Composition and scaling of male and female Alpine newt (Mesotriton alpestris) prey, with related site and seasonal effects

In amphibians, most species are female-biased sexually dimorphic and such dimorphism is often accompanied by intersexual differences in prey composition. While many aspects of foraging ecology have been studied in this group, intersexual differences have rarely been described. We examined dietary composition of male and female Alpine newts (Mesotriton alpestris) from two localities in the Czech Republic during the entire breeding period by stomach flushing. Isopoda, Cladocera, Rana eggs were the most important prey. About 16% of newts did not contain prey items. At studied localities, females were about 15% larger than males. Snout-vent length (SVL) of newts was related to the mass of consumed prey, but not its number and diversity. Analyzing the residuals from the relationships between SVL and prey characteristics, we found the effect of sex on all observed prey variables -the females consumed more prey items, more diverse prey and also in greater mass than did the males