Are fibrocement slabs a useful tool for monitoring reptiles? The case of Hierophis viridiflavus in its south-western limit of distribution

The established methodology in detection and long-term reptile monitoring programmes has so far focused on visual encounter surveys (VES), a method that can yield very high capture rates for snakes, but, even when carried out in favourable habitats, can also be very limited. Therefore, one passive sampling method was tested: fibrocement slabs. A total of 81 slabs were placed in nine sampling stations in the southern part of Irún (Basque Autonomous Community, Spain). During the two years of sampling (2020–2021) a total of 79 reptile records were obtained, of which 33 were records of the European whip snake corresponding to 28 individuals. There was at least one reptile record in each transect and 75% of the reptile species present in the study area were detected. However, we did not identify any trend over time that indicated an increase in the number of individuals captured during the second year. All in, the data obtained have provided positive results; therefore, it could prove to be a very useful methodology for reptile studies, in particular for ophidians.