The importance of naturalized quarries as amphibian breeding sites: a case study in central Spain

Naturalized quarries can host rich amphibian communities, potentially playing an important role in local and regional population dynamics. Despite their importance for conservation, few studies have evaluated their potential to host large, viable populations and to connect breeding nuclei in neighboring areas, promoting long-term demographic resilience at the regional scale. We used photo-identification as a capture-mark-recapture method to estimate the population sizes and dispersal patterns of two amphibians of regional conservation concern (Pleurodeles waltl and Pelodytes punctatus), which breed in temporary ponds in an abandoned, naturalized quarry in SE Madrid (central Spain). We also surveyed all water bodies potentially harboring amphibian populations in an 80 km2 area centered in our study site to detect additional breeding nuclei of the two species. Both species are abundant in the core study site, with estimated population sizes of around 300 individuals in P. waltl and about 800 in P. punctatus. We recorded 23 accumulated displacements, ranging from 80 to 840 m, performed by 20 individuals of P. waltl captured on multiple occasions, but were unable to detect spatial displacements of P. punctatus during the study. Regional surveys confirmed the presence of P. waltl and/or P. punctatus in 7 additional locations, mostly quarries, at distances of 0.6-4.4 km from the study site. Our results show that temporary ponds in naturalized quarries can represent key assets for the long-term resilience of amphibian populations in areas where human action has resulted in extensive habitat fragmentation and loss.