Gray-cheeked Warbler Phylloscopus poliogenys Scientific name definitions

c. 10–11 cm; one bird 6·3 g. Has crown, nape, ear-coverts and lateral margin of throat dull grey, lores dull grey with some whitish admixed; lateral crownstripe dark grey, contrasting rather poorly with rest of crown/nape; broad white eyering broken anteriorly above eye; upperparts green; upperwing and tail brown-grey with green feather edges, whitish or pale yellowish tips of greater upperwing-coverts (forming distinct pale wingbar); prominent white wedges on inner webs of three outermost pairs of rectrices; bright yellow below, variable amount of pale greenish on breast side and, often, flanks, and diffusely greyish-white upper throat; iris dark brown; bill blackish, base of lower mandible pale greyish-pink; legs greyish-pink or pale brownish. Distinguished from P. intermedius by less contrasting crown pattern, all-grey ear-coverts, greyish-white upper throat, no yellow on lores and anterior eyering, three pairs of rectrices white, and dark-tipped lower mandible; from P. burkii, P. whistleri and P. tephrocephalus by e.g. mainly grey head and white, broken eyering. Sexes similar in plumage, female on average smaller than male. Juvenile has almost unicoloured grey crown, slightly greenish forehead, and is brownish-yellow below, slightly paler on throat.

Insects known to be taken, but no detailed studies of diet. Forages primarily in understorey .

Song consists of short (c. 0·8–1·7 seconds) strophes of varied whistled notes usually arranged in phrases (element groups) of 2–3 elements, each phrase given 2–6 times, the phrases often rather quick and trilling (but fast single-element trills rare), and single strophes often consist of two or more different phrases (more complex, “irregular” strophes also given); e.g. “tsui-tsi-tsui-tsi-tsvitsvitsvitsvi… tseet tsi-tseet-tsi-tsutsutsutsu… tsiu-wis-tsiu-wis-sisisi… tsy tsi-tsy-tslytslytslytslytsly… tsui-si-tsui-si-tsui-si-tsui-si… tsui-tsi-tsui-tsi-tsvitsvitsvitsvi… tsui-si-tsui-si-tsui-si-tsui-si-tsui-si…”; some geographical variation apparent, Himalyan birds having more complex songs than those in C & S Vietnam, although this has not been thoroughly studied; song resembles that of P. burkii but generally higher-pitched, with longer, more complex and more trilling strophes; much higher-pitched and covers broader frequency band than that of P. intermedius, and higher-pitched and less rattling than that of P. tephrocephalus. Call apparently geographically variable, in Himalayas a high-pitched rising “ueest”, reminiscent of call of P. inornatus, and in C & S Vietnam a high-pitched falling “tseeu”; both easily separable from calls of congeners.