Growth, longevity and age at maturity in the European whip snakes, Hierophis viridiflavus and H. carbonarius

Abstract

Age and size at maturity are major life history traits, because they influence lifetime fecundity. They represent the outcome from complex interactions among environmental pressures (abiotic and biotic) and individual characteristics. They are also difficult to measure in natural populations and thus they are rarely appraised, especially in reptiles due to the elusive nature of juveniles. Using skeletochronology to circumvent these difficulties, this study aims to compare age structures, longevity, age-size relationships, growth curves, age and size at maturation and potential reproductive lifespan in three populations of the European whip snake (two Hierophis viridiflavus, one H. carbonarius). We measured the body size and counted the skeletal growth marks on 132 specimens, accidentally killed or from museum collections (72 from NW France [Chizé]; 28 from Tuscan Archipelago [Montecristo], Italy; 32 from S Italy [Calimera]). General patterns of age at maturity and longevity were consistent with previous studies based on recapture investigations. Strong differences among populations suggest local adaptation to contrasted environmental conditions. These results suggest that skeletochronology is a useful technique that can be applied opportunistically in snakes (e.g. using road-kills) in order to collect otherwise unavailable data that are essential to address fundamental questions regarding longevity, life-history traits and to perform population viability analyses.