Challenges of dehydration result in a behavioral shift in invasive toads

The adaptive nature of invasive species facilitates their survival in conditions that differ markedly from their native range. Behavioral changes in invasive populations are poorly explored but offer a wide potential when combined with physiological traits. For amphibians invading xeric habitats, finding water is important to function optimally and avoid dehydration. The water-finding hypothesis postulates that survival can be enhanced through the increased behavioral ability to find water. We tested the water-finding hypothesis in guttural toads (Sclerophrys gutturalis) from their native range and an invasive population. Additionally, we tested if artificially elevated corticosterone levels, which increase during dehydration, affect behavioral traits linked to water balance. In a labyrinth experiment, we observed the toads’ ability to find water in different hydration states (100%, 90%, and 80%). We found that individuals from the invasive population took longer to engage in water-searching behavior and spent more time close to the water source after finding it. Toads from the invasive population were also more active, and at 90% hydration, their attempts to find water increased. Moreover, artificially increasing corticosterone in fully hydrated invasive toads increased water-finding success. Our experiments demonstrated that invasive toads show water-conservation behaviors that can optimize water balance and might facilitate survival in an invaded xeric environment. Additionally, we suggest a link between elevated corticosterone levels and water-finding success. Our results lend support to the importance of behavior in successful invasions and the modulation of water-finding behavior by corticosterone. Invasion success is associated with behavioral and physiological adaptations of invasive species. For anuran species invading xeric habitats, the ability to find water is an important behavioral trait. Using a labyrinth experiment and toads (Sclerophrys gutturalis) dehydrated at different levels, we observed that individuals invading a hydric challenging habitat showed advantageous water-conservation behaviors (e.g., taking longer to engage in water-searching behavior and spent more time close to the water source after finding it) compared to toads from the native range. Transdermal treatment with corticosterone, a hormone that increases its plasma concentrations under dehydration, increased success of finding water in 100% hydrated animals. Our results indicate that, compared to the native population, invasive toads display water-conservation behaviors that might improve survival rates in a novel xeric environment and that experimental corticosterone elevation modulates this water-finding behavior.