Abstract
The western ringtail possum (Pseudocheirus occidentalis) is classified as vulnerable on the Threatened Species List. Populations are diminishing due to habitat loss, particularly from building development in coastal regions of southwest WA. A translocation program is attempting to re-establish populations within the species' pre-European range. Survival of translocated possums was investigated in relation to pre-translocation health status, competition with common brushtail possums (Trichosurus vulpecula) and feral predator control measures. Mortality rates due to predation by both feral and native predators (cat, fox, and python) were high. Survival analyses using Information Theoretic techniques identified lymphocyte counts and brushtail possum population size as factors affecting survivorship. These results illustrate the need to take into account the complex nature of interactions between health, ecological factors and invasive species when managing a threatened marsupial.