JUVENILE TOADS AVOID CHEMICAL CUES FROM SNAKE PREDATORS

Chemical senses mediate several anuran behaviours, including predator avoidance by larval frogs. Predation by garter snakes is an important influence on the survival of post-metamorphic, juvenile toads (Bufo sp .). Studies have shown that visual, rather than chemical, cues are imp ortant for predator avoidance in post-metamorphic juvenile bufonids. T his study investigated the ability of post-metamorphic, juvenile great plains toads, B. cognatus, and southwestern toads, B. microscaphus, t o detect and avoid chemical cues from their respective predators, the eastern plains garter snake, Thamnophis radix, and the wandering garte r snake, T. elegans. Juvenile B. cognatus collected in South Dakota we re observed on unmarked paper towels significantly more than on simila r towels treated with chemical cues from T. radix. Similarly, juvenile B. microscaphus from Arizona were observed on unmarked towels signifi cantly more than on towels marked with chemical cues from T. elegans. Toad avoidance of snake odour was apparently not a generalized respons e to reptile chemical cues: juvenile B. microscaphus continued to avoi d snake odours when these were simultaneously presented with odours fr om sympatric lizards, Sceloporus undulatus. Hence, juvenile B. cognatu s and B. microscaphus apparently detect and avoid chemical cues from s nake species that prey on them. (C) 1997 The Association for the Study of Animal Behaviour.