Larger than Chiffchaff, with much stronger bill, larger head, broader back, and sturdiest.
Large, rather large-headed and fairly plump Phylloscopus, with distinctive bill, short rounded wings, rather large and slightly rounded tail, and strikingly heavy legs and feet.
Plumage subtly but richly colored, green to brown-olive above, buff and yellow below, with long, deep pale supercilium, dark eye and eye-stripe, and bright sheen over wings. Calls distinctive.
Sexes similar, quite marked plumage variation due to age and wear.
Breeds in central and east Palearctic in warm continental middle and lower middle latitudes in open forests, glades, clearings, regrowth in burnt and felled patches, strips of trees along riversides, and willow beds on lake shores and islands.
Spends most time in undergrowth and surrounding grasses and herbage, ascending to treetops only in breeding season.
the thresholds for the population decline criterion of the IUCN Red List (i.e. declining more than 30% in ten years or three generations). For these reasons, the species is evaluated as Least Concern.
Migratory, wintering in south-east Asia. Leaves breeding grounds mostly late August to mid-September. Spring migration through China mostly May to early June, arriving on Siberian breeding grounds about 2nd week of June.
Autumn vagrancy to western Europe, resulting from reverse migration or westward displacement in anti-cyclonic conditions, is less frequent than in some Asiatic Phylloscopus; spring records exceptional. In Britain and Ireland, 49 records 1958-85, all 26 September to 1 November.