Demography and terrestrial seasonal dynamics of a threatened fossorial toad (Pelobates cultripes) across climatic and landscape gradients: Implications for conservation

Long-term demographic data for fossorial amphibians remain scarce, yet are critical for understanding population trajectories and guiding conservation actions. In this study, capture–mark–recapture monitoring of the Western spadefoot toad ( Pelobates cultripes ) was conducted in France across contrasting contexts: an Atlantic coastal forest site with a permanent pond (Le Porge) and two Mediterranean agricultural sites with mainly man-made ponds of variable hydroperiod (Le Plan and Les Tours). Using Pradel robust-design models, we estimated seasonal capture probability, seasonal population size, adult apparent survival, and recruitment. Capture probabilities were low to moderate (0.07–0.22) and varied mainly among seasons, with the highest mean detectability at Le Plan. Estimated seasonal population sizes were broadly comparable between Le Porge and Le Plan (typically 200–350 active adults per season), whereas Les Tours supported markedly smaller numbers (50–100), and abundance was generally higher in spring than in autumn. Apparent survival varied with season and sex, and was higher over the autumn–spring interval than over the spring–autumn interval. Mean estimates suggested lower survival at Le Plan (0.63) than at Le Porge (0.76) and Les Tours (0.83), whereas recruitment showed the opposite pattern, with higher mean estimates at Le Plan (0.40) than at Le Porge and Les Tours (0.11–0.12). These patterns should be interpreted cautiously given the influence of sex, season, and time-dependent effects, as well as the confounding effect of site and study period, but may reflect differences in demographic turnover among populations. These results provide the first site-level demographic estimates for P. cultripes in France and may help inform targeted management actions, including mitigation of road mortality, creation of ponds with diverse hydroperiods in agricultural landscapes, and improved connectivity for small isolated populations.