In such contexts, managers have long relied on experts to translate data and available evidence into advice (Sutherland, 2006). A quantitative, scientific method for deriving estimates of koala populations and trends was possible, in the absence of empirical data on abundances.įor many species, the available evidence in the form of field surveys and modelling capabilities to predict population numbers leaves gaps in the capacity to make timely conservation decisions. It was not necessary to achieve high levels of certainty or consensus among experts before making informed estimates. Estimated percentage of loss in Queensland, New South Wales, Victoria and South Australia was 53%, 26%, 14% and 3%, respectively. On the basis of estimates of mean population sizes for each bioregion and state, we estimated that the total number of koalas for Australia is 329,000 (range 144,000–605,000) with an estimated average decline of 24% over the past three generations and the next three generations.

We derived estimates of the mean population size of koalas and associated uncertainties for each bioregion and state. They provided their lowest plausible estimate, highest plausible estimate, best estimate and their degree of confidence that the true values were contained within these upper and lower estimates. Using a structured, four-step question format, a panel of 15 experts estimated population sizes of koalas and changes in those sizes for bioregions within four states. LocationĮastern and south-eastern Australia Methods Diverse opinions exist about estimates of abundance and, consequently, the status of populations. This study examined whether it is possible to use expert elicitation to estimate abundance and trends of populations of this species. The koala is a widely distributed Australian marsupial with regional populations that are in rapid decline, are stable or have increased in size.

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