Spring basking by Vipera aspis: Observations from Italy and France on the displacement distances of basking vipers from their hibernacula

Patterns of movement are an important component in animal ecology. In temperate zone reptiles this includes movement soon after emergence from hibernation, often a crucial period for courtship and mating. Due to the effects of climate or habitat, intra-specific differences in movement in different areas might be expected. We examined this possibility using long-term data on the displacements of aspic vipers (Vipera aspis) from their hibernation dens in Italy and France; the two sites differed in latitude, altitude and vegetation cover. We found no statistically significant differences between Italy and France in displacement distances from the dens. However, in both countries displacements were significantly greater in the afternoon in both males and females. This was thought to be due to differences in cover between the localities. The likely explanation is that the movement of the sun across the sky may leave morning basking positions in the shade and require the snakes to move further from their dens to continue basking.