Ecological Energetics and Food Acquisition in Dense Menorcan Islet Populations of the Lizard Podarcis lilfordi

1. Ecological energetics and water fluxes were compared between populations of the lacertid lizard Podarcis lilfordi from the Menorcan islets of Aire and Nitge (Balearic Islands, Spain) during a non-reproductive summer period using the doubly labelled water technique. 2. Lizards from Aire were larger than those from Nitge (9.6 ± 0.58 g vs 5.1 ± 0.38 g, respectively) and consequently had higher field metabolic rates (FMR) (1.739 ± 0.151 KJ day −1 vs 1.255 ± 0.977 kJ day −1 ). 3. FMR were lower in the Aire population, when the effects of the differing body masses were removed. 4. There were substantial differences in food availabilities between the two islets and this was reflected in strong dietary differences between the lizard populations