| Ontogenetic diet change is well known in anurans. During 2012~2013, the diet composition and ontogenetic diet shifts were examined in piebald odorous frogs (Odorrana schmackeri) in the Thousand Island Lake. Frogs were captured by hands, body indices (Snout-vent length, weight and head width) were measured and gut contents were flushed by stomach flushing. All prey items were identified to lowest possible taxonomic level (usually Family). Schoener’s overlap index was used to evaluate the diet composition overlap between sexes and different years. We used Spearman correlation analysis to test whether total prey volume, single prey volume, prey number and the frequency of six major prey items were dependent on Snout-vent length (SVL). At last, a total of 838 frogs were captured and 2 178 prey items were documented. This frog had a great diversity of feeding habits and their prey items belonged to 78 families (Table 1). However, the diet breadth of this frog was narrow. As the frog sizes increased, the total volume (R=0.522, P<0.001, Fig.1a) and single volume (R=0.416, P<0.001, Fig.1b) of prey items increased, but the number of prey (R=﹣0.098, P=0.011, Fig.1c) decreased. The frequency of small prey items, such as Hemiptera (R=﹣0.649, P=0.001, Fig.2a), Hymenoptera (R=﹣0.593, P=0.002, Fig.2b) and Isoptera (R =﹣0.54, P =0.006, Fig.2c), became lower with increasing frog body sizes. In contrast, the frequency of large prey items, including Orthoptera (R =0.675, P <0.001, Fig.2d) and Lepidopterous larvae (R =0.489, P =0.015, Fig.2e) consumed by larger frogs was higher. Our results indicate that ontogenetic diet change occurs in Odorrana schmackeri and ontogenetic change should be included in further diet studies. |
