It is a typical leaf warbler in appearance, 11-12.5 cm long and 7-15 g weight. It is greenish brown above and off-white to yellowish below; the wings are plain greenish-brown with no wingbars. Juveniles are yellower below than adults. It is very similar to the Chiffchaff, but non-singing birds can be distinguished from that species by their paler pinkish-yellow legs (dark brown to blackish in Chiffchaff), longer paler bill, more elegant shape and longer primary projection (wingtip).


Habitat and Distribution

The Willow warbler breeds throughout northern and temperate Europe and Asia, from Ireland east to the Anadyr River basin in eastern Siberia. It is migratory, with almost all of the population wintering in sub-Saharan Africa. They prefer young, open, scrubby woodland with small trees, including human-altered habitats such as coppice and young plantations. High amounts of birch, alder and willow, with good lichen amounts, and water features (e.g. streams) are important.


Feeding

This small passerine is insectivorous.


Breeding

They need trees and ground cover for nesting, including most importantly birch, alder, and willow habitats. The nest is usually built in close contact with the ground, often in low vegetation.


Calls and Songs

Its song is a simple repetitive descending whistle, while the contact call is a disyllabic 'hoo-eet', distinct from the more monosyllabic 'hweet' of Chiffchaffs.