Ultrasonic frogs show hyperacute phonotaxis to female courtship calls


Sound communication plays a vital role in frog reproduction1,2, in which vocal advertisement is generally the domain of males. Females are typically silent, but in a few anuran species they can produce a feeble reciprocal call3 or rapping sounds4 during courtship. Males of concave-eared torrent frogs (Odorrana tormota) have demonstrated ultrasonic communication capacity5. Although females of O. tormota have an unusually well-developed vocal production system6, it is unclear whether or not they produce calls or are only passive partners in a communication system dominated by males. Here we show that before ovulation, gravid females of O. tormota emit calls that are distinct from males’ advertisement calls, having higher fundamental frequencies and harmonics and shorter call duration. In the field and in a quiet, darkened indoor arena, these female calls evoke vocalizations and extraordinarily precise positive phonotaxis (a localization error of <1°), rivalling that of vertebrates with the highest localization acuity (barn owls7,8, dolphins, elephants and humans9). The localization accuracy of O. tormota is remarkable in light of their small head size (interaural distance of <1 cm), and suggests an additional selective advantage of high-frequency hearing beyond the ability to avoid masking by low-frequency background noise5.

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Figure 1: Female’s courtship call and male’s evoked vocal responses.
Figure 2: Males' phonotactic responses to a female’s courtship call.


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This work was supported by the National Natural Sciences Foundation of China (J.-X.S.), the National Institute on Deafness and Other Communication Disorders (A.S.F. and P.M.N.), the UCLA Academic Senate and the Paul S. Veneklasen Research Foundation (P.M.N.), and the National Science Foundation (A.S.F.).

Author Contributions J.-X.S., A.S.F. and P.M.N. were responsible for project planning. All authors (except P.M.N.) conducted the behavioural experiments, J.-X.S. and Z.-M.X. analysed the behavioural data and video recordings, and J.-X.S. and A.S.F. analysed the acoustic data. All authors contributed to writing the manuscript.

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Correspondence to Jun-Xian Shen.

Supplementary information

Supplementary Audio 1

The file contains Supplementary Audio 1 with phonotactic behaviour of males of Odorrana tormota in response to female courtship calls. In response to female courtship calls (FCs), males of O. tormota produced four types of vocal responses and displayed phonotactic movement toward the loudspeaker. (WMV 1552 kb)

Supplementary Audio 2

The file contains Supplementary Audio 2 with males of Odorrana tormota show hyperacute phonotaxis to female courtship calls. Upon hearing a female courtship call, a male of O. tormota usually oriented his body toward the loudspeaker – this was followed by a long-distance hop (range: 30 - 75 cm) toward the loudspeaker. The precision of the long-distance hops was remarkable, and the male soon reached the center of the diaphragm of the loudspeaker. (WMV 1208 kb)

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Shen, J., Feng, A., Xu, Z. et al. Ultrasonic frogs show hyperacute phonotaxis to female courtship calls. Nature 453, 914–916 (2008) doi:10.1038/nature06719

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