Time series analysis of sound data on interactive calling behavior of Japanese tree frogs

Abstract

We have analyzed time series data of sound on interactive calling behavior of two male Japanese tree frogs (Hyla japonica; Nihon-Ama-Gaeru). First, we have extracted two time series data mainly corresponding to respective frogs from the single time series data of calls of two frogs by the free and cross-platform sound editor Audacity. Then, we have quantitatively analyzed timing and inter-call intervals of respective frogs. Finally, we have characterized nonstationarily temporal change of the interactive calling behavior of two frogs by analysis of the cross recurrence plot. The results have shown that a pair of male frogs called in almost anti-phase synchronization after a short-term period of nearly in-phase synchronization, which implies existence of complex interactive calling behavior of two male frogs.