Food Habits of Sympatric Larval Ambystoma tigrinum and Notophthalmus viridescens

The large overlap in diet between these species suggests that partitioning of food resources was minimal. All larvae of both species ate ostracods; ostracods were the most important prey for both, by weight and numerically. As the larval period progressed, there was an increase in the percentage of the diet, by weight, consisting of pouch snails and decrease in the percentage of the diet, by weight, consisting of ostracods and cyclopoid copepods in the diets of both A. tigrinum and N. viridescens. It may be more efficient for larger larvae to invest energy in capturing a few larger prey (snails) rather than many smaller prey (ostracods and copepods). Differences in food habits were probably due to difference in size between larvae of the two salamander species. In samples containing both species, large prey were eaten more frequently (chaoborid larvae and fingernail clams) or exclusively (corixids) by A. tigrinum whereas some small prey (cylclopoid copepods and aphids) were eaten more frequently by N. viridescens. There was no predation between species nor was there cannibalism within either species.