Changes to a population of common ringtail possums (Pseudocheirus peregrinus) after bushfire

Abstract

Following bushfires in Sydney in 1994 a population of 20–30 common ringtail possums (Pseudocheirus peregrinus) that had been studied for four years was reduced to only one or two animals. In the intervening years population numbers remained at this low level. Four years after the fire, 22 ringtail possums were introduced into the study site and radio-tracked for 30 weeks. Nest usage shifted from predominantly dreys before the fire to an equal amount of time spent in dreys and tree hollows. Proportionally, the mortality due to predation by lace monitors (Varanus varius) and diamond pythons (Morelia spilota spilota) increased. Within 12 months the population returned to only two animals. We conclude that increased predation by native predators, added to continued predation by foxes and cats, has maintained a level of predation beyond a threshold that would allow the ringtail population to re-establish to previous levels.