Willow Warbler Phylloscopus trochilus breeds Ireland to Siberia, with either acredula or yakutensis possibly breeding in Altai Mountains in Xinjiang. Winters sub-Saharan Africa. Slender, long-winged, green and yellow. Frequently confused with Common Chiffchaff P. collybita, being best distinguished by voice; distinguished visually by better-marked head (more distinct, longer, and yellower supercilium, longer eye-stripe), cleaner and whiter underparts with contrast between yellow breast and yellowish-white belly, paler bill and feet, and longer primary projection. Juveniles have bright-yellow underparts. Song soft and sweetly descending. Call similar to Common Redstart, a soft and slightly upturned huit, softer and with less emphasis on second syllable than Common Chiffchaff. — Craig Brelsford
Daniel Bengtsson served as chief ornithological consultant for Craig Brelsford’s Photographic Field Guide to the Birds of China, from which this species description is drawn.