Sharing resources in a tiny Mediterranean island? Comparative diets of Chalcides ocellatus and Podarcis filfolensis in Lampione

摘要

The insular lizard microcommunity inhabiting the Lampione islet (Pelagian islands, S Italy) is constituted by a skink (Chacides ocellatus) and a lacertid lizard (Podarcis filfolensis). Their diet composition (taxa and sizes) during spring-early summerwere analysed based on 131 faecal pellets, which could be individually assigned to a lizard species and sex (only in P. filfolensis). The diet of C. ocellatus was biased towards hard prey of medium to large sizes (Coleoptera, insect larvae). Podarcis filfolensis displayed a more diverse prey spectrum including Formicidae, Coleoptera, insect larvae and minor prey not consumed by the skink, but restricted to the small items; differences between sexes were minimal. Both species were partially herbivorous.Evidence of cannibalism was found for P. filfolensis and C. ocellatus preyed upon P. filfolensis. Pseudocommunity analysis does not support community structure but instead points to convergence in trophic strategies between both species due to insular conditions. Evolutionary history, rather than resource partitioning, seems responsible for the moderate trophic overlaps recorded and even may explain why both species coexist under the harsh conditions of this tiny islet.