Since 2011, the largest eradication program against invasive species takes place on the Subantarctic island of South Georgia. Thousands of square kilometers had been baited in an attempt to get rid of rats and mice, which had caused massive havoc among the bird population. Now, the program steps into its final phase with surveying the island for traces of any remaining rodents. With any luck, the island soon will be declared rodent-free.

The island, which is 164 km long and 33 km wide, is home to millions of birds, seals and whales. It is a British Overseas Territory and is governed by an appointed Government Officer. Credit: Michael Wenger
The island, which is 164 km long and 33 km wide, is home to millions of birds, seals and whales. It is a British Overseas Territory and is governed by an appointed Government Officer. Credit: Michael Wenger

This Antarctic summer, three dogs, 15 people and three vessels will take part in the fourth phase of the South Georgia Habitat Restoration Project – to date the world’s largest and most ambitious project to eradicate invasive species. The team will seek to confirm the success of a project whose aim is to eradicate rodents from the entire island of South Georgia through aerial baiting, securing this island in the Southern Ocean as a globally important seabird sanctuary for future generations. It is hoped that South Georgia has been rodent-free since 2015 when the third baiting phase was completed, but before work began in 2011 the wildlife of this sub-Antarctic island was increasingly under threat from invasive rodents. These arrived as stowaways on sealing and whaling vessels, and over two centuries had a catastrophic impact on the bird populations, threatening the existence of the South Georgia pipit and South Georgia pintail, both of which are endemic to this UK Overseas Territory.

The rats were a legacy of the whalers and sealer, which once had used the island for their bloody trade. The whalers and sealers went, the rats stayed and dramatically decimated the bird population on the island. Credit: Paula O’Sullivan
The rats were a legacy of the whalers and sealer, which once had used the island for their bloody trade. The whalers and sealers went, the rats stayed and dramatically decimated the bird population on the island. Credit: Paula O’Sullivan

This massive project has been undertaken by a small Scottish charity, the South Georgia Heritage Trust, based in Dundee, which with its USA counterpart Friends of South Georgia Island, raised over £7.5 million to finance the work, securing financial and in-kind support from individuals, foundations, businesses, and government.  Planning and fundraising began in 2007 for three phases of fieldwork (in 2011, 2013 and 2015) by an international team of the world’s leading experts in eradication work, operating in the hostile conditions imposed by South Georgia’s notoriously extreme and fickle weather.  Since the last extensive baiting work in 2015, no sign of rodents has been detected, but a comprehensive survey is required before the island can be declared to be rodent free. So now ‘Team Rat’ as it is known, is returning once more for the fourth and hopefully final phase of this landmark project – to undertake a definitive survey of South Georgia to check that the island is indeed rodent free. The survey will follow international guidelines which suggest that at least two years should elapse following baiting, before an area can finally be declared free of rodents.

Glaciers divide the island and separate the rat populations. Due to the geographical circumstances and for financial reasons, three phases had been necessary to deploy the baits. Credit: South Georgia Heritage Trust
Glaciers divide the island and separate the rat populations. Due to the geographical circumstances and for financial reasons, three phases had been necessary to deploy the baits. Credit: South Georgia Heritage Trust

The survey is now underway, with the Government of South Georgia & the South Sandwich Islands providing support from their logistics and patrol vessel Pharos SG and additional manpower. In line with international best practice the survey will use a combination of detection methods, deploying inert devices, (such as chewsticks, chewboards, peanut butter flavoured wax tags, and tunnel and camera traps), along with specially trained sniffer dogs and their handlers being deployed this month. The survey work should be completed by April 2018. Project Director Dickie Hall said: “The scale of the task is daunting as it is many times greater than any rodent survey previously undertaken anywhere in the world. We are looking at surveying a coastline almost a thousand kilometres long – as well as a land mass of 895 km2. It would be impossible to inspect every square metre of land, so the strategy is to subsample the terrain in such a way as to maximise the chances of detecting any surviving rodents. We have assembled a team of specialists, many with experience of previous expeditions as part of the Habitat Restoration Project, to conduct a thorough survey of the island so we can achieve our aim of declaring it rodent free.” Professor Mike Richardson, a Trustee of The South Georgia Heritage Trust and Chair of the Habitat Restoration Project steering committee said: “This has been an incredibly important project for the wildlife of South Georgia, delivered by a team tackling the often challenging and highly inhospitable climate as well as the remoteness of the location. If no rodents are detected during the survey (which is very much our hope), this final crucial stage should allow us to declare the island rodent free, and in what is no more than a brief moment in the long history of South Georgia, to reverse two centuries of profound human-induced damage to the island's wildlife. Millions of birds will then be able to reclaim their ancestral home and the future of the unique, delicate South Georgia pipit will be secure.”

Next to a multitude of sea birds, South Georgia is home to a few endemic species. The South Georgia pintail, a duck species, is the only carnivorous duck worldwide. Credit: Michael Wenger
Next to a multitude of sea birds, South Georgia is home to a few endemic species. The South Georgia pintail, a duck species, is the only carnivorous duck worldwide. Credit: Michael Wenger

Source: South Georgia Heritage Trust