China (mainland), Indonesia, Japan, Mongolia, North Korea, Papua New Guinea, Philippines, Russia (Asian), Russia (Central Asian) (B), South Korea, Taiwan (China).
Vagrant to Denmark, France.
Population
Estimated population is unknown (2010).
Gray's Grasshopper Warbler (Helopsaltes fasciolatus) [XC151723]
by Mike Nelson from Weda, Central Halmahera, North Maluku, Indonesia (call)
Gray's Grasshopper Warbler (Helopsaltes fasciolatus) [XC438342]
by Stanislas Wroza from Kabansky Zakaznik, Buryatiya Republits, Russian Federation (song)
Subspecies
Forms a species group with Pallas's Warbler (Locustella certhiola), Middendorff's Grasshopper-Warbler (Locustella ochotensis) and Pleske's Warbler (Locustella pleskei) and it is also suggested that Marsh Grassbird (Locustella pryeri) is part of this group and should therefore be moved to present genus. Subspecies amnicola may warrant full species status.
The following 2 subspecies are recognised:
fasciolata (Gray, 1860) - Breeds south-central Siberia (from east of upper R Ob') east to south-eastern Russia (Amurland, Ussuriland) and north-eastern China. Non-breeding Philippines, Sulawesi, Moluccas and western New Guinea.
amnicola Stepanyan, 1972 - Sakhalin, southern Kuril Islands and Hokkaido. Winters in Philippines. Considered by some authors to be a distinct species, Sakhalin Warbler (Locustella amnicola).