Abstract:

Aims: Sound communication plays a crucial role in the reproductive process of concave-eared torrent frogs (Odorrana tormota). The vocalization strategies adopted by the male O. tormota under sexual selection pressures have particular research significance. For example, it can help us to better comprehend the effect of sexual selective pressure on amphibian calls. However, there is still a lack of research on the adaptation strategies of male O. tormota under different chorus periods.

Methods: Based on the field experiments, we labeled male O. tormota (n = 12) from March 2021 to May 2021. We used Wilcoxon signed-rank test to examine the difference between the total content of nonlinear vocal phenomena (NLP) and its components (chaos content, subharmonics content, frequency jump), and both the duration of the call and calling rate of male O. tormota (n = 12) during the high and low tide of the chorus.

Results: There were no significant differences in some NLP components (such as chaos content and subharmonics content) and the duration of the call of male frogs between the high and low tide of the chorus. However, the total content of NLP and some NLP components (such as frequency jump) in the low tide period of the chorus were significantly higher than those in the high tide period of the chorus. Similarly, the calling rate during the chorus in high tide was significantly higher than those in the low tide.

Conclusion: The calling strategies of male O. tormota in different chorus periods are not alike. During the low tide period, when there is less sexual selection pressure, male O. tormota are better able to attract females by increasing the NLP content in their calls, expanding the distance of sound transmission, and increasing the unpredictability of sound. During the high tide period, when there is more sexual selection pressure, male frogs make individual calls more prominent by increasing the calling rate, thereby improving the success rate of amplexus.

Key words: Odorrana tormota, chorus periods, vocal characteristics, nonlinear, sexual selection