Brushtail possum (Trichosurus vulpecula) movement and removal success in the sea-cliff eco-systems of Banks Peninsula

Abstract

Brushtail possums (Trichosurus vulpecula) are well-recognized for their ability to inflict widespread damage on much of Aotearoa New Zealand's native flora and fauna, putting them firmly on the list of invasive species to be targeted for removal. However, there is little understanding of how the vegetative and topographical features of sea-cliff eco-systems influence their movements, and the subsequent impacts on control operations. With the instigation of the Predator Free New Zealand 2050 program, this becomes key information for each type of eco-system to achieve total and complete eradication nationwide. This project focuses on the influence of habitat in this particular environment, how this impacts possum movements and home-ranges in comparison to current understanding in other types of eco-systems such as dryland pasture or forest eco-systems. Alongside Pest Free Banks Peninsula, attention was turned to how best to eradicate this invasive pest species in a landscape that provides significant topographical challenges. GPS tracking collars will be used to evaluate possum movement and habitat use, then uniquely marked mortality collars and cameras will determine the success of a ground-based bait station operation in removing this population. Encounter-interaction rates, bait take, how these both change over time, as well as estimated population removal percentage will all be used to help determine operational success. We predict that the project results will be able to inform organizations such as Pest Free Banks Peninsula whether ground-base bait station operations will provide the outcomes they require, and to identify areas that would benefit from further investigation.