Eastern pygmy possum (Cercartetus nanus) populations persist in Central Coast forests after the Black Summer bushfires

Abstract

The 2019–2020 Black Summer bushfires are an example of Australia’s climate-induced, changing fire regimes, where flora and fauna suffer both direct and indirect impacts as the result of large fires. The eastern pygmy possum (Cercartetus nanus) is a species that may be affected and, although its general ecology is well understood, there is limited knowledge of its response to wildfire. Using clusters of nest boxes across two state forests on the New South Wales Central Coast, detection histories were created from 2017 to 2023. Estimates of occupancy, detection and extinction were produced, where the top ranked model included Fire severity as a covariate of extinction. Extinction probability was highest in unburnt areas, 0.55 (95% CI = 0.13–0.82) and lowest in moderate fire severity areas, 0.15 (95% CI = 0.003–0.52), although all estimates were highly uncertain. Detection probability was 0.35 per cluster visit (95% CI = 0.26–0.45) and occupancy probability was 0.77 (95% CI = 0.39–0.98), indicating a high probability of occupancy at sites affected by fire. This suggests that eastern pygmy possums may benefit from post-fire resources, such as flowering shrubs, as well as their flexible den selection, providing a niche that other arboreal animals may be unable to exploit so soon post fire.