Feeding state and selected body temperatures in the slow-worm (Anguis fragilis)

Lizards may select higher body temperatures after feeding, but rigorous experimental evidence of this is confined to a small number of lineages. Here it was examined in an anguid lizard, namely the slow-worm Anguis fragilis, which is a semi-fossorial cool temperate species that exhibits relatively low field body temperatures. Body temperatures selected by slow-worms in a thermal gradient were low compared with many other lizards (means ranged from 25.3 to 26.4 degrees C). This indicates that low field body temperatures described previously are not due to thermoconformity in a cool environment. More significantly, selected body temperatures differed between fed and three-day fasted treatments, with an increase of 0.4-1.2 degrees C being observed after feeding. The magnitude of this increase is similar to that reported for two iguanid lizards, and shows that a postprandial response is also present in this ecologically and phylogenetically distant species.