The Ka Mate Reverse-Bait Snap Trap – a Promising New Development
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Thomas, B.; R. Taylor, P. Dunlevy, K. Mouritsen, and J. Kemp. The Ka Mate reverse-bait snap trap – a promising new development 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. <[email protected]>. 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. INTRODUCTION Advances worldwide in rodent control or eradication comm.). Poor trap performance has exacerbated negative on islands during the past three decades have centred on public attitudes, resulting in stricter rules for trapping and the use of rodenticides (Howald et al. 2007). However, the animal welfare now embedded in policy and law (Mason propensity for rodents to develop a tolerance for toxicants and Litten 2003; Powell and Proulx 2003; Litten et al. (Bailey and Eason 2000) and increasing public opposition 2004). to use of poisons may limit their continued use, particularly Traps have traditionally varied from toggle trigger traps in mainland situations (Williams 1994; Towns and Broome with a small (baited) trigger to large treadle plate designs 2003; Mason and Littin 2003; Towns et al. 2006). Traps that use a lure to entice target species to step onto a plate to have similarly evolved in design and strategic use but they spring the device. Treadle snap traps are generally easier to also attract a public opposition, ostensibly over animal use than trigger traps. Many trap designs are operationally welfare issues. unstable and not robust enough to withstand the rigours of The New Zealand Department of Conservation long term field use. Baseboards on wooden models warp (DOC) requires a better performing snap trap that gives or split, staples pull and weak points on plastic variations more consistent catch/kill rates; improved animal welfare soon break. The larger trigger area of treadle traps makes outcomes; less non-target catch and environmental them more prone to misfire due to environmental events interference; enable higher quality trapping data; have and the presence of non target species. greater durability; less maintenance; quicker servicing during routine checks; and are easier for operators to use THE KA MATE REVERSE-BAITING SNAP TRAP than current preferred rodent traps. In short, better returns from traps in relation to money expended (Keith Broome Trap development pers. comm., April 2004). During the mid-1980s, two of us (RT and BT) In this paper, we describe the development and field experimented with ways to improve snap trap efficiency. trials of Ka Mate (KMT) reverse-bait snap traps, which Modifications were made to wooden based trigger “Ezeset” have been designed to meet modern efficacy and animal traps being used to catch Norway rats (Rattus norvegicus) welfare requirements. which led to “reverse-baiting” snap traps with dense, supportive bait beneath rather than on top of the trap trigger. Traditional, wooden based “break-back” traps (snap This utilised the bait as a removable structural component traps), have been used in New Zealand since at least 1920, of the trap, introducing significantly more stability into the particularly for bio-security at ports, rodent control around trigger function. factories, and as a health measure in urban environments (Wodzicki 1950). They have also been used internationally Six steel reverse-bait snap traps were then engineered for scientific data collection and in conservation management in 2003 and of the five ship rats Rattus( rattus) these first programmes (Bull 1946; Watson 1956; Wodzicki 1969; killed, three were cranial and two were humane neck strikes. Daniel 1973; Innes et al. 1995; Dunlevy et al. 2000; Efford Fifty of these traps were subsequently incorporated into a 6 et. al. 2006; Malcolm et al. 2008; Theuerkauf et al. 2010). month paired trial with “Victor Professional” traps at Weka More recently, snap traps have been employed in many Bush, Nelson Lakes National Park. In 2005, 100 handmade large-scale New Zealand mainland island rodent control aluminium prototypes (Fig. 1), which we called Ka Mate programmes (Saunders 2000, 2003; Speedy et al. 2007; (KMT) traps, were integrated with the steel traps into an Ogden and Gilbert 2008) and as adjuncts to toxicants in alternating trap trial with “Victor Professional” rat traps island eradication campaigns (Morrell et al. 1991; Taylor and tested over 13 months in Nelson Lakes Big Bush rodent et al. 2000; Merton et al. 2002; Thomas and Taylor 2002; control area. Another 100 KMT prototypes were included MacKay and Russell 2005; Nugent et al. 2007; Witmer and in an alternating trap trial with Victor Professional rat traps Burke 2007; Varnham 2010). in DOC’s 2005 trap research programme in Te Urewera National Park. Rats have been eradicated from at least two islands of up to 21 ha with snap traps (Moors 1985; MacKay and The KMT traps caught and killed mice (Mus musculus), Russell 2005; Howald et al. 2007), but trapping is usually rats (Rattus rattus), weasels (Mustela nivalis), stoats considered to be too labour intensive and expensive as a (M. erminea) and hedgehogs (Erinaceus europaeus). In sole eradication technique for rats (Keith Broome pers. the Te Urewera trial, the KMT traps also had far fewer Pages 233-238 In: Veitch, C. R.; Clout, M. N. and Towns, D. R. (eds.). 2011. Island invasives: eradication and management. IUCN, Gland, Switzerland. 233 Island invasives: eradication and management 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. unsprung/bait missing events than Victor traps (2 versus 71, respectively), indicating that the reverse-bait trigger it was mechanical malfunction (rectified in seconds with a reduced problems with non-target and environmental file) that caused the problem in the small number of KMT triggering. When compared with wooden-based wire striker traps afflicted whereas learned avoidance behaviour by rats traps, operators also found the aluminium KMT to be the was the cause with the CM traps. safest to set and handle, easiest to clean and maintain (Fig. From 2007-2010, KMT prototype traps were used in 1), required the least service time during routine checks, ecological surveys on New Caledonia, Wallis and Futuna and had the greatest durability in the field (Paton et al. Islands (Theuerkauf et.al 2010) and in trials to test the 2007; Morriss et al. 2007; Moorcroft et al. 2010). efficacy of unprotected KMT traps against “Ezeset” In August 2005 on the Seychelles Islands, Gideon wooden based trigger traps on Pacific, ship, and Norway Climo (pers. comm.) undertook three 2 hour evening rats (Theuerkauf et.al 2011). These studies concluded trapping sessions using six KMT prototype traps, which from C. 2900 trap nights that KMT traps were the more were systematically set, checked, cleared and rebaited effective against rats > 100 g (i.e. predominantly ship and with coconut on a rotational basis. He caught over 60 ship Norway rats), whereas “Ezeset” traps were more effective rats, achieving 100% humane head and neck strikes on the against rats < 100 g (predominantly Pacific rats). A high adults and predominantly shoulder and mid torso strikes percentage of “Ezeset” traps were sprung by heavy rain on small rats. but rain had no effect on the KMT traps, which maintained The first Norway rat (R. norvegicus) caught in a KMT a significantly higher percentage of operational traps prototype was on Adak Island, Alaska in May 2006. The throughout the trials. The durability of the KMT traps was technician reported “a perfect kill just behind the eyes” and considered an advantage for long term field use. that the unprotected traps remained set and continued to catch after exposure to “gales whipping vegetation, deluges The “safeTcatch” rat trap of rain and burial in snow” (Lisa Spitler pers. comm.). The first commercial KMT trap to be produced was the On Wake Atoll in October 2007, BT and PD established “safeTcatch” (“sTc”) rat trap (Fig. 2), which incorporates a 200 x 200 m trapping grid for rats consisting of 100 traps a safe set mechanism and is currently available from KMT spaced at 20 m. Fifty KMT prototypes formed a central core Ltd, Nelson, NZ. The traps are constructed from extruded within the grid and were surrounded by 50 Catchmaster aluminium with stainless steel shafts and fasteners and (CM) wooden based trigger traps modified to operate as double sprung with galvanised springs.