In animals that display acoustically, males may use the presence of conspecifics to choose optimal times for display, and in doing so minimize costs of advertisement while maximizing the probability of mating success. Among anuran amphibians, it is well known that males can adjust their calling behavior in response to fluctuating social conditions. Within a species, it is not known whether males adjust their calling activity differently in response to females, and the immediate chance of mating, than in response to males, and the risk of competition for mates. In the Australian toadlet Pseudophryne bibronii, males construct terrestrial nests and call to advertise territory occupation and to attract potential mates. In this study, I presented either males or females to nesting males and found that male call type, and aspects of call structure, are influenced by the sex presented. More importantly, I found that males called at a significantly higher rate in response to females than in response to males. These results suggest that nesting male toadlets strategically adjust calling behavior according to contingent chances of male–male competition and mate attraction. These findings are unique because they indicate that males do not advertise maximally until there is an immediate chance of mating success.

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