Proceedings of the Vertebrate Pest Conference

Goodnature Ltd. humane self-resetting kill traps are being developed in New Zealand for use in animal pest control to protect nature conservation values. Two models are commercially available: the Goodnature Ltd. A12™ trap for common brushtail possums and the Goodnature Ltd. A24™ trap for rats and stoats. These species are significant animal pests in New Zealand, contributing to the decline of biodiversity and extinction of native species. Large amounts of conservation effort and resources are targeted at their control and elimination. Current best-practice trapping techniques include the use of single-action possum and rat traps. The A12 and A24 traps have the advantage over the existing single-action traps in that they self-reset. They are powered by compressed carbon dioxide and humanely kill individual animals by striking their skulls, producing instant irreversible unconsciousness. Dead animals clear the trap by falling away; the trap automatically resets, up to 12 times for the A12 and up to 24 times for the A24. This study presents the results of three preliminary field trials that evaluate the effectiveness of these traps as tools in the control of possums and rats. Using 0.75 A12 traps per ha in a 256-ha block at Pouiatoa Conservation Area, we achieved a Residual Trap Catch Index (RTCI) for possums of 5.7%, down from 15%, after 15 months. This RTCI was comparable with the level of control previously achieved using hand-laid cyanide baits, and close to the desired conservation target of 5%. At Ohane, we deployed 290 A12 traps over 476 ha (0.6 traps per ha) and achieved a reduction in RTCI from 22.6% to 6.8%. Field trials for the A24 trap were conducted in a 46-ha block at Rimutaka Forest Park with 1.72 traps per ha. The minimum number of rats caught per trap night declined sharply from 0.15 from the first trapping period to 0.01 after the second trapping period, and remained below 0.03 for the entire 4-month trap trial. The New Zealand Department of Conservation is presently conducting several large-scale operational field trials for both traps.