Caves as breeding sites for salamandra salamandra : differences with subterranean artificial springs, pre-metamorphic larval stages and conservation issues

Several studies documented the presence of amphibians in caves, yet investigations on the factorsdetermining amphibian distribution and reproduction in underground environments remain scarce. In this study we analyze the environmental features allowing the reproduction of the fire salamander Salamandra salamandra in natural caves, and we compare the features of natural and artificial hypogeous springs. We performed surveys to assess salamander distribution and measured environmental variables in 61 natural caves. We recorded larval occurrence in 18% of caves, in waterbodies distant up to 50 m from the entrance. Larvae were associated to the most accessible caves, with gentle slope below the entrance, with waterbodies nearby the entrance and hosting rich macrobenthos communities. Occupied natural and artificial caves had similar environmental features. Larvae metamorphosing in caves attained larger body size than those grown under outdoor conditions. This result shows the key importance of the cave accessibility also for natural caves and confirms the S. salamandra ability to breed in underground damp biotopes if placed in a suitable environmental context. However, frequent water catchments for human use prevent the access of animals and threaten these populations.