The tree species preferences of koalas (Phascolarctos cinereus) inhabitingforest and woodland communities on Quaternary deposits in the Port Stephens area, New South Wales

An assessment of the tree species preferences of koalas inhabiting forest a nd woodland communities growing on Quaternary deposits in the Port Stephens area, New South Wales, was undertaken between November 1994 and March 1996 . Using a plot-based methodology, 3847 trees were sampled, comprising 15 Eu calyptus species and 17 species of non-eucalypt. Evidence of tree use by ko alas, specifically the presence of koala faecal pellets, was recorded from beneath 10 Eucalyptus species and 9 species of non-eucalypt. Tree species p references were determined by analyses of log-likelihood ratios derived fro m data based on the presence/absence of koala faecal pellets, rather than o n gross counts. This approach confirmed significant variation in the levels of utilisation amongst and between different tree species, and that two in particular - swamp mahogany (E. robusta) and drooping red gum (E. parramat tensis) - were most preferred. Increases in the levels of use of other tree species were also positively associated with the presence of E. robusta an d/or E. parramattensis. Levels of utilisation of E. robusta and E. parramat tensis did not alter significantly in response to changes in their respecti ve densities, suggesting that the relative abundance of both was important in terms of understanding the carrying capacity of vegetation communities u tilised by koalas. The results have established the success with which an e numerative approach to the interpretation of faecal pellet data can be util ised to clarify the tree species preferences of koalas. Application of the approach for habitat assessment and mapping purposes is also discussed.