Accuracy of phonotaxis by the green treefrog (Hyla cinerea)

Summary1.Phonotactic approaches (N=156) of 42 female green treefrogs (Hyla cinerea) were videotaped over a distance of 3.75 m in response to synthetic mating calls (0.9 kHz and 0.9, 2.7 and 3.0 kHz).2.To quantify the accuracy of phonotaxis, jump anglesγ and head orientation angles α were measured (Fig. 2) when the animals were 1 m or farther from the sound source.3.Phonotaxis was extremely accurate in response to the 3-component call, which is behaviorally equivalent to the male's natural mating call. The mean jump angle was $$\bar \gamma = 16.1^\circ$$ (Fig. 5). Head scanning occurred prior to about 25% of the jumps. The accuracy of head orientation after scanning was even greater $$(\bar \alpha = 8.4^\circ )$$ as were the subsequent jumps $$(\bar \gamma = 11.8^\circ )$$ (Fig. 6 and Table 1).4.With respect to the two synthetic calls no statistically significant differences in jump accuracy were found (Table 1). Thus the high frequency components around 3 kHz, normally found in the mating call, do not enhance the accuracy of sound localization.5.Our results are discussed in terms of models of sound localization in vertebrates and invertebrates, and we suggest that the treefrog's ear must act as a sound pressure gradient receiver.