Chestnut-flanked White-eye Zosterops erythropleurus Scientific name definitions

10·5–11·5 cm; 10–13 g. Male has black lores, olive side of the head, well-developed white eyering broken at front; olive-yellow above, rump and uppertail coverts more yellow; closed wings like back; tail greyish-brown, feathers edged olive; throat bright lemon-yellow, clearly demarcated from pale grey side of breast, centre of underparts white, flanks chestnut (sometimes rather faint); iris dark brown; bill brown above, bluish below; legs greyish. Female is like male, but lores dusky, chestnut of flanks often very faint, sometimes no more than a faint pinkish suffusion. Juvenile undescribed.

Extreme SE Russia (E Amurland, Ussuriland) and NE China (Heilongjiang), possibly reaching extreme N Korea; non-breeding S China, Myanmar, Thailand, NW Vietnam, Laos and Cambodia.

Breeding habitat includes groves, bushes, poplars (Populus), alder (Alnus) thickets, willow (Salix) jungles along riverbanks, streams and lakes. In non-breeding area deciduous or broadleaf evergreen forest, secondary growth; from foothills to 2590 m, most often above 800–1000 m.

The most migratory species in family. Leaves breeding grounds in Sept, main stream of migrants passing S (mainly W of Korea) through S Gansu and E Sichuan; normal wintering areas include S China (Sichuan, Yunnan), W, C & E Myanmar (Nov–Apr), Cambodia, N & C Laos (regular visitor), N Thailand (fairly common), and N Vietnam (W & E Tonkin, where seems to prefer mountains). Small numbers sometimes found during summer in winter quarters. Accidental in coastal areas and islands in Sea of Japan (records in Oct, Nov, Feb, and May), but may prove to be a rare but annual migrant there. Recorded in E Mongolia in Apr (1 Baatargal, O. and Suuri, B. (2013). Chestnut-flanked White-eye Zosterops erythropleurus: first record for Mongolia. BirdingASIA. 20: 111–112. Close ). Distances flown, twice a year, up to 3500 km; one in Bokor (S Cambodia) would have migrated 5000 km from breeding area.

Feeds on insects. Usually in flocks, sometimes mixed with other small passerines, e.g. Northern Long-tailed Tits (Aegithalos caudatus).

Loud song. Loud piercing, monosyllabic “tsee” (“lost-chick” call), or “tseeplee”.

Little known. Season probably end May to Aug; fledglings found in Aug, also four fledglings attended by three adults in elm (Ulmus) woodland in Jun. Nest in tree; clutch 5–6 eggs. No other information.

Not globally threatened. Fairly common locally; not numerous on its breeding grounds. Large numbers seen in China, where many captured for food and cagebird trade. Recorded as a migrant in Pangquangou National Nature Reserve, in China (Shaanxi).