Kiwi-safe kill traps for possums

Trappers in New Zealand have traditionally used ground-set leg-hold traps to catch possums (Trichosurus vulpecula) but these sets also occasionally catch kiwi (Apteryx spp.) and weka (Gallirallus australis). To prevent the trapping of these birds, the Department of Conservation (DoC) requires all traps to be placed 70 cm above the ground in areas with kiwi and weka. To set leghold traps at this height, additional materials need to be carried, such as platforms or boards, and this reduces trapper efficiency. An alternative approach which has the potential to improve trapper efficiency and address welfare concerns due to leg-hold trapping is to use kill traps set on tree trunks 70 cm above the ground. Two trunk-set kill-trap types (BMI 160 and LDL 101) were tested for possum capture efficiency and compared with ground-set Victor No.l unpadded leg-hold traps. Possum capture efficiencies were similar for both trunk-set kill traps but were much less than for ground-set leg-hold traps. However, capture efficiency of kill traps on a per visit basis could be increased if traps were left for several nights before being checked (assuming the pending animal welfare legislation will allow this). The BMI 160 kill trap has the potential to catch more possums than the LDL 101 kill trap, but animal welfare impacts appear greater in the BMI 160, with more possums escaping, being inhumanely caught, or not being killed quickly. Although the weight and size of the kill traps tested would not significantly impair trapper efficiency, both kill traps took longer to set than the ground-set leg-hold traps. We do not currently recommend the use of trunk-set kill traps by DoC possum control staff, as they do not provide a cost-effective alternative to leghold traps. However, improved setting methods of these kill traps might reduce the high number of escapes, sprung traps, and inhumane captures. Raised leg-hold trap sets should continue to be used for capturing possums in areas with kiwi and weka.