Transmission Effects on Temporal Structure in the Advertisement Calls of Two Toads, Bufo woodhousii and Bufo valliceps


Department of Zoology, University of Texas, Austin, Texas 78712, USA; Dr. B. K. Sullivan, Department of Zoology, University of Maine, Orono, Maine 04469, USA


We measured degradation of temporal structure in the advertisement calls of two species of toads (Bufo woodhousii and B. valliceps) as a function of transmission distance. Degradation, measured as the ratio of the amplitudes of pulse and interpulse interval, increased with distance and was significantly greater in B. valliceps than in B. woodhousii. These results are compared to previous reports of neural thresholds for units in the torus semicircularis that are responsive to the interaction of depth and rate of amplitude modulation in B. woodhousii and B. americanus. We suggest that the degradation of temporal structure that we measured has behavioral and neurophysiological consequences for communication.