Variation in Intrinsic Calling Strategy With Morphology in the Túngara Frog

Abstract

When signaling to attract mates, males balance competition with energetic investment and predation risk. Modeling signaling behavior is complicated by social stimulation at the chorus, which masks intrinsic calling strategy. This study examines intrinsic calling behavior using laboratory-raised túngara frogs in the absence of social stimuli. Male frogs were placed individually in sound-attenuating call boxes, where their vocalizations were recorded continuously over periods of 24–72 hours. We analyzed how males distributed calling effort over multiple acoustic dimensions and screened for effects of body mass, snout-vent length (SVL), and age on call parameters such as duration, call rate, dominant frequency, signal amplitude, and complexity. Preliminary analyses indicate that calling occurred throughout the day but was concentrated approximately 2 hours after sunset. Despite large changes in call abundance over the night, mean call properties varied only modestly, with frequency showing the least variation. Correlation analyses further indicate that hourly call production was negatively associated with period and positively associated with duration, while amplitude was positively correlated with duration and period was negatively correlated with both amplitude and duration. These results provide the basis for a model of male calling that will facilitate tests of hypotheses about signaling strategies and improve our understanding of mating behavior in vertebrates