brown bush warbler Locustella luteoventris

Shy inhabitant of scrubby areas in the middle to upper reaches of hilly and montane regions. Dark brown with a white throat and grayish belly. Long tail usually held horizontally, seldom cocked up. Rarely ventures out into the open except when singing; even then, it usually sings from partial cover. Song is a rattling series of dry, repeated notes, somewhat like clattering machinery.