Conservationists unleash rodent detection dogs in final phase of world’s largest rodent eradication

Three small dogs are at the centre of the final phase of the world’s largest project to eradicate invasive species.  Terriers Wai, Will and Ahu have joined a team of 16 humans deployed by the South Georgia Heritage Trust (SGHT) to conduct a monitoring survey of the British Overseas Territory of South Georgia for signs of rodents. Thanks to significant funding from Friends of South Georgia Island (FOSGI) and with personnel and logistical support from the Government of South Georgia & the South Sandwich Islands, the Trust has embarked on what is hopefully the final phase of its ambitious £7.5 million conservation project to restore the island’s native bird populations.

The terriers are specially trained to detect rodents, invasive predators which arrived on South Georgia as stowaways on sealing and whaling vessels from the 18th century onwards.  As the native wildlife evolved in the absence of rats and mice, the introduced rodent population wreaked havoc on the island’s ground-nesting and burrowing birds, in particular threatening the existence of two endemic species; the South Georgia pipit and South Georgia pintail.

Scottish-based charity SGHT started the first phase of baiting of the Habitat Restoration Project – to date the world’s largest project to eradicate invasive species – in 2011, in a bid to reverse two centuries of human-induced damage to the island’s wildlife and allow millions of birds to flourish and reclaim their ancestral home.  Since the last extensive phase of baiting work in 2015, no sign of rodents has been detected, and many bird species are already showing signs of recovery, but a comprehensive survey was required before the island could officially be declared rodent-free.

With its complex terrain of glaciers, deep crevasses, dramatic mountains, and storm-swept beaches, as well as unpredictable weather conditions, the sub-Antarctic island of South Georgia is one of the most remote and inhospitable places on Earth.  In an incredible feat of endurance and teamwork, reminiscent of Sir Ernest Shackleton’s epic crossing of the island just over a hundred years ago, the dogs and their two female handlers, Miriam Ritchie and Jane Tansell, have so far walked a total of 1415km, with the dogs covering a total of 2124km, searching for signs of rats.  The distance will continue to mount as the monitoring survey progresses, but they have already surpassed the equivalent of the trek from Land’s End to John O’Groats, which at 1407km covers the whole length of the island of Great Britain.

Like Shackleton before them, Ritchie and Tansell are unfazed by the scale of the task. This involves sub-sampling a coastline almost a thousand kilometres long and a vegetated land mass of 895 km2 .  Ritchie explains: “The size of the survey area is vast, and the dogs stay close to us, but of course they can detect smells from many metres away, so they help increase the range of what is actually covered on foot.  They can also get to areas that are inaccessible to humans, such as nooks and crannies in the landscape, or within the former whaling stations.”

Ritchie and her colleague Tansell are extremely experienced dog handlers from New Zealand and are used to working in remote environments.  Tansell has a veterinary nursing qualification and both of the women have worked as handlers with the New Zealand Conservation Department and have trained a number of detection dogs, including brothers Wai and Will, and their cousin Ahu.

Ritchie says: “All three of the dogs have a lovely, calm temperament and are very quiet around birds.  Their training is as much about ignoring other smells, as it is about recognising rodent odour.  South Georgia is famous for its vast penguin colonies and thousands of seals, and the dogs’ noses are filled with the intense smells of these animals the whole time. They have to ignore all this and simply focus on, and react to, the one extremely weak smell of rodents.”

The SGHT field team, dubbed ’Team Rat’, started the monitoring survey in October 2017, and the handlers and their dogs joined in December 2017.  The team has been supported by three vessels, including the MV Hans Hansson, which has been chartered by SGHT.  The Trust has been particularly indebted to the Government of South Georgia & the South Sandwich Islands for the support of its patrol vessel Pharos SG, and to Thies Matzen and Kicki Ericson, the owners of the expedition yacht Wanderer III. Both have provided invaluable assistance.

In line with international best practice, the team have been using a combination of detection methods during the survey, so in addition to the detector dogs, they have also used special inert devices, such as chewsticks and camera traps.  Over a thousand such devices have been deployed as part of the survey, which the field team will complete by the end of April.

SGHT plans to announce the outcome of the monitoring survey at a press conference in London in early May.

Dickie Hall, SGHT Project Director, says: “Following the baiting operation, there has been a remarkable and dramatic increase in the number and distribution of many bird species. The song of South Georgia pipits, the most southerly songbird, is now louder than the bark of elephant seals!  However, this monitoring survey is essential before we can confidently declare South Georgia free of rodents.

“This survey has been the culmination of 10 years of planning and months of challenging field work over four sub-Antarctic seasons by an international team, led by SGHT. We are all on tenterhooks, waiting for the results as the survey nears completion.  There is no room for error – we have to have eliminated every single last rodent if we are to save many vulnerable bird species like the South Georgia pipit from extinction.”

History

  • For further information visit: www.sght.org
  • The South Georgia Heritage Trust was founded in 2005 to preserve the sub-Antarctic island’s natural, human and cultural heritage; raise awareness of the island’s endangered flora and fauna through research and public engagement; manage practical conservation programmes to protect native species. Its associate organisation, Friends of South Georgia Island (FOSGI), is a USA non-profit with 501(c)(3) dedicated to raising funds for South Georgia and has been extremely successful in financially supporting the Habitat Restoration Project.
  • South Georgia is one of the world’s last great wilderness areas and amongst the wildlife on the island are 95% of the world’s Antarctic fur seals and half the world’s elephant seals. Four species of penguin nest on the island, including King Penguins with around 400,000 breeding pairs. The island’s birdlife includes numerous species of albatrosses, prions, skua, terns, sheathbills and petrels, as well as the endemic South Georgia Pipit, and the South Georgia Pintail. But although the wildlife remains impressive, it is but a shadow of what Captain Cook encountered when he discovered and named South Georgia in 1775. Rats and mice, arriving in the ships of sealers and whalers, have spread over much of the island, predating on the eggs and chicks of many of the native birds. The aim of SGHT’s Habitat Restoration Project is to eradicate these invasive rodents and allow millions of birds to reclaim their ancestral home.
  • SGHT has conducted three phases of baiting, including aerial baiting by three helicopters and hand baiting inside former whaling stations.
  • The trial phase (Phase 1) of the Habitat Restoration Project was successfully completed in March 2011 – in just 28 days – and Phase 1 alone made this project the largest island rodent eradication operation ever undertaken in the world.
  • Phase 2, the largest single part of the project, was undertaken in 2013 and completed after three and a half months in the field, despite extraordinarily hostile weather. SGHT conducted a monitoring survey of the Phase 2 area in March/April 2014, which reported no signs of rodents.
  • With the completion of Phase 3 in March 2015 Team Rat had successfully baited every nook and cranny of South Georgia that might be infested by rodents, an area of over 1000km2 of land.
  • SGHT and its US-based counterpart, Friends of South Georgia Island (FOSGI), have raised over £7.5 million to finance the Habitat Restoration Project, securing financial and in-kind support from numerous individuals, foundations, businesses, and government, to which we are extremely grateful.
  • SGHT has worked closely with the University of Dundee Centre for Remote Environments (CRE), British Antarctic Survey (BAS), and the Government of South Georgia & the South Sandwich Islands (GSGSSI).  Additional support has been received from various Antarctic tour operators in transporting personnel and equipment, with Iridium Satellite Communications and Ship to Shore Traveller providing generous in-kind support for Phase 4.
  • South Georgia is a UK Overseas Territory administered by the Government of South Georgia & the South Sandwich Islands.