Habitat
Wet areas of thick grasses and reeds and in areas of low bushes. In wintering range, in extensive reedbeds, low shrubs near reedbeds and mangroves. From sea-level - 350 m.
China (mainland) (P), Hong Kong (China) (NB), Japan (B), Russia (Asian) (B), South Korea (B).
Vagrant to North Korea.
Breeds on islands in extreme south-eastern Russia (islets in Peter the Great Bay, in southern Ussuriland), southern Korea (Ullung I, off eastern coast, also small islands off southern & western coasts) and southern Japan (Izu Is, also small islands off south-western Honshu and Kyushu), probably also coastal northern Korea; non-breeding in coastal south-eastern China and northern Vietnam.
Rarity Status
Currently this species is not classified as a rarity in this country OR information has not been updated.
Population
Estimated population is 2,500 - 9,999 (2010) and decreasing.
Similar Species
Middendorff's Grasshopper-Warbler (Locustella ochotensis) which has browner mantle and scapulars, more noticeable supercilium and eye-stripe and pale outer web to the long, outermost primary. Generally paler underparts.
References
See References.
BirdLife International Species Factsheet