Impalatability of tadpoles of Hyla semilineata (Anura: Hylidae) to snakes of the genus Liophis (Colubridae: Xenodontinae

Abstract

In captivity, Liophis viridis and Liophis miliaris were fed on tadpoles of Scinax pachychrus, Hyla semilineata and Rana catesbeiana. The tadpoles of S. pachychrus and R. catesbeiana were consumed. In the first attempt of feeding them with tadpoles of H. semilineata, the snakes regurgitated the tadpole and there was no more acceptance of H. semilineata tadpoles in other attempts. In order to test possible learning of the impalatability of the H. semilineata tadpoles for the snakes, it had been offered tadpoles of H. semilineata together with tadpoles of S. pachychrus. The test was repeated other three times, by associating tadpoles of H. semilineata and R. catesbeiana. Individuals of H. semilineata were always rejected, but the tadpoles of the other species were consumed. Aparently, tadpoles of H. semilineata may liberate irritating substances for the gastric mucosa of its predators, and the snakes could learn and distiguish between the palatable and unpalatable tadpoles.