Abstract
Several recent studies have suggested an innovative method for estimating the food sources, feeding habits, and trophic position of consumers in food webs, based on the compound-specific stable isotope analysis (CSIA) of amino acids. In this study, we used CSIA to study terrestrial mammals in a controlled feeding experiment with captive Asiatic black bears (Ursus thibetanus). The trophic position is estimated to be 1.7-1.9 for the bears, which is consistent with their actual trophic position (approximately 2). We also investigated the feeding habits of six wild Asiatic black bears (the same species as the captive bears; three were test animals suspected of feeding on trout and the others were controls) in the area around a rainbow trout farm. The flux of trout-derived proteins in the bear diet was calculated from the observed isotopic composition of amino acids. The results show that of the three test animals, two clearly fed on rainbow trout from the farm but other did not. Although this study is the first simple and systematic investigation of the ecological application of CSIA of amino acids to modern terrestrial mammals, we conclude that this technique is potentially useful in estimating the trophic position, food sources, and feeding habits of wildlife in ecological and biological studies.
