We thank A.Ryzhov,S.Avdeyuk,A.Katkov,A.Bezrukov,I.Don-chenko,and A.Popov for their help with data collection in the field in Russia.We are grateful to Otani Chikara and Yann Muzika for generously providing their sound recordings of Blakiston's Fish Owl duets from Hokkaido.We would also like to thank E.E.Kozlovsky for providing us with recordings from the Russian Mainland from his fieldwork.We acknowledge financial and logistical support from the Wildlife Conser-vation Society and the Amur-Ussuri Center for Avian Biodiversity,and financial support from Columbus Zoo and Aquarium.We also acknowl-edge a Singapore Ministry of Education Tier 2 grant for financial support(WBS R154-000-C41-112).NM was supported by the Lady Yuen Peng McNeice Graduate Fellowship during the execution of this project. （WBS R154-000-C41-112）