Most distinct species of the genus. Most similar to Willow Warbler, but with much more contrasting plumage. Upperparts pure green. Throat and upper chest yellow, contrasting with pure white underparts. Distinct and strong yellow supercilium and black eye-stripe. Long primary projection, with primaries reaching middle of relatively short tail. Tertials with pale green fringes. Legs pale yellowish brown. Posture often horizontal with drooping wings.

Song distinct. An accelerating series of sharp, metallic "swee-swee-swee-swee". Typically with a staccato beginning. Pitch drops as the speed increases and the syllables fuses into a continuous trill. Often described as the sound of a spinning coin coming to rest on a glass table. Some phrases may be given in an almost even tempo, and may recall Bonelli's Warbler. Alternative (piping) song a series of 4-6 piping, plaintive and descending "pew - pew" calls. Resembles Willow Tit's song, but is softer with each note more evenly pitched. Contact call similar to individual syllables of piping song, but with heavier accent on the ending.

Song (two variants):

Wikipedia: map (se also Xeno-canto below)

Birdlife ecology

Observation.org Latest observations

Video IBC

Image search Flickr NB! May give other species

Sound search at Xeno-canto

Featherbase