The conservation of arboreal marsupials in the montane ash forests of the central highlands of Victoria, south-eastern Australia, VI. The performance of statistical models of the nest tree and habitat requirements of arboreal marsupials applied to new survey data

Statistical models are widely used as a tool to provide a concise description of data by identifying and quantifying relationships between key explanatory variables. The adequacy of the fit of such models to the data can be gauged by various diagnostic procedures. However, the performance of statistical models, when applied to new datasets, can yield valuable insights about the various assumptions that underpin such models and may identify potentially important new explanatory variables. In this study we describe the results of a field survey that was undertaken specifically to assess the performance of previously developed statistical models of the nest tree and habitat requirements of arboreal marsupials inhabiting the montane ash forests of the central highlands of Victoria, south-eastern Australia. The study involved comparing logit and Poisson regression models developed from surveys at 152 sites completed between 1983 and 1989 with a new dataset comprised of 55 sites that was gathered in 1992-1993. Our analyses demonstrated that most of the models developed in earlier studies performed reasonably well when they were applied to the recently collected data. Thus, for the two datasets, there were similarities in the statistical relationships between characteristics of trees with hollows and their occupancy by various species of arboreal marsupials. Similar results were recorded from assessments of the performance of the habitat models. Notably, for some species such as Leadbeater's possum, Gymnobelideus leadbeateri McCoy, there was greater congruence between the results of the two surveys than recorded in similar comparisons with data collected from retained linear strips (wildlife corridors). This finding further emphasizes previous observations that the species appears to be disadvantaged in narrow areas of linear habitat.