Rattus Norvegicus) from the Inhabited Islands of St Agnes and Gugh, Isles of Scilly
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E. Bell, K. Floyd, D. Boyle, J. Pearson, P. St Pierre, L. Lock, P. Buckley, S. Mason, R. McCarthy, W. Garratt, K. Sugar and J. Pearce Bell, E.; K. Floyd, D. Boyle, J. Pearson, P. St Pierre, L. Lock, P. Buckley, S. Mason, R. McCarthy, W. Garratt, K. Sugar and J. Pearce. The Isles of Scilly seabird restoration project: the eradication of brown rats (Rattus norvegicus) from the inhabited islands of St Agnes and Gugh, Isles of Scilly The Isles of Scilly seabird restoration project: the eradication of brown rats (Rattus norvegicus) from the inhabited islands of St Agnes and Gugh, Isles of Scilly E. Bell1, K. Floyd1, D. Boyle1, J. Pearson2, P. St Pierre2, L. Lock2, P. Buckley2, S. Mason3, R. McCarthy4, W. Garratt5, K. Sugar6 and J. Pearce7 1Wildlife Management International Limited, PO Box 607, Blenheim 7240, New Zealand. <[email protected]>. 2Royal Society for the Protection of Birds, UK Headquarters, The Lodge, Sandy, Bedfordshire SG19 2DL, United Kingdom. 3Isles of Scilly Wildlife Trust, Trenoweth, St. Mary’s, Isles of Scilly TR21 0NS, UK. 4Lowertown Cottage, St Agnes, Isles of Scilly, TR22 0PL, United Kingdom. 5Duchy of Cornwall, Hugh House, St Mary’s, Isles of Scilly. TR21 0HU, UK. 6Natural England, Polwhele, Truro, Cornwall. TR4 9AD, UK. 7Isles of Scilly Area of Outstanding Natural Beauty, Council of the Isles of Scilly, Town Hall, St Mary’s, Isles of Scilly. TR21 0LW, UK. Abstract As part of the Isles of Scilly Seabird Recovery Project, and directed by Wildlife Management International Ltd, the eradication of brown rats (Rattus norvegicus) from the inhabited islands of St Agnes & Gugh, Isles of Scilly was completed between October 2013 and April 2014 with the assistance of volunteers, and staff from the Royal Society for the Protection of Birds, Isles of Scilly Wildlife Trust and Natural England. Bait stations with cereal-based wax blocks containing bromadiolone at 0.005% w/w were established on a 40–50 metre grid over the island. With the presence of 85 residents on the 142 ha islands, this is the largest community-based brown rat eradication globally to date. Given the fact that a community is based on these islands, community engagement and advocacy was a vital and fundamental part of the eradication. Consultation for eradication began three years prior to the operation to explain the requirements for the proposed project and to assess support, but this built on many years of wider community engagement with seabird conservation. All of the residents supported the eradication of rats and vision of the project. The consultation and inclusion of the community in decision-making and management of the Isles of Scilly Seabird Recovery Project was a critical part of the operation and key to the success of the eradication. The community took ownership of the project and has committed to the on-going biosecurity requirements following the eradication of rats. The removal of brown rats from St Agnes and Gugh was a major achievement and provided the opportunity to restore the islands’ communities of seabirds and other native species. This project provided an example of the eff ectiveness of ground-based rodent eradication techniques on an inhabited island and the lessons learnt during this operation can be used to help proposed eradications on other islands with communities and with terrain suitable for ground-based techniques. Keywords: brown rat, community, eradication, Isles of Scilly, Rattus norvegicus, St Agnes and Gugh INTRODUCTION The eradication of invasive species from islands has The Isles of Scilly are a nationally and internationally become one of the most important tools in conservation important location for seabirds, particularly Manx shearwater in recent times. It off ers the opportunity that, following (Puffi nus puffi nus), European storm petrel (Hydrobates an initial investment, signifi cant long-term benefi ts pelagicus) and black-backed gull (Larus fuscus) (Lock, can be achieved. The eradication of rats is a recognised et al., 2006). Both Manx shearwaters and European storm prerequisite for the restoration of many seabird colonies on petrels are amber listed under the United Kingdom Birds islands. Rodents have been successfully eradicated from of Conservation Concern threat categorisation (Eaton, et over 700 islands around the world, including at least 10 al., 2015). A partnership of organisations (Royal Society UK islands (Moors & Atkinson, 1984; Atkinson, 1985; for the Protection of Birds (RSPB), Natural England (NE), Taylor, et al., 2000; Zonfrillo, 2001; Towns & Broome, Isles of Scilly Wildlife Trust (IOSWT) and Isles of Scilly 2003; Appleton, et al., 2006; Howald, et al., 2007; Jones, Bird Group (IOSBG)) produced the Isles of Scilly Seabird et al., 2008; Bell, et al., 2011; Parks & Wildlife Service, Conservation Strategies 2005–2008 and 2009–2013 2014; DIISE, 2015; Thomas, et al., 2017; Bell, 2019; Bell, which described the national and international status and et al., 2019; Pearson, et al., 2019), However, most of context of the seabird populations on the Isles of Scilly these islands have been uninhabited. Many consider that and identifi ed priority actions and strategic goals for islands with signifi cant human populations, unreceptive management. These included current and future measures communities or occurrence of livestock and domestic to improve the available habitat for seabirds through rat animals are unlikely to be feasible for eradication (Oppel, et control and eradication (Lock, et al., 2006; Lock, et al., al., 2011; Campbell, et al., 2015; Russell & Broome, 2016; 2009). St Agnes and Gugh have a number of important Stanbury, et al., 2017). However, an increasing number of land areas designated for seabirds as Special Protected eradications are being considered on inhabited islands and Areas (SPA), Sites of Special Scientifi c Interest (SSSI) the importance of the engagement and inclusion of local and Ramsar (Lock, et al., 2009). The eradication of communities has been highlighted in a number of recent brown rats (Rattus norvegicus) from St Agnes and Gugh eradication and research projects, especially in regard was identifi ed as a priority in these strategies as it would to risk and benefi t analysis (Eason, et al., 2008; Bryce, remove predation pressure on Manx shearwaters and storm et al., 2011; Oppel, et al., 2011). It should be noted that petrels and provide the opportunity for other seabirds to the greatest conservation benefi t to be gained from future colonise the islands (Lock, et al., 2006; Lock, et al., 2009). eradications in the UK, and in other parts of the world, These strategies also recognised the social, economic and is predominantly from inhabited islands (Stanbury, et al., health benefi ts for the local community (Lock, et al., 2006; 2017). As such, it is vital that techniques and protocols Lock, et al., 2009). developed during eradications on islands with even small communities should be assessed, utilised or adapted for The Isles of Scilly Seabird Recovery Project (IOSSRP) these islands with larger communities. was established in 2010 and was managed by a coalition of In:88 C.R. Veitch, M.N. Clout, A.R. Martin, J.C. Russell and C.J. West (eds.) (2019). Island invasives: scaling up to meet the challenge, pp. 88–94. Occasional Paper SSC no. 62. Gland, Switzerland: IUCN. Bell, et al.: Rats off inhabited St Agnes and Gugh, UK groups including RSPB, IOSWT, NE, Duchy of Cornwall are landed, and a smaller slipway used mainly by residents. (DC), the Isles of Scilly Area of Outstanding Natural Beauty These factors increased the number of challenges such as (AONB) partnership and a representative from St Agnes providing alternative food and shelter for rats, risk to non- and Gugh, with support from the IOSBG. The IOSSRP target species and biosecurity. partnership identifi ed the need to assess the possibility of eradicating brown rats from St Agnes and Gugh to protect The main habitats on St Agnes are farmland, mainly and enhance the islands’ seabirds and protect Annet from fl ower farms and low intensity cattle grazing, characterised re-invasion. Annet is the most important uninhabited island by small fi elds with extensive hedges and stone walls, for seabirds in the Isles of Scilly as it has always been ponds, maritime grassland, invasive Pittosporum, rocky rat-free (excluding an incursion in 2004, probably from shores and sandy beaches (Parslow, 2007). St Agnes and neighbouring St Agnes) and holds the main populations Gugh are home to the only known populations in the British of Manx shearwaters and European storm petrels (Lock, Isles of a number of rare plants, including least adder’s- et al., 2006). The partnership commissioned a feasibility tongue fern (Ophioglossum lusitanicum) (Parslow, 2007). assessment in 2010 (Bell, 2011). A formal IOSSRP Rabbits (Oryctolagus cuniculus), Scilly shrews Steering Group made up of representatives from all Project (Crocidura suaveolens cassiteridum) and pipistrelle bats Partners was established in 2012. Wildlife Management (Pipistrellus spp.) are the only other known species of International Ltd. (WMIL) directed the eradication with mammal found on St Agnes and Gugh, apart from livestock the assistance of volunteers and RSPB, IOSWT and NE and pets. House mice (Mus musculus domesticus) were staff . The eradication was completed between October present on St Agnes and Gugh, but have not been seen in 2013 and April 2014 (Bell, et al., 2014). This paper covers at least 15 years, though mice are still present on most of the technical aspects of the St Agnes and Gugh brown the other main islands in the Scillies (Howie, et al., 2007). rat eradication and complements the Pearson, et al., (this issue) paper on the community aspect of the eradication. Eradication operation The eradication programme ran from 11 October 2013 STUDY AREA AND METHODS to 11 April 2014 and included establishing the bait station St Agnes and Gugh grid, poisoning, monitoring and biosecurity establishment.