Feeding habits of the sand lizard, Lacerta agilis, from North-Western Italian Alps

Abstract

The dietary habits of a population of the sand lizard Lacerta agilis were studied in the Alpine valley Stura di Demonte, Northwestern Italy. The faecal contents of 33 adults (16 females and 17 males) and 8 juveniles were analysed. There were negligible sexual differences in terms of trophic diversity and of the overall diet based on taxonomic prey categories. Juveniles had a lower prey diversity value in comparison with females but not with males. There was a positive relationship between the total number of prey items found in individual faecal contents and lizard body size, and this result may explain the more diverse diet of adults in comparison to juveniles. When the adult trophic strategy was analysed by means of the relativized electivity index, that takes into account prey availability, it was observed that the main taxonomic prey groups were eaten according to their proportion in the environment, with the only exception of ants (Formicidae) that were highly avoided by lizards.