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Results Forum News 35 article: Eradication work on Gough continues Purpose To prepare for the eradication of mice and move towards the eradication of invasive Sagina procumbens on Gough Island. Analysis of the problem Gough Island, part of the Tristan da Cunha group, is one of the UKOT's most important sites for biodiversity, as recognised by the island s status as a natural World Heritage Site (one of two in the UK OT's), Site for Zero Extinction (one of seven in the UK OT's) and an Endemic Bird Area, and recently recognised Ramsar site. Supporting two endemic landbird species and 20 species of breeding seabird totalling tens-of-millions of individuals, Gough is often described as one of the world's most important seabird islands. Invasive alien species are the main threat to the biodiversity of the UKOT's and the key threat to the biodiversity of Gough Island is the presence of invasive House Mice and the invasive weed Procumbent Pearlwort (Sagina procumbens). House Mice were first recognised as a conservation problem in 2000/01, when it was discovered that the species was a major predator of winter-breeding seabirds on Gough Island. Follow-up research has established that mice are responsible for unsustainable breeding failures of the Tristan Albatross and Atlantic Petrel - both effectively endemic to the island - in all years studied. During 2008, the Tristan albatross population experienced its worst ever year of mice predation, with just 14% of incubating birds producing a fledged chick. We estimate that half a million Atlantic Petrel chicks are killed by mice each winter. The endemic Gough Bunting is also affected by mice, both directly from predation of eggs and chicks and potentially also by competition for food in the winter. Over the last 20-years the Gough Bunting population has halved. The conservation status of both the Tristan Albatross and Gough Bunting has recently been upgraded to Critically Endangered because of the impact of mice, and additionally for the Tristan albatross, long-line mortality at-sea. Other winter-breeding seabirds including Great-winged Petrels and the Near Threatened Grey Petrel are also likely to be heavily impacted by mice though there have never been sufficient resources available to confirm this. The invasive plant Sagina procumbens is a native of northern Europe that has been very successful in colonising and spreading to sub-Antarctic islands throughout the world. Sagina has colonised both Marion and Prince Edward Island (South Africa) and Tristan da Cunha. On Marion and Prince Edward islands (both at similar latitude to Gough in the Indian Ocean) the spread of Sagina has caused major change in the floral composition of the island s bogs and feldmark vegetation, and Sagina now forms a mono-specific mat of vegetation to the complete exclusion of native plants over large areas of both islands. The long-term impact of Sagina on Marion and Prince Edward are unknown, however it is likely there will be major changes in invertebrate communities and nutrient cycling (especially peat formation). Preventing such a scenario occurring on Gough Island is a vital priority in order to protect the unique upland vegetation communities that are present. Project context During recent years, the technology and knowledge to eradicate invasive alien rodents has been developed and applied to island systems around the world, but particularly in the Southern Hemisphere. This has resulted in spectacular biodiversity recovery and ecosystem restoration at sites such as Campbell and Raoul Islands (both New Zealand) and many others. Ambitious multi-species island eradication projects are now being developed for many large islands off New Zealand, as well as for Lord Howe and Macquarie islands (Australia). These new eradication efforts are increasingly targeting mice (e.g. planned operations at Macquarie and Lord Howe islands, and recently completed operations at Bench and Kaikoura islands in New Zealand [bait drops in July 2008]) as well as rats and other invasive species (particularly rabbits). Among the UKOT's, the major sites on which rodents are thought to have devastated globally important biodiversity, and where eradication is a plausible option (due to lack of a large human population) are Tristan da Cunha, Gough, and Henderson islands. The Management Plan for the Gough Island Wildlife Reserve has as a long term goal, the removal of mice from Gough Island, and the workshop report Assessing Management Options for the introduced rodents of Tristan da Cunha (funded under TDC203) states that the biodiversity gains from a mouse eradication on Gough would be immense. The RSPB research report A review of the impacts of introduced rodents on the islands of Tristan and Gough (funded under TDC203) concludes that if house mice impacts are removed from Gough then a recovery of affected bird populations is expected, leading to an improved conservation status, as well as maintenance of plant and invertebrate communities. The disastrous impact of invasive plant species on islands has long been recognised, however, it is only in recent years that conservationists have attempted eradication of these plants, as well as greatly increasing efforts to prevent the introduction of further species. OTEP projects TDC201 and TDC403 and AG 5108 have begun work on the eradication and control of invasive plants on Gough and Tristan da Cunha. Work on Inaccessible and Nightingale islands in 2004 and 2007 (supported by TDC002 and TDC403) has been successful in removing invasive New Zealand Flax (Phormium tenax) from a large area of tussock and coastal cliffs. The invasive grass Arrhenatherum elatius was eradicated from around the weather base at Gough Island during 2005/06. Control operations are underway on Tristan to remove loganberry (Rubus loganobaccus) from Sandy Point (TDC404). Support from the RSPB managed South Atlantic Invasive Species (SAIS) Project is helping Tristan to increase quarantine facilities to prevent the introduction and spread of further invasive plant species between islands. Complementary initiatives, and other relevant programmes/projects RSPB is the UK partner of BirdLife International and is in contact with BirdLife partners and conservation organisations worldwide in connection with island eradication operations. Very ambitious initiatives to eradicate mice from sub-Antarctic/cool temperate islands are being developed by government bodies of South Africa, Australia and New Zealand. This research compliments the RSPB-managed South Atlantic Invasive Species Project (SAIS) that aims to build capacity with the South Atlantic OT's to undertake and manage the risks posed by invasive species, including both invasive rodents and invasive plants. This project supports key priorities that SAIS has determined for Tristan and Gough, but does not have the resources to implement. The RSPB is also involved (with OTEP support) in the final stages of planning for an eradication of rodents from Henderson Island (Pitcairn): a parallel attempt to more towards the restoration of the other UK natural World Heritage Site in the Overseas Territories. Co-ordination with other agencies working in the country By virtue of the current and past OTEP projects (TDC 201, 203, 302, 403 & AG 5108), it has been possible to keep a dialogue open with the Tristan da Cunha Agriculture and Natural Resource Department and Tristan's Island Council and Chief Islander(s). Close collaboration has also existed with the University of Cape Town through coordinated work programmes on Gough Island and Tristan's biodiversity. The rodent feasibility assessment for Tristan da Cunha and Gough has involved working with rodent eradication experts from New Zealand (the country that leads the world in successful rodent operations), putting this project in contact with leading experts and organisations involved with eradication of rodents. These stakeholders have been able to comment on successive drafts of the feasibility study, and thus on the work programme of this proposal. The RSPB has recently employed a member of staff to work on Tristan da Cunha during 2009, which will help facilitate close co-operation with ANRD. How the new activities build on the previous ones This project is a direct follow-on from TDC203, TDC403 and OTEP AG 5108. The proposal has emerged from the need to continue the Sagina eradication, now that the newly developed techniques are showing encouraging signs of success. Continuing this programme of work without a break or gap in coverage is essential in order to eradicate Sagina: a year's break will put this project back to square one and may potentially allow the plant to escape from the current infected area. It is vital to recall that with invasive species, action in the early stages of spread is massively more cost-effective than delaying, and that evidence from other islands suggests that Sagina could become entirely and irreversibly dominant over great swathes of Gough. It is precisely because Sagina is currently a highly localised plant on Gough, that a sustained, intensive eradication effort now is a cost-effective activity. The Feasibility Study for mouse eradication on Gough (funded by OTEP project TDC 203), is positive about the prospects for a mouse eradication from Gough Island, however this study has highlighted the need to address threats to non-target species, in particular the Gough Moorhen and Gough Bunting. The feasibility report states that The whole endemic Vulnerable Gough moorhen population is likely to be at risk both directly by eating the baits and certainly from secondary poisoning by eating dead mice. Options to manage this risk are to hold birds in cages on Gough Island, or on Tristan da Cunha for the duration of the risk. The whole Gough bunting population is also at direct (but lesser) risk. RSPB is committed to removing these barriers, and reaching a point where a mouse eradication can be planned and funded. The current OTEP (AG 5108) begins this process, but ends in 2009; this proposal is to continue along this route. Monitoring and ecological studies of birds on Gough builds on research and monitoring work established in 2000 and earlier, and is crucial for determining population trends, to quantify the conservation gains of a mouse eradication, and to learn lessons from an eradication that can be applied to other projects and similar invasive problems elsewhere in the Overseas Territories. Ouputs Solutions to potential risks to non-target endemic birds arising from mouse eradication programme on Gough are defined and resolved. Baseline biodiversity data are obtained and analysed in advance of a mouse eradication programme on Gough. Sagina procumbens is effectively controlled, with substantial progress and estimated end-point for the complete eradication. Main Activities - Project managed in an effective and participatory manner
Existing email contact continues with the Tristan Biodiversity Advisory Group to be used as a means of regularly involving stakeholders. Contact will also be continued with plant eradication (Dr Niek Gremman), avian husbandry (Zoological Society of London and Royal Zoological Society of Scotland) and rodent eradication experts (New Zealand Department of Conservation staff and Australian scientists leading the Macquarie and Lord Howe island eradications). The project will work with the Tristan Agriculture and Natural Resource Department (ANRD) in the planning and actions for the Sagina eradication and protection measures for the Gough bunting and Gough moorhen, making sure where possible to engage the Tristan Darwin Team in the work. - Logistical arrangements made for safe deployment of fieldworkers and research plan on Gough Island
Berths secured with South African National Antarctic Programme (SANAP) for personnel and equipment to Gough during 2009, 2010 and 2001 relief voyages, and contact made with Ovenstones regarding berths from Gough to Tristan for ANRD Darwin Team members. Fieldwork team with required set of skills (camp management, rope-access qualifications for cliff work on Sagina, first aid, bird husbandry, bird research and monitoring) recruited. Necessary training given to fieldworkers prior to departure, especially rope-access training if required (preferably an Industrial Rope Access Training Award (IRATA or RAFAA level 1 or above, or equivalent). Coordination with Tristan ANRD over availability of suitably trained (rope-skills) members of the Darwin Team to join the team during the September to December period. Support arranged through the South African National Antarctic Programme and operating helicopter company during the relief voyages utilising the S.A. Agulhas supply ship and its logistical capacities. Bio-security measures put in place to ensure all equipment and fieldworkers take the strictest precautions to prevent new introductions. - Fieldwork teams deployed on Gough Island for three consecutive field seasons from September 2009 to February 2012
Two experienced fieldworkers to be on Gough for three consecutive seasons from September 2009 to October 2010, September 2010 to October 2011, and September 2011 to February 2012. To be joined by two fieldworkers from Tristan da Cunha ANRD in each year to work on Gough from September to December/January, and/or during the S.A. Agulhas relief voyage. Project managers and scientific advisors from the RSPB/UCT and Rope Access Specialists (IRATA/RAFAA level 2 or 3) will be in the field during the S.A. Agulhas relief voyages during September and October of each year. - Captive husbandry trials for the Critically Endangered Gough Bunting and Endangered Gough Moorhen
In order to safeguard Gough's two endemic landbird species - the Gough Bunting and Gough Moorhen - captive husbandry trials will be undertaken to determine the requirements of both species in captivity and the optimal approach to this task during an eradication operation. Trials and activities will include determining methods of capture and estimated time-scales required for capture of sufficient birds, diet and cage requirements, behaviour in captivity (including assessing numbers and sex of birds that can be kept together), construction of cages and ability to mouse proof cages and secure them from poison bait dropped during an eradication. - Trials for species at risk of primary and secondary poisoning
Assessing the risk of Gough Moorhens and Gough Buntings will be undertaken through a capture mark-recapture of individuals that have access to fluorescent pyridine dyed non-toxic baits, in order to ascertain the proportion of individuals that have ingested bait and the risk to the species. Further trials will determine the likely risk of secondary poisoning (from consuming poisoned mice) through a radio-tracking study of 30 mice that have ingested toxic bait. This will allow us to understand the behaviour of mice following toxic-dosing and their potential availability to none-target species (rats usually remain below ground in their nests following poisoning, and are inaccessible to avian scavengers, but it is not known whether House Mice show the same behaviour). As the mice are radio-tagged, regular tracking can ensure no actual cases of secondary poisoning occur during the research. - Continue containment and eradication of Sagina
The introduced plant Sagina procumbens (Procumbent Pearlwort) is restricted to 200m of coastal cliffs close to the weather base. Control operations since 1999 have been successful in restricting the spread of the Sagina, however some years of low effort and a lack of necessary expertise to safely access vertical cliffs has prevented its eradication. Efforts have been greatly increased since September 2006, with 2-3 teams undertaking control during spring, summer and winter periods. A new approach to the eradication of Sagina has been taken since September 2008 (initiated under OTEP AG 5108), with a more vigorous scorched earth approach, stripping the soil in infected areas down to bed-rock, followed by treatment with high-pressure hosing with near-boiling water and/or salt-water. Early indications from this new approach are encouraging, with stripped areas showing very few germinating plants (only present in rock cracks where traces of soil and seeds remain) and salt-water trials demonstrating that this technique kills both adult plants and germinating seedlings. Having started this new approach, it is essential to continue it in as vigorous a manner as possible in order to succeed in a final eradication of Sagina in the near future. By the end of this project we will have: - Stripped the entire Sagina infected area down to bed-rock
- Determined the best approach to removing seeds/soil from remaining areas (e.g. herbicides, hot water or salt water high-pressure hosing, concreting over)
- Established a robust method for monitoring Sagina
- Quantified the effectiveness of the new measures at removing Sagina and produced an estimated end-point for the plant s complete eradication.
This work will be undertaken by trained and qualified rope-access workers, and following a rope-access course planned for Tristan in August 2009, members of the Tristan ANRD Darwin Team will join the team each year, to remain on island for 3-4 months during the spring and summer when the bulk of the control measures will be undertaken. - Monitoring bird populations and establishing baseline data on Gough's wildlife prior to an eradication
Methods for the long-term monitoring of Gough Island bird populations were established in 2000-2001 and repeat counts 2003/04, 2005/06 and 2008/09, has enabled new population estimates and trends to be provided for many species. Demographic and ecological studies have also been established of the Tristan Albatross, Atlantic Petrel, Great Shearwater and Gough Bunting, which have determined the impact of mice on these species. This project will continue these monitoring and demographic studies, which will be vital in determining the benefits (and any potential negative impacts) of a mouse eradication operation. This project will also extend this research and monitoring to establish baseline data for the following wildlife: - Determine breeding success and levels of mice predation on the winter-breeding Great-winged Petrel (Pterodroma macroptera), Grey Petrel (Procellaria cinerea), and Kerguelen Petrel (Lugensa brevirostris)
- Estimates of the current population size of Great-winged, Grey and Kerguelen Petrels
- Establishing a baseline index of abundance for numbers of nocturnal burrowing petrels (especially the small storm and diving-petrels) through repeat monthly spot-lighting to quantify numbers and species present
- Quantify numbers, size and species diversity of macro-invertebrates through pit-fall trapping and soil-core samples in key habitats
- Establish vegetation and photographic plots for repeat monitoring
The conservation evidence (positive or negative) provided by this monitoring will be of great importance for global eradication experts as well as for measuring the benefits of a mouse eradication on the ecology of Gough Island. - Analysis and reporting
Reports on activities 4 to 7 will be produced by fieldworkers and the project manager, and circulated to stakeholders before formal publication as RSPB Research Reports, peer-reviewed scientific papers, and posted on RSPB and Tristan da Cunha websites. Reports on activities 4 and 5 will subsequently be used by an international eradication expert to produce a full operational plan for the eradication of mice.
Stakeholders Tristan da Cunha government and community The Conservation Officer and Head of the Agriculture and Natural Resource Department of Tristan da Cunha have been consulted about the project proposal and support its submission. They have also been partners of TDC203, TDC403 and OTEP AG 5108. The South African National Antarctic Programme (SANAP) and Department of Environmental Affairs and Tourism (DEAT) SANAP and DEAT are responsible for the running of the weather base on Gough Island and the over wintering teams that are placed on Gough. The director and key managers at SANAP are very supportive of plans to eradicate mice and Sagina from Gough Island and have been informed of this application. SANAP have a long-term interest in the eradication of mice from Gough Island, as they want to initiate a complimentary project to eradicate mice from Marion Island, and SANAP has already expressed its support at assisting with the mice eradication programme on Gough. Royal Zoological Society of Scotland (RZSS) & the Zoological Society of London (ZSL) The RSPB has a good working relationship with colleagues and ZSL and RZSS and the latter organisation has recently supported the Tristan Conservation Officer's work programme. Colleagues at both organisations have been consulted over providing advice on the husbandry and captive care of Gough Buntings and Gough Moorhens and are keen to advise. Critical Assumptions Risk 1: Accidents or illness to staff on Gough Island could have serious consequences for personnel and the fieldwork programme
Probability: Low
Impact: High
Management: Prior medical examinations; cooperation with Gough Island weather base (where a medic is permanently stationed); comprehensive medical supplies; Insurance for evacuation, backup communication equipment. Project manager's many years previous experience at the site will inform safety planning. Risk 2: Failure to acquire suitable expertise and equipment for fieldwork
Probability: Low
Impact: High
Management: Contact with relevant experts on bird husbandry has already been made and ordering any specialist equipment will take place well ahead of the project. Project manager's many years previous experience at the site will inform logistic plans. Risk 3: Berth space is not available to send field teams to Gough Island
Probability: Low
Impact: High
Management: SANAP have already been contacted to request that fieldworkers be included in their plans for the over wintering teams on Gough. As part of the SANAP team, berths will be assured. SANAP have taken an active interest in the mouse eradication, both for Gough and for South Africa's Marion Island, hence their verbal support for this project is very likely to ensure fieldworkers will be included in subsequent teams. Ovenstones and the Tristan Administrator will be alerted as soon as possible, should there be a requirement for berth spaces outside the S.A. Agulhas or for berths from Gough to Tristan for members of the ANRD Darwin Team. Risk 4: Effective logistical support on the island is not available
Probability: Low because the project will fall under the SANAP programme where support will be given
Impact: High
Management: All potential steps will be taken in advance to ensure SANAP gives sufficient priority to this work to ensure it will occur during the key research periods, with necessary helicopter and small boat support during takeover periods, and support of the team throughout the year. Wider Significance The eradication of invasive mice and Sagina procumbens from the Gough Island World Heritage Site. The economy of Tristan is based on its natural resources (fisheries) and also increasing efforts are being made to attract tourists due to the spectacular wildlife and landscape. While the eradication of mice and Sagina will not impact directly on livelihoods it will demonstrate Tristan's intent to protect its environment and subsequent publicity may increase interest and opportunities for Tristan. Funded by FCO/DFID Overseas Territories Environment Programme, 2009, project no TDC601 Multilateral Environmental Agreements World Heritage Convention Gough/Inaccessible Island is a natural World Heritage Site, one of two such in the UK OT's. The other, Henderson, also has as its major conservation issue the presence of introduced rodents, and RSPB, with OTEP funding is developing an eradication programme there. The OTEP funded feasibility study reports that: The Gough Island World Heritage Site is inscribed because it is one of the least-disrupted island and marine ecosystems in the cool temperate zone. The spectacular cliffs, towering above the ocean, are home to one of the world's largest colonies of sea birds. The island is also home to two endemic species of land birds, the gallinule [Gough moorhen] and the Gough rowettia [Gough bunting], as well as to 12 endemic species of plants. Article 5 of the Convention Concerning the Protection of the World Cultural and Natural Heritage notes that: To ensure that effective and active measures are taken for the protection, conservation and presentation of the cultural and natural heritage situated on its territory, each State Party to this Convention shall endeavor, in so far as possible, and as appropriate for each country: to take the appropriate legal, scientific, technical, administrative and financial measures necessary for the identification, protection, conservation, presentation and rehabilitation of this heritage; Convention on Biological Diversity Island biodiversity is one of seven 'thematic programmes'. A mouse eradication on Gough Island would reverse the loss of biodiversity at this site, and thus assist with meeting the 2010 biodiversity target. In particular, Article 8. In-situ Conservation. Each Contracting Party shall, as far as possible and as appropriate:& (f) Rehabilitate and restore degraded ecosystems and promote the recovery of threatened species, inter alia, through the development and implementation of plans or other management strategies;
(h) Prevent the introduction of, control or eradicate those alien species which threaten ecosystems, habitats or species; Convention on Migratory Species: Agreement on Conservation of Albatrosses and Petrels (ACAP) ACAP is highly relevant to Tristan, because the Territory holds significant populations of five longline-affected seabird species, of which three are endemic. Under Article III (general conservation measures) of ACAP, signatories are required to:
1. In furtherance of their obligation to take measures to achieve and maintain a favorable conservation status for albatrosses and petrels, the Parties, having regard to Article XIII, shall:
a) conserve and, where feasible and appropriate, restore those habitats which are of importance to albatrosses and petrels;
b) eliminate or control non-native species detrimental to albatrosses and petrels;
c) develop and implement measures to prevent, remove, minimize or mitigate the adverse effects of activities that may influence the conservation status of albatrosses and petrels; The Action Plan that forms Annex 2 of ACAP notes the following.
1.4 Non-native Taxa
1.4.2 The Parties shall take measures to the extent feasible to control and, where possible, eradicate non-native taxa of animals or plants, or hybrids there of, that are, or may be, detrimental to populations of albatrosses or petrels. Such measures should satisfy to the extent feasible, humane and environmental considerations.
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