Acoustic radiation patterns of mating calls of the túngara frog (Physalaemus pustuosus): Implications for multiple receivers

In order for a signal to be transmitted from a sender to a receiver, the receiver must be within theactive space of the signal. If patterns of sound radiation are not omnidirectional, the position as wellas the distance of the receiver relative to the sender is critical. In previous measurements of thehorizontal directivity of mating calls of frogs, the signals were analyzed using peak orroot-mean-square analysis and resulted in broadband directivities that ranged from negligible to amaximum of approximately 5 dB. Idealized laboratory measurements of the patterns of acousticradiation of the mating calls of male túngara frogs Physalaemus pustulosus, along axes relevant tothree receivers in this communication network, female frogs in the horizontal plane, and frog-eatingbats and blood-sucking flies above the ground, are reported. The highest sound pressure level wasradiated directly above the frog, with a 6 dB reduction radiated along the horizontal direction.Band-limited directivities were significantly greater than broadband directivities, with a maximumdirectivity of 20 dB in the vertical plane for harmonics near 6 kHz. The implications with regard tomating and predator-prey interactions are discussed.