Field response of tadpoles to conspecific and heterospecific alarm

Many organisms use chemical cues from a variety of sources to mediate preda tor avoidance. Response to heterospecific alarm cues has been demonstrated for tadpoles within but not among taxa and alarm response behavior has seld om been examined under field conditions. This study examined the response o f three sympatric amphibian larvae and predaceous larval Dytiscus sp. (divi ng beetle) to damage-release signals in natural ponds by using capture rate s from treated funnel traps as an index of larval behavior. Hyla regilla (P acific tree frog) tadpoles avoided traps treated with either crushed conspe cifics or with Rana aurora (red-legged frog) tadpoles but the larger ranids and Ambystoma macrodactylum (long-toed salamander) did not respond to eith er treatment. H. regilla tadpoles were likely susceptible to any potential predators of ranid tadpoles in these ponds and this result is consistent wi th the hypothesis that a response to heterospecific alarm occurs in sympatr ic prey with shared predators.