233

INTRODUCTION

Advances worldwide in rodent control or eradication on islands during the past three decades have centred on the use of rodenticides (Howald et al. 2007). However, the propensity for rodents to develop a tolerance for toxicants (Bailey and Eason 2000) and increasing public opposition to use of poisons may limit their continued use, particularly in mainland situations (Williams 1994; Towns and Broome 2003; Mason and Littin 2003; Towns et al. 2006). Traps have similarly evolved in design and strategic use but they also attract a public opposition, ostensibly over animal welfare issues.

The New Zealand Department of Conservation (DOC) requires a better performing snap trap that gives more consistent catch/kill rates; improved animal welfare outcomes; less non-target catch and environmental interference; enable higher quality trapping data; have greater durability; less maintenance; quicker servicing during routine checks; and are easier for operators to use than current preferred rodent traps. In short, better returns from traps in relation to money expended (Keith Broome pers. comm., April 2004).

In this paper, we describe the development and field trials of Ka Mate (KMT) reverse-bait snap traps, which have been designed to meet modern efficacy and animal welfare requirements.

Traditional, wooden based “break-back” traps (snap traps), have been used in New Zealand since at least 1920, particularly for bio-security at ports, rodent control around factories, and as a health measure in urban environments (Wodzicki 1950). They have also been used internationally for scientific data collection and in conservation management programmes (Bull 1946; Watson 1956; Wodzicki 1969; Daniel 1973; Innes et al. 1995; Dunlevy et al. 2000; Efford et. al. 2006; Malcolm et al. 2008; Theuerkauf et al. 2010). More recently, snap traps have been employed in many large-scale New Zealand mainland island rodent control programmes (Saunders 2000, 2003; Speedy et al. 2007; Ogden and Gilbert 2008) and as adjuncts to toxicants in island eradication campaigns (Morrell et al. 1991; Taylor et al. 2000; Merton et al. 2002; Thomas and Taylor 2002; MacKay and Russell 2005; Nugent et al. 2007; Witmer and Burke 2007; Varnham 2010).

Rats have been eradicated from at least two islands of up to 21 ha with snap traps (Moors 1985; MacKay and Russell 2005; Howald et al. 2007), but trapping is usually considered to be too labour intensive and expensive as a sole eradication technique for rats (Keith Broome pers.

comm.). Poor trap performance has exacerbated negative public attitudes, resulting in stricter rules for trapping and animal welfare now embedded in policy and law (Mason and Litten 2003; Powell and Proulx 2003; Litten et al. 2004).

Traps have traditionally varied from toggle trigger traps with a small (baited) trigger to large treadle plate designs that use a lure to entice target species to step onto a plate to spring the device. Treadle snap traps are generally easier to use than trigger traps. Many trap designs are operationally unstable and not robust enough to withstand the rigours of long term field use. Baseboards on wooden models warp or split, staples pull and weak points on plastic variations soon break. The larger trigger area of treadle traps makes them more prone to misfire due to environmental events and the presence of non target species.

THE KA MATE REVERSE-BAITING SNAP TRAP

Trap developmentDuring the mid-1980s, two of us (RT and BT)

experimented with ways to improve snap trap efficiency. Modifications were made to wooden based trigger “Ezeset” traps being used to catch Norway rats (Rattus norvegicus) which led to “reverse-baiting” snap traps with dense, supportive bait beneath rather than on top of the trap trigger. This utilised the bait as a removable structural component of the trap, introducing significantly more stability into the trigger function.

Six steel reverse-bait snap traps were then engineered in 2003 and of the five ship rats (Rattus rattus) these first killed, three were cranial and two were humane neck strikes. Fifty of these traps were subsequently incorporated into a 6 month paired trial with “Victor Professional” traps at Weka Bush, Nelson Lakes National Park. In 2005, 100 handmade aluminium prototypes (Fig. 1), which we called Ka Mate (KMT) traps, were integrated with the steel traps into an alternating trap trial with “Victor Professional” rat traps and tested over 13 months in Nelson Lakes Big Bush rodent control area. Another 100 KMT prototypes were included in an alternating trap trial with Victor Professional rat traps in DOC’s 2005 trap research programme in Te Urewera National Park.

The KMT traps caught and killed mice (Mus musculus), rats (Rattus rattus), weasels (Mustela nivalis), stoats (M. erminea) and hedgehogs (Erinaceus europaeus). In the Te Urewera trial, the KMT traps also had far fewer

The Ka Mate reverse-bait snap trap – a promising new development

B. Thomas¹, R. Taylor², P. Dunlevy³, K. Mouritsen4, and J. Kemp5 ¹Ka Mate Traps Ltd, 190 Collingwood St., Nelson 7010, New Zealand. <bruce@kamatetraps.com>. ²13 Templemore Drive, Richmond 7020, New Zealand. ³USDA-APHIS Wildlife Services, 3375 Koapaka Street, Honolulu, HI 96819, USA. 4 Waiaro Sanctuary, P.O. Box 6, Colville 3584, New Zealand. 5 Department of Conservation, Private Bag 5,

Nelson 7042, New Zealand.

Abstract Development, field trials and potential of Ka Mate reverse-bait snap trap are described. Prototypes were tested on five species of rodents in a range of environments in New Zealand, Alaska, Hawaii, Wake Atoll, Wallis & Futuna Islands, New Caledonia and Seychelles. Paired testing of reverse-bait traps in close proximity to treadle traps was found to be inappropriate because trap function combined with animal behaviour skewed results. The first factory product, the Ka Mate medium “safeTcatch” trap, the corflute “flatpack” trap station and various wax baits are now under evaluation by professional conservation and science practitioners worldwide. One example is Waiaro Sanctuary (Coromandel, New Zealand) where in one year, using only Ka Mate rat traps, 75 ha of forest yielded 656 rats, reducing population indices from 100% tracking tunnel rates to 10%. Data indicates that over 95% of rats were trapped with head/neck strikes, and only one bird was caught in Waiaro in circa 90,000 trap nights using Ka Mate traps set unprotected on the forest floor.

Keywords: Ka Mate traps, reverse-bait snap trap, treadle trap, Victor, Catchmaster, Ezeset, Mus, Rattus, Wake Atoll, Wallis and Futuna Island, Waiaro Sanctuary, New Zealand.

Pages 233-238 In: Veitch, C. R.; Clout, M. N. and Towns, D. R. (eds.). 2011. Island invasives: eradication and management. IUCN, Gland, Switzerland.

Thomas, B.; R. Taylor, P. Dunlevy, K. Mouritsen, and J. Kemp. The Ka Mate reverse-bait snap trap – a promising new development

Island invasives: eradication and management

234

unsprung/bait missing events than Victor traps (2 versus 71, respectively), indicating that the reverse-bait trigger reduced problems with non-target and environmental triggering. When compared with wooden-based wire striker traps, operators also found the aluminium KMT to be the safest to set and handle, easiest to clean and maintain (Fig. 1), required the least service time during routine checks, and had the greatest durability in the field (Paton et al. 2007; Morriss et al. 2007; Moorcroft et al. 2010).

In August 2005 on the Seychelles Islands, Gideon Climo (pers. comm.) undertook three 2 hour evening trapping sessions using six KMT prototype traps, which were systematically set, checked, cleared and rebaited with coconut on a rotational basis. He caught over 60 ship rats, achieving 100% humane head and neck strikes on the adults and predominantly shoulder and mid torso strikes on small rats.

The first Norway rat (R. norvegicus) caught in a KMT prototype was on Adak Island, Alaska in May 2006. The technician reported “a perfect kill just behind the eyes” and that the unprotected traps remained set and continued to catch after exposure to “gales whipping vegetation, deluges of rain and burial in snow” (Lisa Spitler pers. comm.).

On Wake Atoll in October 2007, BT and PD established a 200 x 200 m trapping grid for rats consisting of 100 traps spaced at 20 m. Fifty KMT prototypes formed a central core within the grid and were surrounded by 50 Catchmaster (CM) wooden based trigger traps modified to operate as “treadle” traps. Midway through the trial an extra 32 CM traps were added to the periphery, creating double trap sets on three sides of the grid. All traps were tacked to plywood base boards, placed unprotected on the ground and baited with cubes of fresh coconut. The grid was checked and serviced morning and late afternoon, totalling 13 check periods over 7 days. Wake had a high density rat population and a total of 549 rats (520 R. exulans and 29 R. tanezumi) were caught ─ 297 from 650 individual KMT trap checks and 252 from 810 individual CM trap checks. KMT traps scored 157 head/neck strikes to 125 body strikes, whereas CM traps scored 94 head/neck strikes to 152 body strikes and both trap types recorded low numbers of limb and tail strikes. Non-catch interference also varied between trap types, with KMT recording 85 traps sprung/empty and 13 traps set/bait missing, compared to CM with100 traps sprung/empty and 172 traps set/bait missing. Hermit crabs were the only non-targets caught, 6 in KMT and 22 in CM (BT & PD unpublished data). Clearly the KMT traps out-performed the CM traps on Wake, scoring higher catch rates to trap check ratios and a greater percentage of head and neck strikes. The considerable disparity in trap set/bait missing totals is hugely significant, especially since

it was mechanical malfunction (rectified in seconds with a file) that caused the problem in the small number of KMT traps afflicted whereas learned avoidance behaviour by rats was the cause with the CM traps.

From 2007-2010, KMT prototype traps were used in ecological surveys on New Caledonia, Wallis and Futuna Islands (Theuerkauf et.al 2010) and in trials to test the efficacy of unprotected KMT traps against “Ezeset” wooden based trigger traps on Pacific, ship, and Norway rats (Theuerkauf et.al 2011). These studies concluded from C. 2900 trap nights that KMT traps were the more effective against rats > 100 g (i.e. predominantly ship and Norway rats), whereas “Ezeset” traps were more effective against rats < 100 g (predominantly Pacific rats). A high percentage of “Ezeset” traps were sprung by heavy rain but rain had no effect on the KMT traps, which maintained a significantly higher percentage of operational traps throughout the trials. The durability of the KMT traps was considered an advantage for long term field use.

The “safeTcatch” rat trapThe first commercial KMT trap to be produced was the

“safeTcatch” (“sTc”) rat trap (Fig. 2), which incorporates a safe set mechanism and is currently available from KMT Ltd, Nelson, NZ. The traps are constructed from extruded aluminium with stainless steel shafts and fasteners and double sprung with galvanised springs. Bar catches that engage when arming the trap work in conjunction with the wide retainer arm that automatically releases the safety

Fig. 1 Relative condition of Ka Mate prototype (left) and Victor Professional (right) after equal environmental exposure at adjacent sites in the Big Bush trap trial. Fig. 2 Ka Mate “safeTcatch” trap - with trigger cowling and

wax bait.

Fig. 3 Typical humane head strike - ship rat in unprotected Ka Mate “sTc” trap.

235

catch during setting, which makes the process easier for those with weaker hand strength. The traps are supported with replacement parts, which means that KMT traps can be easily repaired, upgraded or converted as design of component parts develops to improve trigger configuration or to suit a different target species. Replacement of any part can be easily undertaken using a simple custom-designed trap tool, so there is no reason to discard a whole trap.

A detachable plastic trigger cowl forces rats to take the bait from the front of the trap, ensuring a humane head strike (Fig. 3) while reducing potential for learned trap avoidance. Baits held firmly beneath the curve in the trigger ensure the trap will not trigger prematurely when knocked or when non-target species such as lizards, birds, or small mammals walk, crawl, or bounce on the trigger. Since it requires a concerted effort by the rat to remove the bait from beneath the trigger (which can cause the trap to move), it is essential that the trap be restrained for maximum efficiency. Holes are therefore provided in the base for spikes, screws or ties, which enable it to be secured to a backing board or either horizontally or vertically to a natural substrate. The operational stability inherent in the design of the trap (especially the trigger function) reduces spontaneous misfire and by-catch and the simple trap setting procedure minimises operator bias between trappers.

Ka Mate “flat-pack” protective station Protective covers are used with traps to restrict entry by

non-target fauna and to protect the baits, but many covers in use are bulky, heavy, flimsy or difficult to access. Ka Mate has produced a trap station fabricated in one-piece from “Corflute” cellular plastic sheeting. KMT “flat pack” stations fold compactly for storage and transport and have a lid that provides easy access (Figs. 4 and 5).

The stations have entrances on each side at one end for rats and centrally placed for mice, which provide alternative avenues for entry or escape and create a 90 degree entry angle that reduces the reach of non-target birds. When stations are fixed with stakes or weighted with rocks on the side flaps, target species can enter and walk up to the trap on natural substrate. Decomposing carcases suppurate directly into the ground. Alternatively, KMT stations and traps can be screwed vertically onto trees/posts/walls at a height that allows target species easy access. When set vertically, the rats are confined to a smaller floor space, preventing pull back as the trap triggers and enhancing catch effectiveness (Fig. 5).

Bait development The bait is crucial to the function of Ka Mate traps and

requires removal by a positive twist or tug to extract it from beneath the trigger to spring the trap. Rodents invariably take baits by mouth, which ensures the animals’ head is in an optimum position to achieve an efficient fatal head strike. Bait can be household food items, such as hazel nuts, brazil nuts, walnuts, dog and cat pellets, chocolate, dried cheese and cubes of fresh coconut, or any other food firm enough to support the downwards pressure of the trigger. KMT has also developed and tested purpose-built baits using “Pestoff” non-toxic pre feed (Animal Products, Wanganui) as a base ingredient. When mixed into palm nut wax with different flavoured additives, the baits can be moulded into plugs of optimum shape and size to fit the KMT trigger (Fig. 2). These baits can be effective for up to a month in dry conditions, but earlier replacement is recommended.

Utilisation and user perception When the Ka Mate “sTc” trap became available in

June 2008, prospective users such as community trapping groups began undertaking trials to test the new traps. They invariably set up proximately paired and/or alternating trap trials with Victor Professional traps and early anecdotal feedback indicated some disappointment over KMT trap performance. The issues apparently arose from long established practices associated with the operation of traditional snap traps, which were problematic when universally applied to Ka Mate traps. For example, trappers assumed that baits placed under the extreme end of the KMT trigger would be easier to remove (i.e. the equivalent of hair triggering old style traps) and consequently improve “sTc” trap performance. The practice instead exacerbated the incidence of rats beating the striker, being injured by a glancing blow or caught by a limb. It also increased the chance of catching non-target species. Furthermore, trappers often did not appreciate that the curved “sTc” trigger that accommodates the bait is specifically designed to slow rats down by forcing them to twist the bait sideways to remove it, ensuring the head is in optimum position to receive an efficient cranial strike.

Thomas et al.: Ka Mate snap trap

Fig. 4 Corflute “flatpack” trap-station (assembled for use and folded for storage). Fig. 5 Vertically set “flatpack” station with the door open.

Island invasives: eradication and management

236

Similarly, when several users complained that their KMT traps were not achieving high catch rates, it transpired that during service checks any traps found still set were bypassed, with many baits unchanged for two or three months. Contrary to common belief, rodents do not like stale mouldy food and it is imperative that the bait on KMT traps be replaced regularly.

Also, people placed new sterile KMT traps alongside pre-used odour saturated treadle traps, creating an obvious disadvantage for the KMT traps because of rats’ inherent nervousness around new equipment. Neophobic behaviour combined with differences in trap function (e.g., the arbitrary depression of the treadle foot-plate vs conscious, controlled reverse-trigger bait removal) tended to skew the trials into a “race” to see which trap would catch the same rat first. Trap catch data and observations made on several occasions indicates that in most instances (unless there is intense competitive pressure) it takes much longer for rats to trigger a KMT trap than a large-plate treadle trap. Rats have been seen to cautiously approach baited

KMT traps several times, often from different angles, before even putting a foot on them and they sometimes departed altogether for several hours or overnight before returning to check out a trap again. As their confidence grew, they would on occasion mouth the bait several times or nibble it a little before making the fatal decision to take a firm hold and twist or pull it from beneath the trigger (BT, RT, PD and Gideon Climo pers. obs., Baki Bakhshi video recording). Many trappers fail to understand that the most important function to test for in a new trap is not how quickly it catches rats, but how effectively it kills them.

Since results from several of the field trials raised issues with regard to the validity of proximal paired testing, we considered a well planned, large scale trial was needed to test the efficacy of the commercially produced KMT “safeTcatch” rodent traps in isolation of other brands. An opportunity for a major collaborative “trap trial by management” arose in late 2008 using “sTc” traps for rat control in a private eco-restoration project in Northern Coromandel.

Fig. 6 Waiaro grid layout and Year 1 tracking-tunnel results.

237

WAIARO SANCTUARY TRAPPING PROGRAMME

Waiaro Sanctuary is private land in the Moehau Kiwi Recovery zone, Moehau Forest, ten kilometres north of Colville. The first phase goal of this new rodent trapping programme was to achieve a toxin-free eradication of ship rats, or to reduce and hold their densities at low levels (5-10% tracking tunnel indices) over a 75 ha block, using only KMT traps.

A 75 ha grid was created with 427 single “sTc” rat traps at 25 m intervals along 10 trap lines spaced 75 m apart, with a perimeter line set along three sides of the grid (Fig 6). Fifty of the perimeter traps were in protective KMT “flatpack” stations. The rest of the traps were fitted with plastic trigger cowls and secured, uncovered, by being pinned to the ground or tied to tree roots. Five index lines (10 tracking tunnels per line) were installed to independently monitor trapping success, three within the grid and two outside (Fig 6).

Traps were given time to weather and three applications of Pestoff RS5 nontoxic pre-feed was hand broadcast sequentially across the block, along trap lines and then in close proximity to the traps only. The traps were then set using KMT RS5 wax plug baits.

Fifteen full checks with all traps serviced in a 24-48 hr period were completed in the 12 months from 22 January 2009 to 21 January 2010, the majority in the first 6 months. Alternatively, progressive servicing was carried out line by line over periods of a week to a month and in winter service checks were restricted to perimeter lines only. Head and neck strikes on adult rats were so consistent that the field teams stopped recording the category, insisting that the KMT traps were achieving “99%” humane kills, including body blows to smaller rats (KM pers. obs.). Four index tracking sessions were undertaken both inside and outside the trapped area - two prior to trapping and two during trapping.

The traps caught 656 rats, with index tracking frequencies reduced from up to 100% before trapping to 10% during the trapping period (Fig 6). An initial knockdown of 299 rats was achieved in less than three weeks with tallies rising to 558 at three months. A further 98 rats were caught during the next nine months with 15 of these in the six weeks before the final January 2010 check (Fig. 7) - a marked contrast to the 117 caught on night one 12 months earlier. The reduction of rats was substantial and only one bird (not identified) and 81 mice were the by-catch from one year’s trapping (approx 90,000 trap nights) in Waiaro Sanctuary with unprotected traps.

The RS5 wax plugs remained intact for more than a

month, but probably lost their attractiveness as bait for rats much sooner. Operators found the KMT stations convenient to install and access, and the traps easy to operate and service.

DISCUSSION

Varied outcomes from the early field trials made it difficult to determine what advantages the KMT prototypes provided over the traditional trigger and treadle traps. As the data base grew we began to speculate that rat behaviour coupled with trap function was elemental to the different catch rates being recorded between the trap types, the main contributing factor being that it took rats longer to spring a KMT trap than a traditional trigger or treadle trap. The dense population of Pacific rats on Wake Atoll coupled with the use of night vision equipment (plus the mass of data this project generated) and Gideon Climo’s trapping of ship rats in the Seychelles provided the first opportunities to evaluate rat behaviour in conjunction with KMT trap function from direct observation. Although we have drawn our conclusions from all the studies, it is the significant level of rat control achieved with Ka Mate traps in Waiaro Sanctuary that verifies its potential when used alone, unencumbered by the proximity of other trap types (Fig. 7).

The functional stability of the reverse-bait trigger generates a very consistent catch performance. The percentage of quality-kill head and neck strikes can be increased and environmentally generated misfire, rodent induced trap disturbance, and non-target by-catch significantly reduced when using KMT traps. Such results minimise the opportunities for rats to learn trap avoidance and reduces animal welfare issues. The simple standard setting procedure of KMT traps eliminates operator bias and improves population indexing.

The functional stability of KMT traps coupled with trap durability enables traps to be screwed vertically onto bulkheads in ships and permanently fixed inside containers or onto wharves. KMT traps can easily be cleaned and sterilised for bio-security purposes by boiling and are robust enough to operate with minimum maintenance in estuarine and marshland environments. They could be hoisted into trees to sample for rodents in forest canopies or provide protection to hole nesting birds, and are safe enough to be set in many situations where use of other traps would pose a risk to vulnerable non-target species.

In New Zealand, increasing numbers of community groups vie for the same resources to set up predator control programmes and many established projects are continually expanding the areas already being trapped. Development of effective long-life bait will be the key for using traps instead of toxicants to control rats in mainland situations, or for long term surveillance on islands. As trapping technology and deployment improves, wider spacing and less frequent servicing may make it possible to manage larger areas for the same capital outlay, but care must be taken to get the strategy right.

ACKNOWLEDGMENTS

We are indebted to Bernard Goetz for engineering advice and for fabricating the steel prototypes, to Jean Fleming and Mary McEwen for the grant received from the C.A. Fleming Trust and Alan Hall who made the “Weka Bush” trial traps, but wouldn’t send a bill. Matt Maitland and Dan Baigent organised the pilot trials with Department of Conservation support and Manaaki Whenua Landcare Research provided financial assistance for the independent report. To Gideon Climo and Jörn Theuerkauf for sharing valuable results from their trap trials in the tropics and Katie Swift (USFWS), US Air Force and our Wake Atoll

Thomas et al.: Ka Mate snap trap

Fig. 7 Waiaro trapping - comparative totals of rats caught by period.

Island invasives: eradication and management

238

survey colleagues for the opportunity to run the airfield trapping grid. To Dion and Caren Paul (cofounders of Ka Mate Traps Ltd) for the company name, logo and generosity when moving on to bigger things and Fuka (Liu Xuezheng “Allen” and Shi Cheng “Johnson”) for their patience and producing a quality product. The Biodiversity Condition Fund team provided advice and funding to Waiaro Sanctuary, and to neighbours for their cooperation and input into the project. To supportive friends such as Ken Lipsmeyer, Ruth and Lance Shaw, Ron and Robynne Peacock, Richard van den Berg and Richard Daem, Anna Clark and numerous colleagues in science and conservation circles who have provided help and encouragement over many years, and more recently the Ka Mate trap users who have provided feedback and useful suggestions. To Keith Broome, John Innes and another reviewer who made suggestions that improved the manuscript and Dave Towns and Dick Veitch for editorial improvements. But not least we acknowledge Pam and the long suffering Thomas whanau for their vital role in the development of Ka Mate Traps and this paper – arohanui ki a koutou katoa.

REFERENCESBailey C.I. and Eason C.T. 2000. Anticoagulant resistance in rodents.

Conservation Advisory Science Notes 297, Department of Conservation, Wellington, New Zealand.

Bull, P.C. 1946. Notes on breeding cycle of the thrush and blackbird in New Zealand. Emu XLVI: 198-208.

Daniel, M.J. 1973. Seasonal diet of the ship rat (Rattus r. rattus) in lowland forest in New Zealand. Proceedings of the New Zealand Ecological Society 21: 21-30.

Dunlevy, P.; Campbell, E.W. and Lindsey, G.D. 2000. Broadcast application of a placebo rodenticide bait in a native Hawaiian forest. International Biodeterioration and Biodegradation 45: 199-208.

Efford, M.G.; Fitzgerald, B.M.; Karl, B. J.and Berben, P.H. 2006. Population dynamics of the ship rat Rattus rattus L. in the Orongorongo Valley, New Zealand. New Zealand Journal of Zoology 33: 273-297.

Howald, G.; Donlan, C.J.; Galvan J.P.; Russell, J.C.; Parkes, J.; Samaniego, A.; Wang, Y.; Veitch, R.; Genovesi, P.; Pascal, M.; Saunders, A. and Tershy, B. 2007. Invasive rodent eradication on islands. Conservation Biology 21(5): 1258-1268.

Innes, J.; Warburton, B.; Williams, D.; Speed, D. and Bradfield, P. 1995. Large-scale poisoning of ship rats (Rattus rattus) in indigenous forests of the North Island, New Zealand. New Zealand Journal of Ecology 19(1): 5-17.

Litten K.E.; Mellor D.J.; Warburton B. and Eason C.T. 2004 Animal welfare and ethical issues relevant to the humane control of vertebrate pests. NZ Veterinary Journal 52(1): 1-10.

MacKay J.W.B. and Russell J.C. 2005. Ship rat Rattus rattus eradication by trapping and poison-baiting on Goat Island, New Zealand. Conservation Evidence 2: 142-144.

Malcolm T.R.; Swinnerton K.J.; Groombridge J.J.; Sparklin W.D.; Brosius C.N.; Vetter J.P. and Foster J.T. 2008. Ground-based rodent control in a remote Hawaiian rainforest on Maui. Pacific Conservation Biology 14: 206-214.

Mason, G. and Litten, K.E., 2003. The humaneness of rodent pest control. Animal Welfare 2003, 12: 1-37.

Merton, D.; Climo, G.; Laboudallan, V.; Robert, S. and Mander C. 2002. Alien mammal eradication and quarantine on inhabited islands in the Seychelles. In: Veitch, C.R. and Clout M.N. (eds.). Turning the tide: the eradication of invasive species, pp. 182-198. IUCN SSC Invasive Species Specialist Group. IUCN, Gland, Switzerland and Cambridge, U.K.

Moorcroft, G. (ed.); Baigent, D.; Barsdell, J.; Gebert, S.; Glaser, A.; Gorman, N.; Haxton, J.; Livingston, P.; Loughlin, L.; Wilson, D. and Wilson, L. 2010. Te Urewera Mainland Island Annual Report: July 2005 – June 2006. Department of Conservation, Rotorua. 52 pp.

Moors, P. 1985. Eradication campaigns against Rattus norvegicus on the Noises Islands, New Zealand, using brodifacoum and 1080. In: Moors, P.J. (ed.) Conservation of island birds, pp. 143-155. International Council for Bird Preservation, Technical Publication 3, Cambridge, U.K.

Morriss, G.; Warburton B. and Forrester G. 2007. Efficacy of the Ka Mate rat trap. Landcare Research Contract Report LC0607094, Lincoln, New Zealand.

Morrell, T.E.; Ponwith, B.; Craig, P.C.; Ohashi, T.J.; Murphy, J.G. and Flint, E. 1991. Eradication of Polynesian rats (Rattus exulans) from Rose Atoll National Wildlife Refuge, American Samoa. Appendix 3. DMWR Biological Report Series, No 20. Department of Marine and Wildlife Resources, Pago Pago, American Samoa.

Nugent, G.; Morgan, D.R.; Sweetapple, P. and Warburton, B. 2007. Developing strategy and tools for local elimination of multiple pest species. In: Witmer, G.W.; Pitt, W.C. and Fagerstone, K.A. (eds.). Managing vertebrate invasive species, pp. 410-417. Proceedings of an International Symposium, USDA/APHIS/WS, National Wildlife Research Centre, Fort Collins, U.S.A.

Ogden, J. and Gilbert J. 2008. Prospects for the eradication of rats from a large inhabited island: community based ecosystem studies on Great Barrier Island, New Zealand. Biology Invasions 11(7): 1705-1717.

Paton, B.R.; Maitland, M.J.; Bruce, T.A.; Wotherspoon, J.A.; Brow, A.K.; Leggett, S.A. and Chisnall, D.T. 2007. Rotoiti Nature Recovery Project Annual Report: July 2005 – June 2006. Occasional Publication No. 71. Department of Conservation, Nelson, New Zealand.

Powell, R.A. and Proulx, G. 2003 Trapping and marking terrestrial mammals for research: integrating ethics, performance criteria, techniques, and common sense. ILAR Journal 44(4): 259-276.

Saunders, A.J. 2000. A review of Department of Conservation mainland restoration projects and recommendations for further action. Department of Conservation, Wellington, New Zealand, 219 pp.

Saunders, A. 2003. New Zealand “mainland islands”: ecological restoration through intensive multi-pest control. Aliens 17. Invasive Species Specialist Group of the IUCN Species Survival Commission,.

Speedy, C.; Day, T. and Innes, J. 2007. Pest eradication technology – the critical partner to pest exclusion technology: the Maungatautari experience. In: Witmer, G.W.; Pitt, W.C. and Fagerstone, K.A. (eds.). Managing vertebrate invasive species, pp. 115-126. Proceedings of an International Symposium, USDA/APHIS/WS, National Wildlife Research Centre, Fort Collins, U.S.A.

Taylor, R. H.; Kaiser, G.W. and Drever, M.C. 2000. Eradication of Norway rats for recovery of seabird habitat Langara Island, British Columbia. Restoration Ecology 8: 151-160.

Theuerkauf, J.; Jourdan, H.; Rouys, S.; Gula, R.; Gajewska, M.; Unrug, K. and Kuehn, R. 2010. Inventory of alien birds and mammals in the Wallis and Futuna Archipelago. Biological Invasions 12(9): 2975-2978.

Theuerkauf, J.; Rouys, S.; Jourdan, H. and Gula, R. 2011. Efficacy of a new reverse bait trigger snap trap for invavsive rats and a new standardised abundance index. Annales Zoologici Fennici 48: in press.

Thomas, B.W. and Taylor, R.H. 2002. A history of ground-based rodent eradication techniques developed in New Zealand. In: Veitch, C.R. and Clout M.N. (eds.). Turning the tide: the eradication of invasive species, pp. 301-310. IUCN SSC Invasive Species Specialist Group. IUCN, Gland, Switzerland and Cambridge, U.K.

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.

Towns, D.R.; Atkinson, I.A.E. and Daugherty, C.H. 2006. Have the harmful effects of introduced rats on islands been exaggerated? Biological Invasions 8(4): 863-891.

Varnham, K. 2010. Invasive rats on tropical islands: their history, ecology, impacts, and eradication. RSBP Research Report No. 41, 45pp. Royal Society for the Protection of Birds, Sandy, Bedfordshire, U.K.

Watson, J.S. 1956. The present distribution of Rattus exulans (Peale) in New Zealand. New Zealand Journal of Science and Technology 37(5): 560-570.

Williams, J.M. 1994 Food and fibre markets and societal trends: implications for pest management. In: Seawright A.A.; Eason C.T. (eds.). Proceedings of the Science Workshop on 1080. The Royal Society of New Zealand Miscellaneous Series 28: 20-32.

Witmer, G.W. and Burke, P.W. 2007. Management of invasive vertebrates in the United States: an overview. In: Witmer, G.W.; Pitt, W.C. and Fagerstone, K.A. (eds.). Managing vertebrate invasive species, pp. 332-337. Proceedings of an International Symposium, USDA/APHIS/WS, National Wildlife Research Centre, Fort Collins, U.S.A.

Wodzicki, K.A. 1950. Introduced mammals of New Zealand: an ecological and economic survey. Department of Scientific and Industrial Research Bulletin 98. 255pp.

Wodzicki, K. 1969. Preliminary report on damage to coconuts and on the ecology of the Polynesian rat (Rattus exulans) in the Tokelau Islands. Proceedings of the New Zealand Ecological Society 16: 7-12.