Assessing the palatability of threatened plant species to possums

The introduction of brushtail possums (Trichosurus vulpecula) into a country previously without arboreal mammals has had a pervasive impact on New Zealand's indigenous ecosystems (Green 1984). Possums selectively browse palatable plant species, eliminating some while favouring those that are unpalatable. This results in a progressive change in the species composition of browsed vegetation associations. Measuring diet preferences of free-ranging animals is fraught with problems (Norbury & Sanson 1992), especially when the species concerned are rare or threatened. However, it is particularly important to establish the palatability of such species to possums, as this will help direct their future conservation management. In this report, we propose a method for assessing the palatability of selected threatened plant species using captive possums.This report was prepared as external unprogrammed science advice for Westland Conservancy, Department of Conservation