The south east mainland sub-species of spotted-tailed quoll (Dasyurus maculatus maculatus) was the subject of the present research with a focus on populations persisting in southern Queensland and the northern section of the New England Tableland bioregion. D. m. maculatus is the largest marsupial carnivore remaining on the mainland of Australia. The sub-species is listed as Endangered under national legislation and since European settlement has experienced a range retraction of 50-90%. Estimates indicate that only 10,000 or fewer individuals are now surviving in the wild. To contribute to the growing body of knowledge of wild spotted-tailed quoll populations the study investigated the distribution, detection, diet and population dynamics of quolls using hair funnels, live trapping and scat analysis. Population viability analysis modelling was used to predict the fate of a population. A search for quoll populations in the Southern Downs region of southern Queensland confirmed that the sub-species is now largely absent from the area with only one thriving population located at Cullendore. Extension of the search area into northern New South Wales indicated that a widely dispersed metapopulation potentially survives in the New England Tableland bioregion with its northern limits in southern Queensland and its southern limits south of Armidale. An initial assessment of the comparative abundance of quolls and introduced carnivores indicated that competitive and predatory interactions may outweigh benefits quolls derived from the presence of extensive areas of high quality habitat.