Contrasting population declines and drivers of ecological refuge for two range-restricted amphibians

For species in decline or under threat, identifying and defining refuge areas that promote their persistence can inform management actions such as translocations. Here, we aimed to identify areas of ecological refuge for Anstisia alba and Anstisia vitellina, two threatened and range-restricted frog species subject to climatic and environmental stress. We quantified the extent of range decline over the last four decades, investigated the landscape-scale factors most associated with persistence of frog populations, and developed a method to identify areas with hydrological resilience. Long-term monitoring showed that the extent of occurrence of A. alba has declined by over 50% since the 1980s and has contracted from all edges of their former range. Conversely, only one A. vitellina population has become locally extinct, and the species’ extent of occurrence has expanded due to conservation introductions. Intact native vegetation cover and lower fire frequency surrounding A. alba sites were the best landscape-scale predictors of population persistence. We also determined that streams within A. vitellina habitats, as well as those in the eastern area within A. alba’s range, receive substantial groundwater inputs during spring and may be more resilient to hydrological change than areas with less groundwater connectivity. The important ‘wet-spots’ identified for A. alba and A. vitellina are also likely to be refuges for other species, providing conditions that support survival during drier and hotter conditions.