Protected area coverage has a positive effect on koala occurrence in Eastern Australia

Abstract

Protected areas (PAs) are crucial conservation tools implemented worldwide to conserve biodiversity. Although PAs can positively impact wildlife populations, their ecological outcomes vary substantially depending on PA management and governance. Recent calls have highlighted the need to better assess the role of area-based conservation in preventing biodiversity loss. This is crucial to improve PA effectiveness in order to meet global biodiversity goals. Here we take advantage of a unique dataset composed of 2230 surveys conducted with koala detection dogs across Eastern Australia, to assess how protection status affected the occurrence of a threatened specialist folivore. We assessed if coverage of protected forest influenced koala presence or absence at two spatial scales (1 and 3 km), for (i) strictly and (ii) all protected areas. We also investigated if PA effects were explained by differences in habitat composition (percentage of secondary forest) between protected and unprotected areas. Taking confounding factors into account, we showed that forest protection (all IUCN categories) had a significant positive effect on koala occurrence, which increased by ~ 10% along the forest protection gradient. Contrarily, koala occurrence was not affected by strictly protected areas. In addition, adding the percentage of secondary forests in our models did not modify the statistical effect of PAs on koala occurrence, suggesting that forest composition is not the driver of the observed difference along the protection gradient. Our results contribute to a broader understanding of the effects of PAs on a threatened marsupial and call for further attention to assessments of PA effectiveness in Eastern Australia, a global biodiversity hotspot.