Pallas's grasshopper warbler 
also known as the rusty-rumped warbler
(Chích đầm lầy lớn, Helopsaltes certhiola)

Pallas's grasshopper warbler (Helopsaltes certhiola), also known as the rusty-rumped warbler, is an Old World warbler in the grass warbler genus Helopsaltes, the family Locustellidae.

The bird breeds in the eastern Palearctic: from the Altai Mountains, Mongolia and Transbaikalia to northeastern China, the Korean Peninsula, and islands in the Sea of Okhotsk (Sakhalin and Kuril Islands). It is migratory, wintering from India eastward to Indonesia.

Locustellidae, Locustella is from Latin and is a diminutive of locusta, "grasshopper".
The genus name Helopsaltes combines the Ancient Greek helos meaning "marshy ground" and psaltis "a chanter".
The specific certhiola is a diminutive from the genus Certhia, the treecreepers.