We acknowledge Jude Janith and Lahiru Rajapakhe for their help in the field.Kamal Raj Gosai helped with measuring the Crow-Billed Drongo skins.Members of the Avian Sciences and Conservation assis-ted in the fieldwork,lab work and analysis.We are grateful to Lankani Somaratne(NMSL)and Kunming Museum of Natural History,for providing details from their respective collections.Macaulay Library of the Cornell Lab of Ornithology provided the recording equipment.Uvini Senanayake helped with creating maps.We thank the editor and two reviewers for their constructive feedback on an earlier version of this manuscript.This study was funded by the Collaborative Research Grants of the University of Colombo(to SS)and the Special Talent Recruitment grant from Guangxi University(to EG).The fieldwork was conducted with the permission of WL/3/2/19/13(Department of Wildlife Conser-vation,Sri Lanka)and R&E/RES/NFSRC/2013-01-P-02(Forest Depart-ment,Sri Lanka).All authors declare that they have no conflicts of interest. （NMSL）