White-spectacled Warbler Phylloscopus intermedius Scientific name definitions

11–12 cm. Race zosterops has “bright” grey median crownstripe, black lateral crownstripe (usually distinct on forehead, almost to bill); sides of crown and nape (below lateral crownstripe) and upper ear-coverts grey, lower ear-coverts usually green, sometimes greyish-green or greenish-grey (and then contrasting very slightly with upper ear-coverts/neck side); lores green, usually with some pale yellow admixed; distinct white eyering broken anteriorly above eye, usually with some pale yellow in front of eye; upperparts green; upperwing and tail brown-grey with green feather edges, tips of greater upperwing-coverts pale yellow (forming distinct pale wingbar), prominent white wedges on inner webs of two outermost pairs of rectrices; bright yellow below, variable amount of pale greenish on breast side and, often, flanks; iris dark brown; upper mandible blackish, lower mandible pale orange; legs pale greyish-pink. Distinguished from P. poliogenys by paler and purer grey crown with more contrasting lateral crownstripes, green lower ear-coverts, yellow on lores and anterior eyering, all-yellow throat, lack of white on third outermost rectrix, and entirely pale orange lower mandible; from P. burkii and P. whistleri by e.g. white broken eyering. Sexes similar in plumage, female on average smaller than male. Juvenile is greenish-tinged on crown and ear-coverts, with less distinct lateral crownstripes than adult’s, and paler, less intense and more dusky yellow below. Race ocularis is indistinguishable from zosterops, separable only by geographical location; nominate intermedius differs chiefly in having yellow eyering, occurs as two morphs (intermediates exist), one with crown pattern much as zosterops but slightly less grey on sides, not reaching onto ear-coverts, and forehead usually green, the other (“cognitus”) with green, instead of grey on crown.

Editor's Note: This article requires further editing work to merge existing content into the appropriate Subspecies sections. Please bear with us while this update takes place.

Previously placed in Seicercus; see Phylloscopidae. MtDNA data suggest that populations from Sichuan and Guangdong, currently grouped in race intermedius on plumage, may be more closely related to race ocularis than to topotypical intermedius from Fujian (1 Olsson, U., Alström, P. and Sundberg, P. (2004). Non-monophyly of the avian genus Seicercus (Aves: Sylviidae) revealed by mitochondrial DNA. Zool. Scripta 33(6): 501–510. Close ); further research required to test relationships and to see if additional taxa may be involved, perhaps even at species level (2 Martens, J. (2010). A preliminary review of the leaf warbler genera Phylloscopus and Seicercus. British Ornithologists' Club Occasional Publications 5:41–116. Close ). Situation of S race ocularis unclear and it has variously been grouped with W or E races; may be morphologically and vocally very similar to Himalayan birds, despite wide geographical separation, but has been suggested as possibly worth consideration for biological species status (3 Rheindt, F.E. (2006). Splits galore: the revolution in Asian leaf warbler systematics. BirdingASIA 5: 25–39. Close ); further study needed, but for present it seems best to keep this taxon separate. Birds from NW Fujian described as race cognitus, but considered to represent a colour morph of intermedius, co-occurring over much of range (1 Olsson, U., Alström, P. and Sundberg, P. (2004). Non-monophyly of the avian genus Seicercus (Aves: Sylviidae) revealed by mitochondrial DNA. Zool. Scripta 33(6): 501–510. Close ). With merging of Seicercus and Phylloscopus, name affinis (previously nominate form of present species) becomes preoccupied; recently replaced by new name zosterops (4 del Hoyo, J., and N. J. Collar (2016). HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions, Barcelona, Spain. Close ), while intermedius now has priority and becomes the new nominate form. Three subspecies tentatively recognized.

Editor's Note: Additional distribution information for this taxon can be found in the 'Subspecies' article above. In the future we will develop a range-wide distribution article.

Breeds in upper part of tropical, mostly evergreen, broadleaf forest zone to lower part of cool temperate zone with mainly deciduous broadleaf forest; favours lush undergrowth in mature forest. Has been recorded in breeding season at c. 1400–2600 m in Himalayas, c. 1500–2000 m in S Vietnam, and c. 1000–1750 m in China.

Race zosterops an altitudinal migrant, descending to foothills and edge of plains in non-breeding season. Nominate intermedius has been recorded in winter from within its breeding range, but also from Hong Kong, Vietnam and Laos.

Diet insects; no details. Forages mainly in understorey; catching of prey often involves short flights.

Song consists of short (c. 1–1·9 seconds) strophes of varied whistled clear notes, usually begins with 1–2 disconnected notes, followed by repetition of the same and/or 1–4 different notes, and ends with doubled or tripled phrase of 2–3 elements (“slow trill”) or a fast single-element trill, so that song seems to begin somewhat hesitantly and then accelerate, and strophes separated by pauses usually several seconds long, e.g. “uee-tiu uee-tiu-chu-weet-chu-weet-chu-weet… tsueet tsueet-tsi-didididididididididi… ueet ueet-tsi-tsu-tsu-tsu-tsu-tsu… tsu-weet tsu-weet-tswee-tswee-tswee… uu-wee-chu uu-wee-dididididi… chu-du chu-du-tsee-duee-tsee-duee… chu-du chu-du-tsee-duee-tsee-duee… uu-weet tee-tiu-uu-weet tiurrrrrrr…”; simpler variants also given; contains much higher proportion of trills than song of P. poliogenys, and differs further from that, and also from songs of P. tephrocephalus and P. omeiensis, in being lower-pitched, covering narrower frequency band, and beginning more falteringly. Calls variable, probably at least partly geographically, but improperly known; e.g. a quick rising “u-di-si”, whistled “ty-týý-sit”, “ty-týú” and “ty-týéé” (zosterops), soft rolling “trri-trri-trri” or “trru-trru-trru” (ocularis), slow soft clear whistled “ti-tiuu-tit” or “ti tiuu-it”, rolling and whistled “eerrr chu-it”, soft slightly rolling “ti-tirr”, and drawn-out rolling note ending in multiple whistle, “churrrruwedichi” (nominate intermedius); strikingly different from calls of congeners.

Little studied. Season Apr–Jun in Himalayas; in China, males sing mainly mid-Apr to early Jun. Nest (of race zosterops) a ball of moss, rootlets and a few leaves, lined with fine vegetable down, placed in hollow or in dense moss on steep bank, occasionally in tree hole. Clutch 4–5 eggs; incubation by both sexes. No further details.

Not globally threatened. Rather scarce throughout its range, but no population estimates.