Gough Island, part of the UK Overseas Territory of Tristan da Cunha located in the remote South Atlantic, is considered one of the most important seabird islands on the planet. A World Heritage Site, this small spec in the ocean is known to support millions of breeding seabirds, including the iconic Critically Endangered Tristan albatross. Sadly, non-native invasive mice were introduced by passing sealers during the 1800s. Today, we know the invasive mice kill over 600,000 chicks each and every year. If nothing is done, we will lose some of these iconic seafarers forever.
The RSPB and our partners are working hard to restore Gough Island, as part of the Gough Island Restoration Programme. As the RSPB prepares to restore Gough Island, Keith Springer, our eradication expert, embarks on his first visit to the island. Here is his story so far.
If you would like to learn more about the Gough Island Restoration Programme, please follow this link.
If you would like to support our efforts to save this important seabird island and prevent the deaths of over 600,000 seabird chicks a year, please go to our donation page.
If you missed the first two parts of this blog series, they can be found here: Part 1 & Part 2.
As we sail east toward Cape Town, there’s now time to reflect on the two weeks spent on Gough Island, and think through what I’ve seen on the island and translate that into planning for a team to spend the winter there in 2019 in an attempt to eradicate mice.
Evidence gathered over several years has lead to alarming declines in the breeding productivity of most seabird species on Gough Island. For some species, like the Tristan albatross, this impact has been readily visible – the large chicks with open wounds lying dead on their nest pedestals tells that story. More invisible has been the impact on burrow-nesting seabirds. The predation on eggs and chicks of most species that breed in burrows was suspected but until relatively recently was hard to prove, because this happens underground at the end of a long burrow. It was only the use of fixed cameras in the nest chamber of some burrows that the extent of mice predation underground was realised to be equal to, if not worse than what was happening above ground. Breeding success for some of these species varies between zero and 15% and it is not hard to see that once the current generation of breeding birds die, there will be few juveniles left to replace them, placing the populations in dire straits indeed. There is simply no other long-tem alternative to help these species other than to attempt the removal of every mouse on Gough Island.
From an operational perspective, I’m happy to report some good news. Nothing that I saw on Gough Island would be a show-stopper for the mouse eradication project. There is no doubt in my mind that there will be challenges along the way but planning will help overcome these. The ‘how-to’ of eradicating rodents from islands is quite well established and an operational plan has been drafted for this project. The fact that some of these challenges will stretch available resources is however clear. The project must keep a large team of people plus helicopters at Gough for about 2-3 months, and charter a ship to deliver us there and pick us up. Helicopters and ships don’t come cheap, and nor do experienced teams to make this type of programme happen seamlessly and productively. But that is a fund-raising challenge, and my focus in the course of this visit was to look at more of the on-island issues.
Weather will undoubtedly be one of the challenges that are outside our control. I got a glimpse of how weather conditions on Gough can compromise flying time. When I first got to the island, I jumped at the chance to join a helicopter flight intending to drop gear off at a high point. This was an opportunity for me to get an impression of the interior of the island and check out a couple of the higher points as potential VHF radio repeater sites. An island-wide radio communications will be an essential requirement both for operational efficiency and for safety. Unfortunately, cloud descended and we had to cancel the inland leg of this planned flight. This highlights why we need to plan to be on island and ready to go at the start of our operational window.
I spent some time inspecting the helipad and measuring the existing set up. For our operation we’ll use this steel helipad and an old wooden area around. This wooden area will be a useful operating platform for machinery and storage of bait. It’s not that robust though, so would need strengthening before we could put bait storage pods on it, and use it as an operating area, possibly with machinery.
The existing helipad is also probably too small for the number of helicopters likely to be operating on the island for the aerial baiting work. The surrounding terrain is quite uneven and the vegetation variable, with patches of Phyllica scrub, bog fern (Blechnum) and tussock predominating. I needed to find alternative areas that were still accessible from the helipad or walkway where we could build additional helipads. We may also need to build a hangar where it is fairly flat, which will require a space around 30 metres by 15 metres –not easy to find around the base. We’re also anticipating the need to build two aviaries to hold captive populations of endemic moorhens and buntings during the baiting operation. So some time was spent with Chris Taylor from the Gough 61 team scrambling through the vegetation and identifying and recording possible sites.
The final question for me was to establish whether a large group of people would fit into the existing base for the winter months in 2019, along with all the equipment and supplies to support the operation. In short, the answer is ‘hopefully’! Depending on the size team we bring in, there might just be room for everyone, although the existing dining and recreational areas are not designed for a base population around 40, which is what can be expected for the period during the baiting.
It wasn’t all operational planning work while I was on island. During my second week on Gough, we saw an amazing sight one evening as thousands of Great shearwaters returned to the island after spending the winter away. The sky off Cavern Head and directly offshore from the base was filled with fluttering, wheeling shapes as the birds congregated offshore in the gathering dusk. Another great sight was on a windy day with the wind coming from the south-east and hitting the cliff below the base, then being forced upwards. The sooty albatross obviously knew this spot provided great wind dynamics and would either sail along parallel to the cliff edge, riding the wind current, or swoop low over the edge to hit the full blast of the updraft, and try and maintain position as long as they could before stalling away downward out of the updraft, only to come around time and again for another go.
Great shearwaters off Cavern Head. Photo credit: Chris Taylor
We left Gough on a sunny clear morning and finally got a chance to see the higher parts of the island which were standing clear in the sunshine. After a day off Inaccessible Island while teams were ashore counting penguins, and three days at Tristan da Cunha, we departed for Cape Town.
All in all it has been a very informative trip and one which for me both answered some questions about base infrastructure and facilities, but also raised others as to how we go about planning to remove mice from Gough Island. Once fundraising has got to the point where the project is given the green light to proceed, then planning can begin in earnest to resolve some of these questions.Gough