Brunei Darussalam, Cambodia, China (mainland), Hong Kong (China), Indonesia, Japan, Laos, Malaysia, North Korea, Philippines, Russia (Asian), Russia (Central Asian) (B), Singapore, South Korea, Taiwan (China), Thailand, USA, Vietnam.
Breeds south-central and south-eastern Siberia, northern Mongolia, north-eastern China (Inner Mongolia and Manchuria), northern Korea, Russian Far East and Sakhalin I. Non-breeding south-eastern China (Guangxi, Guangdong, Hainan), south-eastern Asia, Greater Sundas, Philippines and Sulawesi.
Population
Estimated population is unknown (2010).
BirdLife International Species Factsheet