Advertisement calls were recorded in the field at the air temperature of 18–20 °C using a SONY PCM D100 digital sound recorder. The sound files in wave format were sampled at 44.1 kHz with 24 bits in depth. Praat 6.0.27 (Boersma 2001 ) was used to obtain the oscillogram, sonogram, and power spectrum (window length = 0.005 s). Raven pro 1.5 (Cornell Lab of Ornithology, 2003-2014) was used to quantify the acoustic properties (window size = 1024 points, fast Fourier transform, Hamming window with no overlap). The following measurements were taken for each call: call duration (the time between onset of the first note and offset of the last note in a call), note duration (the time between onset and offset of a note), note rise time (the time between onset and max amplitude of a note), and note interval (the time between adjacent notes in a call). Comparison bioacoustics descriptions of known congeners were obtained from the literature (Matsui and Utsunomiya 1983 (link); Chou 1999 ; Fei et al. 2007 , 2009 ; Chuaynkern et al. 2010 ; Lyu et al. 2017 (link), 2019 (link); Li et al. 2019 (link)).
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