Males of Hypsiboas goianus (Anura; Hylidae) do not assess neighbor fighting ability through acoustic interactions
In frogs, acoustic signals are the most important communication mechanism, since they may be used in several social contexts. In many anurans, the dominant frequency of calls is negatively related to body size, and in such species, this spectral parameter may be considered a good predictor of fighting ability. We experimentally investigated the vocal behavior of 30 male Hypsiboas goianus in central Brazil to answer the following questions: (1) Do males change the acoustic parameters of their calls in response to conspecific intruders? and (2) Does the acoustic behavior of H. goianus depend on the simulated body size of their opponent? We used playback of synthesized calls with high (3573 Hz) and low (3123 Hz) dominant frequency to simulate small and large males, respectively. Males reduced the rate of advertisement calling in response to playback but did not change vocal behavior in response to low-frequency and high-frequency playback. So, while males adjust their calling activity in response to simulated conspecifics, there was no evidence that they assess the fighting ability of their opponents through acoustic interactions.