population control

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.

This paper describes the impact of nine poison operations on ship rats in four areas (35 ha to 3200 ha) of North Island forest. Poisoning with 1080, brodifacoum, or pindone killed 87- 100% of rats, based on trapping and tracking-tunnel indices. Rat populations took 4-5 months to recover. Operations to protect nesting birds should therefore coincide with the onset of nesting and be rePeated each year, although not necessarily with the same methods.