Moving in the Dark: Enlightening the Spatial Population Ecology of European Cave Salamanders

Space use and movement are fundamental aspects of organisms' ecology, mirroring individual fitness, behavior, and life-history strategies. These mechanisms are shaped by environmental heterogeneity, which often makes it difficult to understand these dynamics. Subterranean habitats are simplified and understudied environments, potentially ideal for evaluating the fine-scale spatial ecology of organisms. Spatial capture–recapture (SCR) methods allow us to investigate animal space use and movement, including spatially explicit observation data on individuals, to assess the relationship between population dynamics and landscape ecology. In this context, we assessed individual interactions, movement ecology, and activity patterns of a subterranean population of the cave salamander Speleomantes strinatii, applying SCR modeling to a photographic capture–recapture dataset of 104 identified individuals (43 males, 35 females and 26 subadults). Analysis of overlap indices showed that the proportion of males' home range (HR) was more covered by females' HR than vice versa (U = 25, p = 0.038). During the monitoring, females traveled longer distances in less time than males (0.60 vs. 0.22 m/day). Finally, salamanders tended to be more active during summer periods, showing a preference for the inner sectors of the cave and rougher cave walls. Combining the analysis of spatially explicit capture history (overlap and movement estimates) and SCR (activity pattern, sex-specific density and space use), we enlightened new features and confirmed previous knowledge of the spatial ecology of S. strinatii. Our study demonstrates how structured capture–recapture data can be used to infer individual interactions and movement in low-complexity habitats and is open to the application of SCR methods in more complex environments for revealing finer-scale ecological variation with important conservation implications.