Diet variations across remote populations of a widely distributed snake species, the Asp viper ( Vipera aspis aspis , Linnaeus, 1758)

Documenting intra-specific diet variations among remote populations, thus across different habitats, is important to address evolutionary (e.g., phenotypic plasticity) and conservation issues (e.g., capacity to adapt to changing prey availability). We compared the diet of different populations of Asp vipers ( Vipera aspis aspis ; Linnaeus, 1758) living in contrasted habitats of France and Switzerland. We sampled 1680 individuals in five geographical areas, broadly encompassing the distribution range of the species (West to East and North to South): Group 1 = Western Central France; Group 2 = Central France; Group 3 = West France; Group 4 = South France, and Group 5 = Switzerland. We compared mean total body size (TL) of snakes and their diet. We found strong similarities among the groups with a predominance of micromammals in the diet. In mountainous area (Group 5), however, snakes included a substantial number of reptiles and fed occasionally on amphibians and birds. The diet varied ontogenetically (juveniles often consuming lizards, adults heavily feeding on mammals) and sexually (females tending to feed more extensively on mammals). Overall, our results suggest that Asp vipers maintain a diet largely based on micromammals (mostly voles), at least across their continental distribution range.