Estimating the population size and density of Italian wall lizards (Podarcis siculus) through photo identification capture-recapture

In the face of a global biodiversity crisis, accurate estimates of population parameters â especially size and survival â are critical for effective conservation, yet such data are often scarce due to logistical, financial, and methodological challenges. Reptiles in Europe are particularly underrepresented in population studies. Although many are protected under the EU Habitats Directive, robust estimates of population density and survival exist for fewer than half of the listed species. In this study, we present a demographic assessment of the Italian wall lizard (Podarcis siculus) using capture-mark-recapture (CMR) methods. Fieldwork was carried out in 2019 at three distinct sites in Central and Southern Italy. We employed photographic identification combined with Jolly-Seber models to estimate population size, separately for males and females. Population densities showed marked spatial variation, ranging from 102 to 384 individuals per hectare. Apparent survival and detection probabilities also varied substantially, probably reflecting differences in local environmental conditions and habitat structure. These findings reveal significant demographic heterogeneity among populations, consistent with patterns observed in other Podarcis species. Our study demonstrates the applicability and reliability of CMR approaches for reptile monitoring and underscores the need for standardized long-term population data to inform conservation management. Importantly, these represent the first density estimates for P. siculus based on CMR, helping to address a major data gap for this species of conservation concern.