Severe, large-scale bushfire threatens metapopulation function of quokka (Setonix brachyurus) in south-western Australia

Abstract

Background: The risk of large, severe bushfires is increasing in Australia, and little is known about their impact on threatened species. Aims: This study aimed to investigated the abundance, occupancy and metapopulation structure of the quokka (Setonix brachyurus) for 5 years following a large, severe bushfire in Western Australia. Methods: Data collected across spatiotemporally replicated transects were used to estimate probabilities of occupancy and abundance, and to evaluate the influence of covariates. Key results: Quokka abundance was reduced to 16% of pre-fire levels, with distances up to 74 km separating subpopulations. Recolonising quokkas occupied habitat in parts of the landscape that had retained some vertical vegetation structure and contained a sedge-dominated understorey, and where damage by feral pigs was low. This coincided with topographic refugia that consisted of deep, mesic riparian systems or perched wetland systems. After 5 years, abundance had increased to 46% of pre-fire levels, with distances of 5-30 km separating subpopulations. Conclusion: Quokka recovery rate is slower than expected, and the metapopulation remains vulnerable to further fragmentation arising from disturbances that affect habitat patch suitability and movement corridors. Implications: Proactive protection of refugia and spatiotemporal habitat connectivity within and surrounding the fire scar is critical for metapopulation recovery.