Bell, E.; D. Boyle, K. Floyd, P. Garner-Richards, B. Swann, R. Luxmoore, A. Patterson, and R. Thomas. The ground-based eradication of Norway rats (Rattus norvegicus) from the Isle of Canna, Inner Hebrides, Scotland
The ground-based eradication of Norway rats (Rattus norvegicus) from the Isle of Canna, Inner Hebrides, Scotland
E. Bell1, D. Boyle1, K. Floyd1, P. Garner-Richards1, B. Swann2, R. Luxmoore3, A. Patterson4, and R. Thomas5 1Wildlife Management International Limited, 35 Selmes Road, Rapaura, RD3, Blenheim, 7273, New Zealand.
INTRODUCTION The Isle of Canna is located off the west coast of STUDY AREA AND METHODS Scotland in the Inner Hebrides (6o30’W, 57o03’N), and consists of two semi-connected main islands; Canna (1126 Canna and Sanday are naturally joined at low tide and ha) and Sanday (191 ha), and several small offshore stacks are now linked by a road bridge. Canna is approximately 8 and islets (Fig. 1). The Highland Ringing Group, which km long, east to west, and 2 km across at its widest point. has monitored the seabird colonies of the Isle of Canna for over 40 years had recorded that seabird populations (in particular razorbills (Alca torda), European shags (Phalacrocorax aristotelis) and Manx shearwater (Puffinus puffinus)) had been declining since the early 1990s (Swann 2002). Brown (Norway) rats (Rattus norvegicus) were identified as the most likely factor influencing this decline, from the observed increased predation on eggs and chicks (Swann 2002). Rats are known to have devastating effects on seabird populations, causing extinctions of birds on numerous islands throughout the world (Moors and Atkinson 1984; Atkinson 1985; Jones et al. 2008). Many islands have been successfully cleared of rats (Thomas and Taylor 2002; Howald et al. 2007) with a subsequent increase in bird populations (Towns and Broome 2003; Jones et al. 2008). The National Trust for Scotland (NTS) commissioned a feasibility study into the potential for the eradication of rats from Canna (Bell and Bell 2004), based on an earlier proposal (Patterson 2003). The Canna Steering Group, a partnership of NTS, Edinburgh Zoo, Scottish Natural Heritage (SNH), the Joint Nature Conservation Committee (JNCC) and Royal Society for the Protection of Birds (RSPB), decided that eradication of rats using a ground-based eradication technique was to proceed. Wildlife Management International Limited (WMIL) won the tender to direct the eradication with the assistance of NTS volunteers and staff. The three-phase Canna Seabird Recovery Project (Phase I eradication of Norway rats; Phase II monitoring for surviving rats and implementation of quarantine and contingency procedures; Phase III long- term monitoring of seabirds) began in August 2005 (Bell et al. 2006). Complete details of the project are available on Fig. 1 Location of Isle of Canna, Inner Hebrides, the project website (www.ntsseabirds.org.uk). Scotland.
Pages 269-274 In: Veitch, C. R.; Clout, M. N. and Towns, D. R. (eds.). 2011. Island invasives: eradication and management. IUCN, Gland, Switzerland. 269 Island invasives: eradication and management
With the exception of the in-bye land close to the farmhouse or from an early shipwreck. Only the Norway rat is known and buildings, Canna rises steeply from beach platforms on from the island and previous surveys recorded them in all all sides to a rolling plateau with the highest point at 210 m habitat types (Patterson and Brough 1999; Patterson and above sea level. Sanday is approximately 3 km long, east to Lloyd 2000; Patterson and Quinn 2001; Patterson 2003). west, and just over 1 km at its widest point. Sanday reaches Distribution, however, was not uniform with the highest 59 m a.s.l., but is similar to Canna with steep coastal cliffs, densities occurring around the in-bye land, the shoreline beach platforms and a low rolling plateau. and coastal slopes; a pattern common to most island Owned and managed by NTS, the Isle of Canna has situations where rats are dependent on foraging for food 15 permanent residents who maintain the farm and crofts, in inter-tidal zones and at seabird colonies. Other notable or manage the tourism ventures. The islands (i.e. both rat presence on the island was generally related to farming Canna and Sanday) are popular with visitors interested in activity, watercourses and rabbit habitat (Patterson 2003). the seabirds, raptors, flora and history. There are several The eradication option adopted for this project was a houses, crofts, farm buildings, churches, a lighthouse and ground-based poison programme using protective bait school. Canna has a jetty and is regularly serviced by the stations to reduce risk to non-target species, particularly Caledonian MacBrayne ferry from Mallaig. the white-tailed eagle and other raptor populations. The The islands are covered by maritime heath, coastal programme ran from 25 August 2005 to June 2008 and pasture and heather moorland, apart from Tarbert and in- included bait station establishment, capture of wood bye areas, which are improved pasture. There are also mice, poisoning, monitoring, quarantine and contingency, small areas of mixed woodland adjacent to the in-bye and a final check and rat-free declaration (Table 1). land. The island is grazed by domestic livestock including Each operational task was undertaken and completed as horses (Equus caballus), sheep (Ovis aries), and cattle follows: (Bos taurus); three feral goats (Capra hircus), and rabbits (Oryctolagus cuniculus). Canna also has three other small Bait station grid mammals; the pygmy shrew (Sorex minutus), house mouse The bait station grid was established between 3 (Mus musculus) and wood mouse (Apodemus sylvaticus). September and 27 October 2005. Bait stations were made Hedgehogs (Erinaceus europaeus) are also present. A from 750 mm lengths of 100 mm diameter corrugated small number of domestic cats and dogs are kept by the plastic drainage pipe, pegged to the ground with wire residents. “legs” to prevent movement by wind and/or stabilised with The Isle of Canna (excluding all the in-bye land) was rocks or other material to reduce interference by sheep, designated a Site of Special Scientific Interest (SSSI) in cattle, and ponies. Additional wires pushed through both 1987 for its biological and geological features. Following entrances reduced the entrance size to exclude smaller this, Canna was also designated in 1997 as a Special non-target species such as rabbits, hooded crows (Corvus Protected Area (as part of the European Union NATURA corone cornix) and gulls and to help secure the station to 2000 network of important bird sites) for its internationally the ground. Both entrances were raised slightly off the important concentrations of breeding seabird species. ground to deter entry by insects. Shags, razorbills, kittiwakes (Rissa tridactyla), puffins Bait was placed in the centre of the station through (Fratercula arctica), guillemots (Uria aalge), black a small access hole cut in the top which was covered by guillemots (Cepphus grylle) and fulmars (Fulmarus an additional short clip-on section of pipe as a lid. “Crow glacialis) all breed on the island. However, many of these clips” (a piece of wire across the station), as used during species are now in decline (Swann 2001, 2002). Historically, the Lundy Island rat eradication (Bell 2004), were also Manx shearwaters were also recorded to breed on the used to prevent crows from removing lids to access bait. island, but have declined to almost zero (Swann 2002). Bait stations were placed on a 50-metre grid on the Two pairs of white-tailed eagles (Haliaeetus albicilla) and coastal slopes and cliffs, the in-bye area and on Sanday a pair of golden eagle (Aquila chrysaetos) breed on the Isle (Fig. 2). On the higher plateau areas on Canna, stations of Canna, along with buzzards (Buteo buteo), peregrines were placed more widely at 100 m (Fig. 2). All areas, except (Falco peregrinus) and kestrels (Falco tinnunculus). steep or sheer cliffs with no vegetation had bait stations. All It is not known when rats became established on Canna; offshore rock stacks and islets had bait stations, as did areas but this is likely to have occurred more than two hundred with sizeable vegetation below steep cliffs with difficult years ago, either as an accidental introduction with supplies access. Ropes and a boat were used to access these areas.
Fig. 2 Bait station grid on Canna and Sanday (bait station positions are marked by a black dot).
270 Bell et al.: Eradication of rats, Canna, Scotland
In outdoor areas, each station was marked with a cane and minimised handling, and transferred without loss to flagging tape to ensure visibility in thicker vegetation or Edinburgh Zoo and the Highland Wildlife Park. during foggy conditions. Tube bait stations were also positioned along the Beach Poisoning Road and at the pier. Philproof and/or Protecta lockable First generation rodenticides were chosen for the stations were used inside all buildings. eradication campaign to minimise the risk of secondary Canna has numerous archaeological sites. WMIL, poisoning, particularly to birds. The main toxicant used NTS and Historic Scotland worked together to identify was a 28 g, cereal-based wax block bait with 0.005% important sites and,whenever possible, bait stations were active ingredient diphacinone (Ditrac, manufactured by placed outside recognisable structures (e.g., stone walls Bell Laboratories). The other rodenticide used was also a and remnant houses). If this was not possible, one or 28 g cereal-based wax block bait but with 0.005% active two stations were positioned in the best possible way to ingredient bromadiolone (Contrac, also manufactured by minimise disturbance or damage to the site. These sites Bell Laboratories). However, only three blocks of Contrac were identified on maps for the field team and access to all bait were deployed at one location. Both types of bait were archaeological sites was limited to work purposes only. dyed blue (or green/blue), which makes them less attractive to birds. The entire grid of 4388 stations was positioned before being individually numbered and mapped using GIS The bait was delivered to Canna on 28 October 2005 (Manifold). Since Norway rats are reputedly neophobic and was transported to depots around the island by tractor and can be wary of new items placed in their environment, and trailer and/or all terrain vehicle (ATV) and trailer. the grid was left for a period of two to six weeks to allow The poisoning programme (Phase I) commenced on 1 the rat population time to become familiar with it. November 2005 and continued through to 6 March 2006. Baits were present in each station throughout the Capture of wood mice poisoning programme and replaced as required, when eaten It is thought that the race of wood mouse found on by rats or non-target species and/or damaged by weather. Canna is distinct, possibly a sub-species of the wood Ten bait blocks were available in each bait station for most mouse found on the Scottish mainland (Berry et al 1967; of the programme but this was reduced to three blocks Lloyd 2000; Patterson 2003) as it is larger and more golden when rat activity waned towards the end of the poisoning than the mainland population (Patterson 2003). Eradication phase (6 January 2006). By mid February these bait blocks programmes can have an associated risk that non-target were wired into the stations to ensure missing baits were species will be poisoned either by direct consumption being taken by surviving rats rather than non-targets as or through secondary poisoning. Principle preventative crows and cattle sometimes shook the stations to displace methods can include the design of the bait station, but the and consume the bait. Canna wood mouse was small enough to gain direct access The majority of stations (n = 4229) were checked and to the bait as well as being at risk from secondary poisoning serviced every three to six days (November and December by eating invertebrates that have eaten the bait. The spacing 2005) or every 15 to 20 days (January to March 2006). of the bait station grid meant the chance of accidentally However, difficult to access bait stations (n = 66) in tide, eradicating the Canna wood mouse was unlikely (due to weather, rope or boat dependent areas) were loaded with their small home range), but it was decided that a small, but thirty blocks per station and checked whenever possible. viable ‘assurance’ population would be live-captured and Permanent bait stations (n = 93) established in the held as two captive sub-populations at Edinburgh Zoo and farmyard and buildings around the island were regularly the Highland Wildlife Park for the duration of the baiting inspected and maintained as required with ten blocks into period. each station. The translocation of wood mice was undertaken by staff To present the data on bait take gained from these from The Royal Zoological Society of Scotland during the varied bait station checks we grouped the data into 12 bait station establishment period from 8 September to 3 periods or checks (mean (±SEM) = 9.6 ± 1.8 days between November 2005. Longworth live traps were deployed checks, range 3-22 days) shown as days from baiting (Figs. in a range of habitat types and locations over Canna and 3 and 4). Sanday. Traps were run for three nights at each site before being moved to alternative sites. Traps containing bedding Towards the end of the poisoning phase (15 February - materials were baited with grain and invertebrates and 6 March 2006), when isolated incidents of rat activity, such checked every four hours. A total of 158 wood mice were as teeth marks or droppings, were detected in a monitoring captured. All individuals were maintained and transported or bait station, an additional bait block was staked inside in North Kent Plastic MB1 laboratory rat cages which the entrance of an identified rat hole in the vicinity and/
Table 1 Timetable of activity on the Canna Seabird Recovery Project Dates Phase Activity 27 August 2005 Team arrive on Canna 3 September to 27 October 2005 Bait station grid established 8 September to 3 November 2005 PHASE I Capture of wood mice 28 October 2005 Poison arrives 1 November 2005 to 6 March 2006 Poisoning operation 13 December 2005 to 27 March 2006 Intensive monitoring (M1) 28 March to 23 September 2006 Long-term monitoring (M2) 24 September to 19 December 2006 Intensive monitoring (M3) 20 December 2006 to 10 March 2008 PHASE II Long-term monitoring (M4) 11 to 28 March 2008 Final check and quarantine and contingency audit (M5) 2 to 9 May 2008 7 June 2008 Declaration of rat-free status
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Fig. 3 Amount (kg) of bait consumed by rats at each bait check (marked by black dot) during the Norway rat eradication on the Isle of Canna, Inner Hebrides, Scotland. Fig. 4 Amount (kg) of bait consumed by non-target species at each bait check (marked by black dot) during the Norway rat eradication on the Isle of Canna, Inner or inside a purpose made ‘natural’ bait station such as a Hebrides, Scotland. tunnel made from rocks. Both types of bait were used on these occasions, placed out of sight and reach of non-target species by covering entrances with rocks, vegetation or Each monitoring site was checked regularly, either wire netting. These natural sites were marked with flagging separately or together with the poisoning bait station grid. tape, numbered and added to the bait station grid. Both rat and non-target species sign found on detection Bait take was recorded in field notebooks by bait devices was recorded and added to the database. If rat sign station number and the species believed to have consumed (usually tooth marks) was detected, an intensive poisoning or removed the bait. These data were entered into a data (bait stations at 25-m) and trapping (snap traps) programme base and large-scale maps showing active stations were was established around the site. produced in real-time to enable the team to effectively monitor bait take activity and target any “hot spots”. All rat RESULTS corpses found were collected and returned to base for safe disposal to reduce risk for non-target scavengers. Bait acceptance and take Green/blue rat droppings appeared within five days Monitoring of baiting and rats accounted for 540 kg of bait taken Five distinct periods of monitoring were undertaken (estimated 3000-5000 rats). The bait take pattern was as the project progressed (Table 1). Intensive monitoring typical of other Norway rat eradication campaigns (Thomas (M1) using 5296 stations at 50 m spacing was carried and Taylor 2002). It was very high six days after original out from 13 December to 27 March 2006 to detect rats baiting (1st check) and dropped to a relatively low level 28 surviving through the poisoning phase. This was followed days after original baiting (5th check). A small increase was by a six-month period of long-term monitoring (M2), recorded at day 32 after the original baiting (6th check), from 28 March to 23 September 2006. A second intensive but dropped away to a low level throughout the rest of the monitoring period (M3), utilising 7608 stations, was poison programme, reaching zero bait take on day 64 after completed from 24 September to 18 December 2006 the original baiting (9th check) (Fig. 3). followed by a period of long-term monitoring (M4) using Throughout the poisoning phase, 62% of bait stations 801 stations from 20 December 2006 to 10 March 2008. were visited by rats, with 50% active within the nine days These were established at high risk areas on the island; of the original baiting. The low percentage of active stations around the coastal seabird breeding sites, Beach Road, shows that rats were not distributed evenly across the island at the pier, around the farmyard, in out-buildings, in all nor were they in high numbers. This was reflected in bait properties and around the coast of Sanday (Bell et al take levels on the slopes. Ten percent of the bait stations 2006, 2007, Table 1). The final check (M5), using 1610 had more than 12 blocks taken, and 3% had more than 21 stations, was carried out between 11 and 28 March 2008. baits taken by rats. On the plateau, 12 blocks were taken WMIL staff and NTS volunteers carried out the intensive from 4% of the stations and 21 blocks from 1% of stations and final checks and NTS staff maintained the long-term (Fig.5). monthly monitoring over summer. There were two types of monitoring stations using rat attractive food items; one was The coastal cliff areas, where breeding seabird colonies secured to the ground by a wire and the other was secured are established during summer, also had high bait take by inside a tube station. Both were individually numbered and rats, as did sites at Geugasgor, Lamasgor, Iolasgor, and the any evidence of activity (i.e. teeth marks) was recorded in Nunnery where shag colonies are present during summer. field notebooks by station number and the species believed There were few stations on the cliffs or slopes that had no to have consumed or marked the monitoring item. bait take by rats (Fig. 5). Monitoring items such as soap, chocolate, chocolate Bait take was also high on the offshore stacks and littoral wax, and candles (but most frequently chocolate wax) areas of the main island accessed by boat (Fig. 5). Every were placed inside and outside each station. Mud traps of bait station on the rock stacks had at least ten bait blocks mud smoothed out to detect rat foot prints were established taken, as did many of the shoreline stations on Canna. on stock feeding sites, Tarbert Barn, Beach Road and at the The average number of blocks taken by rats was 8.06 pier. Checking for active rat burrows and rat runs, along (± 1.01) blocks per active station (n = 2732). The average with trapping at Tarbet Barn, was also undertaken. number of blocks taken per station (n = 4388) was 4.4
272 Bell et al.: Eradication of rats, Canna, Scotland
Fig. 5 Distribution of total bait take by rats (as bait blocks consumed per station) during the entire Norway rat eradication on the Isle of Canna, Inner Hebrides, Scotland.
(± 0.1). However, 38% of stations had no bait taken by rats (and these mainly restricted to wood mice and pygmy and 54% had six or fewer blocks taken by rats. shrews). Bait-take showed that the rat population was low There were low to moderate levels of interference by to moderate and not evenly distributed across the island. non-target species (Fig. 4). Cattle trampled bait stations, High concentrations on the coastal slopes meant rats would ate bait (<200 kg) and removed numbered tags. Ponies, have had an effect on nesting seabirds. sheep and goats had minor impact that was generally Problems encountered were few and mainly limited to related to removing numbered tags or knocking over weather and interference with bait and monitoring stations poles. Stock were not affected by the poison during the by non-target species. Although wood mice were recorded eradication. Crows (and other birds) ate moderate amounts taking bait and a small number of losses did occur, the of bait (<120 kg) and green regurgitation pellets were seen population quickly recovered in numbers and range after at known crow roost sites. No birds were found killed by the removal of rats. Since the wood mouse population was poison during the eradication operation. Wood mice (< 15 recovering naturally there was no requirement to reintroduce kg), pygmy shrews (<2 kg) and insects and slugs (<25 kg) individuals taken into captivity. Ten of the captive Canna consumed small amounts of bait. Five wood mice and two wood mice have been used in an unrelated mark-recapture pygmy shrew carcasses were found during the eradication study and the remainder held at the Highland Wildlife Park operation. More than three tonnes of bait was lost to weather as a permanent display. events, particularly on the coastal cliffs during storms. There is no doubt that the eradication of Norway rats from Canna will benefit the recovery of breeding seabirds. Monitoring Manx shearwaters were presumed to be extinct on the Monitoring for rat presence continued island wide island, but a few individuals were still present (Swann (Canna and Sanday) for two years after the end of the 2008) and the first chick to be recorded on the island in poisoning operation. ten years was found and banded in September 2006 (A. Three rats were detected on Canna during the four- Ramsay, Caledonian Ornithological Services pers. comm.). month period when monitoring overlapped the end of the This increases the possibility for successful recovery of poison operation (last rat detected on 20/2/06). These were the Manx shearwater population. There are also increases caught using traps and the alternative Contrac bait. No rats in productivity and/or numbers of puffins, razorbills and or sign were detected during monitoring after the end of the European shags (Swann 2008; Bob Swann pers. obs.). The poisoning operation. Rat-free status for the Isle of Canna seabird populations will continue to be monitored by the was declared in June 2008. Highland Ringing Group. The wood mouse population on both Canna and Sanday With rats gone from Canna, it is important that they recovered quickly after the eradication. Wood mice tooth are never provided with an opportunity to re-establish on marks were recorded at more than 75% of the monitoring the island. As a permanently inhabited island, the greatest points during sessions M1 to M5. Rabbits left tooth marks risks of rats reaching Canna comes from infested fishing on devices at 23% of the monitoring points and pygmy boats mooring overnight, from equipment and food being shrew tooth marks were recorded at 17% of monitoring brought to the island (via the Caledonian MacBrayne ferry sites. or other vessels); and with visitors to the island. A rodent quarantine and contingency plan was developed which DISCUSSION minimises the risk of rats being re-introduced, without being too onerous for island residents, ongoing projects, The success of the Isle of Canna rat eradication and visitor programmes (Bell et al. 2007, 2008; Bell and campaign shows that a well-planned, adequately resourced, Garner-Richards 2006). well-executed programme, supported by the landowner Bait stations have been established on the mainland and residents and directed by experienced operators can (on Mallaig pier) and on the neighbouring islands of Rum, eradicate brown (Norway) rats from a large inhabited Eigg, and Muck which are not rat-free, but have some island using a ground-based poisoning technique. level of rodent control. Bait stations are maintained on the Once set up, the island was cleared of rats within six Caledonian MacBrayne ferry and landing-craft that service weeks (42 days from original baiting; 9th check) with very the island. Bait stations and trapping points have been few secondary and primary non-target species affected established on Canna pier, Beach Road, farm buildings,
273 Island invasives: eradication and management tearooms, food storage areas, residents’ homes, and guest Bell, E.A. and Bell, B. 2004. An assessment of the proposal to eradicate accommodation. Rodent ‘motels’ (i.e. large wooden boxes brown rats from the Isle of Canna, Scottish Hebrides. Unpublished that act as an attractive shelter and nesting area for rodents report to the National Trust for Scotland, Edinburgh, Scotland. into which traps and monitoring items can be placed) have Bell, E.A.; Boyle, D.; Garner-Richards, P.E. and Floyd, K. 2006. Canna Seabird Recovery Project: Phase 1: eradication of brown rats 2005- been placed in all high risk areas. All staff and residents 06. Unpublished report to the National Trust for Scotland, Edinburgh, on the island have been trained in quarantine methods, Scotland. rodent sign and detection. One resident NTS staff member Bell, E.A.; Boyle, D.; Garner-Richards, P.E. and Floyd, K. 2007. Canna has been made responsible for enforcement of quarantine Seabird Recovery Project: Phase 2: intensive monitoring 2006. and implementation of any contingency action. Rodent- Unpublished report to the National Trust for Scotland, Edinburgh, proof areas have been identified for unpacking suspicious Scotland. or high-risk containers. All visitors to the island and boat Bell, E.A.; Garner-Richards, P.E. 2006. Isle of Canna: Quarantine and owners mooring offshore are informed of the rat-free status Contingency Procedures. Unpublished report to the National Trust for of the island and are asked to be vigilant for rats and rat Scotland, Edinburgh, Scotland. sign. Bell, E.A.; Tayton, J.; Garner-Richards, P.E.; Floyd, K. and Boyle, D. A contingency protocol was developed for Canna that 2008. Eradication of brown rats from Isle of Canna: final monitoring check and quarantine and contingency audit; March to May 2008. details procedures for interviewing persons who report Unpublished report to the National Trust for Scotland, Edinburgh, a rat sighting, inspecting the location of the sighting, Scotland. determining if this is a likely rat event, establishing and Bell, M.D.; Bullock, I. and Humpridge, R. 2000. The eradication of rats maintaining monitoring, trapping and/or baiting grids, from Ramsey Island. Wales. Unpublished report prepared for Royal identifying tooth marks (or other sign) and reporting and Society for the Protection of Birds, UK, by Wildlife Management recording all incidents (Bell and Garner-Richards 2006). International Limited. New Zealand. Rodents have now been successfully eradicated from Berry, R.J.; Evans, I.M. and Sennitt, B.F.C. 1967. The relationship and islands ranging in size from 1 to 11,200 ha throughout the ecology of Apodemus sylvaticus from the small isles of the Inner world. The successful eradication of rats from Ailsa Craig Hebrides, Scotland. Journal of Zoology (London) 152: 333-346. (100 ha; Zonfrillo 2001, 2002), Handa Island (Stoneman Howald, G.; Donlan, C.J.; Galvan, J.P.; Russell, J.C.; Parkes, J.; Samaniego, and Zonfrillo 2005), Ramsey Island (256 ha; Bell et al. A.; Wang, Y.; Veitch, D.; Genovesi, P.; Pascal, M.; Saunders, A. and 2000), Lundy Island (500 ha; Bell 2004) and now the Tershey, B. 2007. Invasive rodent eradication on islands. Conservation Isle of Canna (1300 ha), demonstrates how ground-based Biology 21: 1258-1268. poisoning operations can be effectively applied on islands Jones, H. P.; Tershy, B. R.; Zavaleta, E. S.; Croll, D. A.; Keitt, B. S.; Finkelstein, M. E. and Howald, G. R. 2008. Severity of the effects of around the UK and Europe. The success on Canna builds invasive rats on seabirds: A global review. Conservation Biology. 22: on the efforts of many projects that have gone before and 16-26. lessons learnt will be invaluable for future eradication Lloyd, L. 2000. Small mammal populations on the Inner Hebridean programmes, particularly those with important non-target Island of Canna, Scotland: implications for rat control. Unpublished species. It also shows that ground-based eradication Master of Science thesis. University of Edinburgh, Scotland. techniques can be adapted for, and undertaken on, Moors, P.J. and Atkinson, I.A.E. 1984. Predation on seabirds by introduced permanently inhabited islands of various sizes, and serves animals and factors affecting its severity. In: Croxall, J.P, Evans, P.G.H. as a good example of the significant long-term benefits that and Schreiber, R.W. (eds.). Status and conservation of the world’s can be achieved through short-term investment. seabirds, pp. 667-690. ICBP Technical Publication 2. Patterson, A. 2003. Seabird conservation on the islands of Canna and ACKNOWLEDGEMENTS Sanday. Unpublished report to The National Trust for Scotland, 15 pp. This project was funded by the European Union (EU) Patterson, A. and Brough, C. 1999. Small mammal survey on the island of LIFE Programme, The National Trust for Scotland (NTS), Sanday. Unpublished report to The National Trust for Scotland. the Royal Zoological Society for Scotland (RZSS) and Patterson, A. and Lloyd, L. 2000. Small mammal survey on the island Scottish Nature Heritage (SNH). We would like to thank of Canna. Unpublished report to The National Trust for Scotland, all the WMIL staff and NTS volunteers who worked on Edinburgh, UK. Canna; all the Islanders (in particular Patrick and Wendy Patterson, A. and Quinn, S. 2001. Rat survey on the island of Canna Mackinnon, Kathryn Mackinnon, Gerry Mackinnon and and Sanday. Unpublished report to The National Trust for Scotland, Murdo Jack); Canna Seabird Recovery Project Steering Edinburgh, UK. Group; NTS staff (in particular John Hollingsworth, Les Stoneman, J. and Zonfrillo, B. 2005. The eradication of brown rats from Smith and Euan Turner); Graham Tucker (EU); RZSS Handa Island, Sutherland, Scotland. Scottish Birds 25: 17-23. staff (in particular Gareth Bennett, Edwin Blake, Fraser Swann, R.L. 2001. Canna Seabird Studies 2000. JNCC Report 314. Dodds and Gavin Harrison); Martin Carty; RJ McLeod’s; Swann, R.L. 2002. Canna Seabird Studies 2001. JNCC Report 327. Don Merton; Bill Simmons; Bill Cash; Steve Ebbert, Peter Dunlevy and Lisa Sharf (Alaska Maritime National Swann, R.L. 2008. Canna Seabird Studies 2007. JNCC Report 376. Wildlife Refuge); Will Golland and May-Ellen Spoerke Thomas, B.W. and Taylor, R.H. 2002. A history of ground-based rodent (Bell Laboratories Ltd); Mark Lambert (Central Science eradication techniques developed in New Zealand, 1959-1993. In: Laboratories); Sanitarium (NZ) Ltd; Hubbards (NZ) Ltd; Veitch, C.R. and Clout, M.N. (eds.). Turning the Tide: the eradication of invasive species, pp. 301-310. IUCN, Gland, Switzerland and Tunnocks Ltd; Shipton Mill; Caledonian MacBrayne Cambridge, UK. Ltd; Fisher Scientific Supplies; Carberry Candles; Prices Patented Candles Limited; and Rentokil (UK) Ltd. Towns, D. R. and Broome, K. G. 2003. From small Maria to massive Campbell: Forty years of rat eradications from New Zealand islands. New Zealand Journal of Zoology, 30: 377-398. REFERENCES Zonfrillo, B. 2001. Wildlife Conservation on Ailsa Craig. The Thomas Atkinson, I.A.E. 1985. The spread of commensal species of Rattus to Duncan Memorial Lectures. Friends of the McKechnie Institute, 22 pp. oceanic islands and their effects on island avifaunas. In: Moors, P.J. (ed.). Conservation of island birds, pp. 35-81. ICBP Technical Publication 3. Zonfrillo, B. 2002. Puffins return to Ailsa Craig. Scottish Bird News 66: 1-2. Bell, E.A. 2004. Seabird Recovery Project, Lundy Island, Bristol Channel, UK: 2002-2004: Final Report. Unpublished report to Lundy Seabird Recovery Project Partnership co-ordinated by Royal Society for the Protection of Birds. South-west Regional Office, Devon, UK.
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