ACKNOWLEDGEMENTS
We thank Tamás Székely for his advice regarding data collection and manuscript writing. We thank Mallory Eckstut (www.liwenbianji.cn/) for linguistics comments. Thanks to Li Xu, Zihao Song, Xiao Huang and Xin Lin for their assistance at fieldwork. This research was funding by the China Postdoctoral Science Foundation (No. 2019M663221) and the British Ornithologists’ Union’s Career Development Bursary to ZS; the Open Fund of Key Laboratory of Biodiversity Science and Ecological Engineering, Ministry of Education to YL.