Diet of Chinese skink, Eumeces chinensis: is prey size important?

The diet of the skink, Eumeces chinensis (Lacertilia: Scincidae), in Xiamen (Amoy), China was examined using stomach analysis during April and May, and its selection of prey size was tested by feeding trials. Insects (primarily Coleoptera, Lepidoptera, and Orthoptera), gastropods and arachnids constituted most of the E. chinensis diet, but earthworms, leeches, crustaceans and fish were also consumed. In the field, male skinks ate more prey items that were 11-20 mm in length than other size classes. When presented with a choice of different-sized prey in the laboratory, male E. chinensis exhibited a strong preference for prey items 11-20 mm in length over other size classes. The relationship between prey size and handling time was exponential, indicating that there is an upper limit to the ability of E. chinensis to process prey. Mean energy intake for handling different-sized prey showed that selection of midsizeclass prey items would provide male E. chinensis with the most energy-efficient prey option. These results indicate that prey size selection in E. chinensis favors maximization of rates of energy intake, which is in agreement with optimal foraging theory.