Seasonal and ontogenic variation in the trophic spectrum of Anatolian water frogs, Pelophylax ridibundus group, in the Eastern Mediterranean (Amphibia: Anura)

Seasonal and ontogenic variation of food composition in Anatolian water frogs (Pelophylax ridibundus group) were analysed in the Seyhan and Ceyhan Deltas, southern Turkey. A total of 1,226 prey items were retrieved from the stomachs of 335 individuals (75 juveniles, 148 males, 112 females) in spring, summer and autumn. The frogs fed mainly upon invertebrates, especially insects (80.4%), and the prey spectrum was strongly influenced by prey availability in the environment. The most frequently consumed prey items were Hemiptera (31.6%), Coleoptera (29.0%), Hymenoptera (23.6%), and Diptera (21.5%). While adult frogs consume various invertebrate preys such as annelids, gastropods, arachnids, and insects, the diet of juveniles is mostly confined insects. No significant differences were found in the seasonal variation of prey types between sexes. Prey diversity and volume increased in spring and summer, and decreased in autumn with the decrease of the air temperature and reduced activity of the frogs.