A novel device for controlling brushtail possums (Trichosurus vulpecula)

Abstract

© New Zealand Ecological Society. Pen and small-scale field trials have been completed on a new, long-life, resetting toxin delivery system for brushtail possums (Trichosurus vulpecula). Devices are designed to attract and control possums over long periods of time with minimal input and maintenance. The units are species-specific, lightweight, environmentally robust, and have the ability to control 100 possums before requiring servicing. Devices dispense a measured dose (0.8 g) of a palatable gel containing 12.5% zinc phosphide (Zn₃P₂) onto a possum’s abdomen. Pen trial results demonstrated that after receiving a measured dose from these devices, 89% of nine possums groomed the gel from their fur, ingested it and died. The average time to death following ingestion of a lethal dose of zinc phosphide was 4.6 hours, a comparatively short timeframe compared to other control tools (specifically sodium fluoroacetate, cholecalciferol or brodifacoum). A small-scale field trial deploying 11 devices at 100-m intervals was run in an 11-ha mountain beech (Fuscospora cliffortioides) forest site. A sample of ten possums in the vicinity of these devices were collared with VHF-mortality sensors and, of the nine individuals with known fates, eight were killed shortly after interacting with a resetting delivery system.