Influence of conspecific and heterospecific cues on phonotaxis behavior in a polyandrous treefrog

Abstract

Abstract: Although a large proportion of the literature has addressed the direction and preference of female choice in frogs, research about how males locate a breeding site and what strategies are involved in aggregation has been much less explored. By using broadcasting tests on a polyandrous choral treefrog Rhacophorus prasinatus, we examined how male frogs use conspecific and heterospecific signals to locate a chorus by asking the following questions: (1) Do male frogs prefer to join a large or a small chorus? (2) Do male frogs prefer to approach a high-quality or a low-quality male? (3) Do males utilize heterospecific calls to locate the potential breeding sites? (4) Do male frogs orient toward or avoid choruses containing heterospecific calls? Our results indicated that males prefer to join a large rather than small chorus. Low-quality males tend to approach high-quality males, which might be explained as the sneaking behavior of satellite males. Furthermore, males may use heterospecific calls delivered by a noncompetitive sympatric species (a ranid frog) to find potential breeding sites, but not by a sympatric competitor (another rhacophorid frog) that occupies a similar niche. Although the males did not show significant preference between conspecific chorus and mixed-specific chorus in the broadcasting tests, recapture records in the wild indicated that a high ratio of males would leave the mixed-specific choruses and move toward conspecific choruses in the next capture event. Significance statement: Although a large proportion of the literature has addressed the direction and preference of female choice in frogs, research about how males locate a breeding site and what strategies are involved in aggregation has been much less explored. Our study represents one of the first to test the orientation of males during breeding season, when the spatial scale in the experimental design is comparable to the real situation in the wild. Our results supported the prediction that both conspecific and heterospecific cues are used as information for males to assess the quality of breeding sites. Heterospecific calls may play dual functions for the males, which might become interference when coexisting with conspecific calls but may also provide cues for a potential habitat when conspecific calls are absent.