The ability of the frog-eating bat to discriminate among novel and potentially poisonous frog species using acoustic cues

Abstract

The bat Trachops cirrhosus eats frogs and uses the frogs' vocalizations to locate them. It is able to discriminate between poisonous and palatable prey species on the basis of acoustic cues alone. In this study we presented bats with pairs of novel frog calls (i.e. calls with which the bats had no prior experience) which, to our ears, differed in the degree to which they were similar to the call of a local, poisonous species, Bufo typhonius. In all cases the bats were more often attracted to the call that was least similar to the call of B. typhonius. One call which was preferred when it was the member of one stimulus pair was avoided when it was the member of another pair: therefore, bats seemed to classify the calls in a continuous fashion. This has interesting implications for the potential of frog vocal mimicry complexes to evolve under the influence of bat predation. Acoustic analysis of the calls suggests that discrimination was primarily based on temporal properties of the calls.