China (mainland), Hong Kong (China), India, Laos, North Korea (B), Philippines, Russia (Asian), South Korea (B), Thailand, Vietnam.
Breeds central and eastern China (southern Gansu and Sichuan east to Jiangsu and western Zhejiang). Non-breeding southern and south-eastern China, Taiwan, north-western Thailand, northern and central Indochina and northern Philippines.
Population
Estimated population is unknown (2010).
Manchurian Bush Warbler (Horornis canturians) [XC81409]
by Frank Lambert from Just over the border in North Korea from the Chinese city of Dandong, China (?)
Manchurian Bush Warbler (Horornis canturians) [XC406633]
by Kuan-Chieh (Chuck) Hung, Taiwanbirdguide.com from Qingchuigo Creek Reiver Fish Reserve, Lugu Township, Nantou County, Taiwan Province, Taiwan (song)
Subspecies
Considered by some authors to be a subspecies of Japanese Bush-Warbler (Horornis diphone).
The following 2 subspecies are recognised:
canturians (Swinhoe, 1860) - Central, eastern China, south-eastern Siberia and Korea. Considered by some authors to be a subspecies of Japanese Bush-Warbler (Horornis diphone).
borealis (Campbell, CW, 1892) - Breeds north-eastern China, adjacent south-eastern Russia (southern Ussuriland) and Korea. Non-breeding eastern China (Fujian), Taiwan and northern Philippines (Batan Is, Luzon). Considered by some authors to be a distinct species, Manchurian Bush-Warbler (Horornis borealis). Considered by some authors to be a subspecies of Japanese Bush-Warbler (Horornis diphone).
BirdLife International Species Factsheet