Regional extinction vulnerability reveals hidden conservation risks for snakes in the Caatinga of Paraíba, northeastern Brazil

Due to increasing habitat loss and anthropogenic pressures in the Caatinga, biodiversity conservation remains a major challenge, particularly for poorly studied groups such as snakes. We assessed the extinction vulnerability of snake species occurring in the Caatinga of Paraíba, northeastern Brazil, using a multifactorial approach that integrates intrinsic biological traits and extrinsic human pressures. Vulnerability indices were developed based on 12 factors related to species distribution, ecology and life-history attributes. Vulnerability patterns were assessed using Principal Coordinates Analysis (PCoA) and cluster analysis. We evaluated 48 species, which showed a wide range of vulnerability values (0.19–0.67). Approximately 46% were classified as threatened (Vulnerable, Endangered or Critically Endangered), while the remaining species were categorized as Least Concern or Near Threatened. Bothrops jabrensis had the highest vulnerability, whereas Oxyrhopus trigeminus had the lowest risk. Distribution-related factors, particularly restricted range and rarity, contributed strongly to vulnerability, whereas life-history traits were important in structuring multivariate differences among species. Cluster analysis identified ten distinct groups, highlighting that endemic, rare, and species with low-tolerance to environmental disturbance are the most vulnerable. Notably, several species considered of low concern at broader scales showed higher vulnerability at the regional level. This study provides the first regional assessment of snake extinction vulnerability in the Caatinga and introduces an integrative framework that can be applied to other taxa and regions. By revealing hidden patterns of risk and emphasizing local-scale analyses, our findings provide insights for conservation planning and biodiversity management under increasing environmental change