About Phylloscopus trochilus (Linnaeus, 1758)
Taxonomic Naming
The willow warbler, Phylloscopus trochilus (Linnaeus, 1758), is a typical leaf warbler in overall appearance.
Size Measurements
It measures 11–12.5 cm (4.3–4.9 in) in length and weighs 7–15 g (0.25–0.53 oz).
Adult Plumage
Its upperparts are greenish brown, and its underparts range from off-white to yellowish. The plain greenish-brown wings have no wingbars.
Juvenile Plumage
Juvenile willow warblers have yellower underparts than adult birds.
Similar Species Comparison
This species is very similar in appearance to the chiffchaff.
Visual Identification Differences
Non-singing willow warblers can be told apart from chiffchaffs by several features: paler pinkish-yellow legs (chiffchaffs have dark brown to blackish legs), a longer paler bill, a more elegant body shape, and a longer primary projection on the wingtip.
Species Song
The willow warbler's song is a simple repetitive descending whistle.
Contact Call Differences
Its contact call is a disyllabic 'hoo-eet', which is distinct from the more monosyllabic 'hweet' contact call of chiffchaffs.
