Eradicating invasive rodents from South Georgia
Watch footage above of the Phase 1 fieldwork showing the preparations in the Falkland Islands, the helicopters flying on and off One Ocean Expeditions’ cruise ship the Marina Svetaeva, and the field team carrying out the work to clear the first four areas of South Georgia of invasive rodents. Thank you to GEO for providing the footage and to Emile Shemilt and Paul Shafi for their help with the footage.
(Note there may be a delay while the footage is downloaded).
|Rats occur throughout almost all of the hospitable, warmer areas of the island – the same habitat required by native wildlife. Mice are only known to occur in one area in the northwest of South Georgia; however, recent reports have raised concerns that they may have been introduced recently into new areas. Based on experience gained around the world, the only feasible way to eradicate all rodents on an island the size of South Georgia is to spread toxic bait by helicopter. This technique has proven to be effective in eradicating rodents from smaller islands and is now widely used. However, this is an immense undertaking – at 100,000 hectares in size, the area of South Georgia being cleared is more than eight times larger than Campbell Island (New Zealand), which at 11,300 hectares is the largest island ever cleared of rodents until now. However, as South Georgia’s rodent population is divided into a number of independent units by the island’s sea-level glaciers, eradication of all rodents is feasible. The eradication operation on South Georgia has required three helicopters, approximately 300 tonnes of rodent bait and three seasons to complete the baiting work.
REMOVING RODENTS FROM SOUTH GEORGIA
A rat eating the speciallydeveloped bait which is unattractive to birds
One of three Bolkow-105 helicopters purchased that was used to spread the bait
Monitoring during operations
Every precaution is being taken to minimise the risk to native and endemic fauna. The majority of the birds on South Georgia are seabirds that eat only marine prey; therefore, it is unlikely that they will consume the poison. Scavengers, such as skuas and giant petrels, could ingest enough poison through eating dead or dying rats to become ill themselves. However, rodents that take the bait become photophobic (scared of light) and consequently most die in their burrows, where they are inaccessible. Therefore, death of scavengers due to secondary poisoning is likely to be relatively rare. Streams and drinking water will not be affected because brodifacoum is not soluble in water. A few birds, such as ducks and gulls, might be tempted to eat the pellets directly. The habitat restoration team carefully monitor each season’s operation, and are ready to modify or stop work altogether if any wildlife looks likely to suffer long-term, population-level damage as a consequence of the Project.
Experience from other rodent eradication operations has demonstrated that the bait pellets used on South Georgia are extremely attractive to rodents; they will eat them in preference to their natural food. The active ingredient in the rodent bait pellets is called brodifacoum. It is an anti-coagulant, which causes the rodent to die of internal bleeding and organ failure. All rodent baits that can offer 100% success act in a similar way to brodifacoum – none offer a more humane solution to this problem. Suffering by any animal is deeply regrettable, but unless rodents are removed from South Georgia, every year thousands, perhaps millions, of young birds will be eaten alive by rats. The death of one rat now will prevent the killing of many nestlings over time, and probably save one bird, the , from extinction. On balance, most people would agree that eradicating rodents from South Georgia is justifiable, indeed necessary.
The team also works to ensure that the operations using helicopters do not scare the wildlife. Helicopters approach any bird colonies slowly at a high enough altitude to minimise impact and only go near them when actually spreading bait in their vicinity. Seals are more tolerant than birds to disturbance, but every effort has been taken to minimise their stress wherever possible. In all cases, observers on the ground monitors for any impact caused by the helicopters and procedures modified if needed.
Phase 2 complete!
Years of planning and fundraising went into preparing for the first phase of the Project – the eradication of rodents from areas around and adjacent to King Edward Point and Grytviken, from a rocky promontory on the western side of Mercer Bay (green zone on map, below), and from the recently infested Saddle Island. While the Phase 1 area was approximately one tenth of the total infested area of South Georgia, it was substantially larger than Campbell Island, the largest island cleared before the South Georgia project.
With plans for Phase 1 complete, SGHT assembled its habitat restoration team, ‘Team Rat’, which brought together experts in invasive species eradication as well as team members with extensive experience of working in South Georgia. Permission was granted by the Government for South Georgia and the South Sandwich Islands (GSGSSI) to begin fieldwork in February/March 2011. The much larger second Phase was then carried out with a team of 25 from February to May 2013. The operational work was a complete success with the team enduring some of the harshest weather on South Georgia for a decade. If the area baited (65% of the infested parts of the island) has indeed been completely cleared of rodents, the island’s birds will be able to nest safely for the first time in over two centuries. Signs are good that birds are returning to the areas cleared in Phase 1, and two years on there is no sign of rats.
Phase 1 cost about £1.6 million, Phase 2 (which cleared an area five times the size of Phase 1) cost £3 million. SGHT is grateful to all those donors who contributed to funding for the first two phases of the SGHT Habitat Restoration Project.
Phase 3 complete!
The final bait pellet of the third and final baiting phase of the Habitat RestorationProject was sown on Monday March 23rd 2015 .
South Georgia may now be rodent free for the first time in centuries thanks to all our donors so far.
Howard Pearce. Chairman of SGHT said this on the 25th June 2015
“We have finished the baiting, we hope that we have succeeded and we hope there are now no live rats on South Georgia. The impact of that on South Georgia is going to be enormous – we’re going to be seeing, we are indeed already seeing birds returning to areas where they have not been seen in living memory.
Over the decades and the centuries we will be witnessing a huge increase in the bird population of South Georgia. Scientists say we could be talking in terms of up to 100 million more birds on the island. That’s an amazing figure.
So we have completed this crucial baiting phase but we do now need to be confident as to whether we have succeeded or not. Over the next two to three years we are going to have to undertake some intensive monitoring of the work we have done on South Georgia. So that we can be confident that we have succeeded or we can identify areas where we still have more work to do.
And it is inevitably going to cost some money. We probably have to raise about half a million pounds in order to pay for that essential work.”
“We’ve been learning a lot of detailed lessons in the field and we want to share those lessons with others who might be thinking of doing something similar. It does demonstrate what can be done if you get the right team of people together and you have the right vision and the right determination.”
The future of the SGHT Habitat Restoration Project.
Professor Tony Martin, Project Director, describing the monitoring phase of the project..
“The rule of thumb internationally is to investigate two years after you finish baiting and if you don’t find any rodent sign you say that’s it – job done. We’re going to leave it a little bit more than that and in fact in the case of phase 2 it’ll be four and a half years, because it is such a vast area.
No one has tried to look for rodents over a place 100 miles long, with mountains 3,000 meters high. …but we have to do it at some stage and so the end of 2017, beginning of 2018 will be the best time to do it we believe. We’ll go there with a team of people with chew sticks and camera traps and various other devices and if no rodent sign is found then South Georgia will be declared free.”
We now urgently require funding for the monitoring phase of the project, to verify the eradication of all rodents from the island of South Georgia.
Ultimately, the whole of South Georgia would be overrun by rats and mice unless every single rodent has been eradicated. Our objective is clear – we must remove every rodent from every piece of land on South Georgia, and leave it rodent-free for generations to come.
Your support for SGHT can directly help return millions of seabirds to South Georgia, and restore the island’s native ecology. Join the donors who are helping to make this happen.
The arrival of rats on South Georgia as stowaways on sealer and whaler ships had a catastrophic effect on the island’s bird populations. The SGHT Habitat Restoration Project aim is to have removed every rodent from every piece of land on South Georgia by 2015, helping to restore its native ecology and restore millions of seabirds to the island. We hope we have suceeded and we must complete the monitoring phase to declare South Georgia free.<More information about South Georgia’s endemic and native species that are threatened by invasive rodents>
Book Review: Reclaiming South Georgia
Tony Martin’s book “Reclaiming South Georgia: the defeat of furry invaders on a sub-Antartctic island” is reviewed by Martin Heubeck in British Birds magazine September 2016.
Tony’s book tells the story of the Habitat Restoration project which aimed to eradicate rodents from the island.
Click here for the pdf version of the review.