Do Possum (Pseudocheirus occidentalis; Trichosurus vulpecula hypoleucus) Counts Vary with the Time of the Survey?
Royal Society of Western Australia Inc.
Faculty of Business and Law
Faculty Office (FBL) / Centre for Ecosystem Management
Western Ringtail Possums (Pseudocheirus occidentalis) are listed as conservation significant species with both State and Commonwealth governments. As a consequence any areas proposed for development that potentially support these possums are surveyed to determine their abundance. Here we report a decline in the number of P. occidentalis recorded for successive surveys during the same night suggesting that some individuals either retreat to areas where they are not visible or observer fatigue results in fewer possums being detected. In contrast, there was no difference in the number of Common Brushtail Possums (Trichosurus vulpecula hypoleucus) observed during the same surveys. This finding has important consequences for environmental consultants or researchers that are undertaking multiple surveys during a night to record local population sizes for Western Ringtail Possums in Western Australia.