Differential effects of sound level and temporal structure of calls on phonotaxis by female gray treefrogs, Hyla versicolor
We investigated how communication distance influenced the efficacy of communication by studying the effects of two attributes of male chorus sounds, namely, reduction in sound level and degradation of temporal sound structure, on attraction and accuracy of female phonotaxis in gray treefrogs, Hyla versicolor. For this, we conducted acoustic playback experiments, using synthetic calls and natural calls recorded at increasing distances from a focal male as stimuli. We found that the degradation of temporal structure had a greater effect on signal attractiveness than did the reduction in sound level, and that increasing sound level preferentially affected the attractiveness of proximally recorded calls, with less temporal degradation. Unlike signal attraction, accuracy of female localization increased systematically with the sound level. These results suggest that the degradation of temporal fine structure from both the chorus and signal-environmental effects imposes a limit for effective communication distances for female treefrogs in nature.
KeywordsAnuran Acoustic communication Sound localization Orientation Auditory signal processing
We thank the University of Missouri-Columbia and the Missouri Dept. of Conservation for site access and capture permits. Carl Gerhardt provided advice and material support, and Oliver Beckers, Sarah Bush, Noah Gordon and Sarah Humfeld provided valuable advice and comments. Paul Kimball, Stephanie Kleyman, and Leah Reynolds aided in animal collection and running experiments. Atulya Iyengar provided valuable spectral analysis advice, and Daniel Eberl and Bernd Fritsch provided indispensable advice, comments, and feedback on the manuscript. Research funding was provided by a National Science Foundation Collaborative Research in Computational Neuroscience (CRCNS-0422073) Grant to ASF and a National Science Foundation Grant (IOB-0445286) to JS. All experimental procedures were approved by the Institutional Animal Care and Use Committee of the University of Illinois.
Compliance with ethical standards
Conflict of interest
The authors declare no conflict of interest.
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