Looks very much like a chiffchaff, and best identified by voice: song is pleasant, slightly descending warble, very different from song of chiffchaff. Compared to chiffchaff, Willow Warbler is often brighter, more yellowish (especially in autumn) with stronger pale eyebrow, pinkish legs, and tends not to habitually dip its tail. However, many birds seen are best left unidentified. Found in wooded habitats, from mixed forest to willow thickets in open country.