Smooth snakes at an Iberian mountain isolate and the relationship with competing southern smooth snakes

Smooth snakes (Coronella austriaca) confined to cold-humid environments in Iberian high mountains may be threatened by the effects of climate warming, such as the expansion uphill of competing southern smooth snakes (C. girondica), but demographic studies allowing the assessment of population tendencies are lacking. Here, we determined the distributions and abundances of both species at Serra da Estrela based on records over 18 years (1993–2010). Smooth snakes comprised an isolated population at altitudes above 800 m. Abundances were highest above 1300 m, with densities of about one smooth snake per hectare above 1580 m. The distributions of the two species overlapped at altitudes of about 800–1600 m. We did not find any evidence for range shifts, or changes in smooth snake abundance over the past 18 years. Sex ratios were even, and high dietary specialization may contribute to the species' vulnerability. Efforts to conserve the smooth snake at Serra da Estrela should encompass studies aiming to improve knowledge of the species' demography, as well as continued monitoring to evaluate potential threats posed by climate warming. Our study may provide a baseline tool for future research on this poorly known snake.