1. Chengdu Institute of Biology， the Chinese Academy of Sciences, Chengdu 610041, China 2. The Northwest Sichuan Eucational Research Center of Giant Panda Protection, Mianyang Normal University, Mianyang 621000, China 3. College of Life Science, China West Normal University, Nanchong 637002, China
We examined the competitive ability of larval toads (Bufo gargarizans) and frogs (Rana kukunoris) which co-occur in natural pools in the Jiuzhaigou Nature Reserve. We measured the activity level, growth rate, mass at metamorphosis and larval period in a laboratory experiment. Tadpoles of B. gargarizans were significantly more active when food was abundant than scarce, while there was no significant difference in the activity of R. kukunoris tadpoles at different food levels. At low food availability, mass at metamorphosis and growth rate of R. kukunoris were significantly increased in the presence of B. gargarizans, whereas the presence of R. kukunoris had no significant effect on the mass and growth rate of B. gargarizans. In all treatments, the larval period of B. gargarizans at low food availability was the shortest. These results suggest that B. gargarizans can adapt to different food levels by changing their activity rate. At high food level, B. gargarizans increased activity to gain more food. At low food level, B. gargarizans decreased activity and achieved early metamorphosis. However, when food resources were limited, R. kukunoris could gain more food than B. gargarizans.