Age and growth of the sand lizards (<i>Lacerta agilis</i>) from a high Alpine population of north-western Italy

Abstract

We studied growth and longevity of Lacerta agilis from a sample (34 adults and 2 small-sized juveniles) of a population living at high altitude in north-western Italy using skeletochronological method. Snout vent length (SVL) mean of males did not significantly differ from that of females although the latter were in average bigger (SVL ± SD, males: 69.3 ± 7.1 mm, n = 11; females: 73.9 ± 9.7 mm, n = 22; Mann-Whitney U-test, U = 1.76, P = 0.077). Age ranged from 2 to 4 years (mean age ± SD = 2.3 ± 0.2) in males and from 2 to 3 years in females (mean age ± SD = 2.59 ± 0.5 years). Age mean did not significantly differ between the sexes (Mann-Whitney U-test, U = 1.35, P = 0.174). The two juveniles were 30 and 32 mm in SVL and both were 1-2 months old. In both sexes, a significant positive correlation between SVL and age was recorded although weakly significant for males (Spearman’s correlation coefficient, males: rs = 0.70, P = 0.05; females: rs = 0.75, P < 0.001). Von Bertalanffy growth curves well fitted to the relationships between age and SVL and showed a different profile between males (asymptotics size, SVLmax = 81.9 mm; growth coefficient, k = 0.63) and females (SVLmax = 100 mm; k = 0.40). Results indicate that individuals of L. agilis studied by us are short-living when compared with other populations of the same species.