Should I stay or should I go? Frog breeding responses to drought events and alien predators

Abstract

Abstract Climate change is a major driver of biodiversity loss worldwide, increasingly acting through extreme climatic events such as droughts. Beyond their direct impacts on habitat availability, droughts can also generate indirect effects by altering ecological interactions, such as predator–prey dynamics. Despite growing interest, most studies focus on single species and/or are based on short-term datasets, making it difficult to discriminate between ongoing ecological processes and interannual variability. We investigated the direct and indirect effects of drought on reproductive responses in two ecologically distinct frog species ( Rana dalmatina and Rana latastei ), focusing on the choice to skip reproduction or relocate breeding activity. Using nine years of monitoring data, we examined how drought-driven breeding site loss interacts with landscapes dominated by invasive alien predators. Our findings reveal starkly different strategic responses between the two species. Rana dalmatina was more strongly affected by the direct effects of drought, as the loss of temporary breeding sites reduced reproductive activity, forcing individuals to adopt a breeding skipping strategy. In contrast, Rana latastei relied mainly on permanent waterbodies and was less sensitive to site desiccation, exploiting stable habitats even though this choice resulted in persistent exposure to invasive predators. Furthermore, R. dalmatina , females actively avoided fish-invaded sites, whereas in R. latastei the positive association with the invasive crayfish Procambarus clarkii likely reflected shared preferences for permanent waterbodies. These findings show that droughts affect amphibian reproduction through interacting direct and indirect mechanisms, with species-specific ecological traits determining whether species undergo habitat loss or severe predator exposure.