The chestnut-flanked white-eye (Zosterops erythropleurus ) is a bird in the family Zosteropidae. The species was first described by Robert Swinhoe in 1863. It is found in forests, and prefers rather deep mixed and coniferous forests.
It is 10.5 cm in length and has a distinct chestnut patch on its flanks. The bill base and lower mandible may be pinkish. Its underparts are whiter. The similar Japanese white-eye is pale brown on its flanks.
It is migratory, breeding in Manchuria and migrating to central China, the province of Yunnan and northern Southeast Asia in the winter. It is the most migratory species of white-eye. It breeds in poplar, alder and willow forests, thickets and groves, and winters in deciduous and evergreen forests, usually above 1000 m.
