Diet Composition And Its Influencing Factors Of The Piebald Odorous Frog Odorrand Schmackeri In Fragmented Habitats In The Thousand Island Lake

Both habitat fragmentation and ontogenetic change may affect the diet of species in amphibians. During2012-2013, diet composition, effects of habitat fragmentation on diet and ontogenetic diet shifts were examined in the piebald odorous frog {Odorrana schmackeri) in the Thousand Island Lake. Frogs were captured by bare hands, body indices were measured including Weight, Snout-Vent Length (SVL) and Head Width, and gut contents were flushed by stomach flushing. All prey items were identified to lowest possible taxonomic level (usually Family), and the length and width of prey were measured for further analysis. At last, a total of838frogs were captured and2179prey items were documented. The results showed that:(1) This frog had a great diversity of feeding habits and its prey items belonged to78families. However, the diet breadth was narrow, and there was a high overlap between male and female diet. Male consumed more prey items of Coleoptera and Hemiptera, while female fed on more Orthoptera and Lepidopterous larvae. The effects of habitat fragmentation on the diet of piebald odorous frog were weak. Between mainland sites and islands, there was no significant difference for Coleoptera and Hemiptera consumed by frogs. However, frogs inhabited in islands fed on more prey items of Hymenoptera and Isoptera. There were no significant patterns of six major prey items consumed by frogs to vary with island area or isolation distance.(2) Sexual size dimorphism (SSD) and individual diet variation occur in Odorrana schmackeri. Both phenotypic (SSD) and diet variation of this frog were used to test the niche variation hypothesis, but our results cannot be taken as evidence in favor of this theory.(3) As the frog sizes increased, the total volume and single volume of prey items increased, but the number of prey items decreased. The frequency of small prey items (Hemiptera, Hymenoptera, Isoptera) became lower with increasing frog body sizes. In contrast, the frequency of large prey items (Orthoptera, Lepidopterous larvae) consumed by larger frogs was higher.In conclusion, our results indicate that ontogenetic diet shifts and individual diet variation occur in Odorrana schmackeri. Habitat fragmentation may affect the prey electivity of this frog, but the effect is limited. Both ontogenetic change and habitat factors should be considered in further amphibian diet studies.