Scientific name: Phylloscopus borealis (Blasius, 1858)
Bird group: Warblers
Field characters. 12 cm. Slightly larger than Willow Warbler. Upperparts green or greyish green, duller than Greenish Warbler. Flight feathers with greenish wash, underparts white or greyish-white. Most obvious field marks are long white supercilium, almost starting at base of bill and ending in neck (does not reach the bill as in Greenish Warbler); one white wing-bar (sometimes a second in autumn); heavily mottled ear-coverts; and pale legs (paler than Greenish Warbler). Rear end of supercilium often curved upwards. Sexes similar. Juvenile greener and brighter coloured than adult in autumn.
Voice. Call 'tzik', sometimes bisyllabic. Song a monotonous trill.
Distribution. Rare and irregular summer visitor.
Habitat. Dense birch-thickets on slopes and in gullies, often near water.
Food. Insects.