Antipredator Behaviors of Newly Metamorphosed Green Frogs (Rana clamitans) and Leopard Frogs (R. pipiens) in Encounters with Eastern Garter Snakes (Thamnophis s. sirtalis)

Three experiments were conducted on antipredator behaviors of newly metamorphosed green frogs (Rana clamitans) and northern leopard frogs (R. pipiens) in the presence of a common predator, the eastern garter snake (Thamnophis s. sirtalis). Both species engaged in distinctive antipredator behaviors, i.e., crouching and ceasing to move, in the presence of active snakes. These behaviors rendered frogs less likely to be captured. Green frogs were contacted by snakes more frequently than were leopard frogs, but capture rates of individuals that had been contacted were not different between species. Green frogs allowed snakes to approach more closely, and they jumped more frequently upon initial escape, than leopard frogs. Morphological measurements showed that there were no specific differences in snout-vent length, or in snout-vent length/leg length ratios, but that the average leap distance was greater for leopard frogs compared to green frogs. The results supported the hypothesis that leopard frogs use distance from the predator in terrestrial habitats more effectively than do green frogs to avoid predation, which agreed generally with some descriptive field results reported elsewhere.