the rodents would have access to it for as long as necessary. The bait was spread by Bolkow-105 helicopters with an underslung bucket, creating a swathe of bait and 'painting' the areas where rodents might be present.
All signs indicate that the trial phase of the operation was successful. In the two years that have followed no rat sign has been discovered in the cleared areas, despite extensive monitoring by GSGSSI. In the absence of rats, the breeding success of vulnerable species such as pintail ducks has increased. Ducklings are once again a common sight around King Edward Cove; a positive indication that the baiting work had succeeded.
Following a major fundraising campaign by SGHT to raise the £3 million required, the second and largest phase fieldwork was undertaken from February to May 2013, in some of the most remote and challenging terrain to the north-west of the island. The goal was to bait some 58,000 hectares, an area over five times the size of the trial phase. A team of 25 specialists from around the world was assembled and led once again by Project Director Tony Martin. The aptly named 'Team Rat' travelled from the Falkland Islands to South Georgia in February 2013 on the British Antarctic Survey logistics vessel the RRS Ernest Shackleton. The ship also brought with it three helicopters, 200 tonnes of bait, 700 drums of helicopter fuel, 8 tonnes of food and three 20 foot container-loads of equipment. The helicopters flew the supplies from the ship to depots at 14 different sites along South Georgia's coastline before the team disembarked in late February and, in early March 2013, began the second year of baiting work.
Despite encountering severe weather conditions which stopped the helicopters from flying for days on end, on the 18th of May the last pellet fell on South Georgia's Paryadin Peninsula and Phase 2 was complete. Against the odds, and after almost five months of fieldwork, all the areas planned for 2013 had been baited and the team could go home.
With two successful seasons under its belt, SGHT is confident that it will be possible to raise the further £3 million needed to complete the final phase of work in 2015. With one third of the infested area remaining to be cleared (around 30,000 hectares), the aim of this third phase is to complete the job. If SGHT is successful, the island will once again become the safe haven for wildlife that it was when Captain Cook discovered it back in 1775.
The Trust is very grateful for the support received from the GSGSSI and from all of those who have given donations large and small to the project.