- Phylloscopus trochilus
Length 11-12.5cm (4¼-5 in), weight 6.3-14.6 g
- Greenish-yellowish-brown back,
- Pale underparts, tinged yellow on throat and breast
- Pale yellowish-white supercillium
- Thin brown bill
- Brownish-yellow or light brown legs (although this is variable to some extent).
- Primary extension usually about 75%, cf chiffchaff
Juvenile and 1st Winter:
- Much yellower supercillium and underparts
Widespread and abundant in the northern half of Europe and western Asia, scarcer towards northeastern Asia.
Breeds throughout the British Isles, Scandinavia and northern Russia south to central and south-east France, Switzerland and Austria, northern parts of Hungary and Romania, and east between about 50°N and 68°N across Russia.
Arrives on the breeding areas mainly in April (late March in the south, May or even June in the far northeast), returning south in August-September, passage continuing until October, wintering in sub-Saharan Africa. Abundant on passage over most of Europe, the Middle East and North Africa. Birds from the far east of Siberia migrate over 15,000 km to winter in South Africa; in proportion to its size (125 million body lengths!), the longest migration of any bird.
There are 3 subspecies:
- P. t. trochilus: the most greeny-yellow subspecies; descrived above
- P. t. acredula: similar to nominate but duller and paler below with less yellow on underparts of juvenile.
- P. t. yakutensis: drabber still, light grey-brown above and whitish below
- Eastern Siberia (Taymyr Peninsula to Anadyr River); winters to southern Africa. Occurs as a migrant across central Asia and southeast Europe, and rarely as far west as Britain, but P. t. acredula can appear very similar.
Open deciduous woodland, bushy areas, parks and gardens. Also in mixed forest and young conifer plantations, hedgerows and shelterbelts. On passage occurs in all types of habitat with trees and bushes.
The diet includes small insects and spiders and fruit and berries.
The domed nest has a side entrance and is formed from grass, rotten wood, moss and roots, lined with feathers. It is placed on the ground amongst shrubs or long grass. The clutch consists of 3-9 smooth, glossy white eggs, speckled reddish-brown. The female incubates for around 13 days. Both adults feed the young, which fledge after about 13-16 days.
Listen in an external program [[Media:Phylloscopus trochilus (song).mp3|Willow Warbler song clip]
- Clements, J. F., T. S. Schulenberg, M. J. Iliff, D. Roberson, T. A. Fredericks, B. L. Sullivan, and C. L. Wood. 2018. The eBird/Clements checklist of birds of the world: v2018. Downloaded from http://www.birds.cornell.edu/clementschecklist/download/
- Clement, P. (2018). Willow Warbler (Phylloscopus trochilus). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/58860 on 12 October 2018).
- Howell, S.N.G., Lewington, W. & Russell, W. (2014) Rare Birds of North America. Princeton Univ. Press.
- Collins Pocket Guide to British Birds 1966
- Collins Bird Guide ISBN 0 00 219728 6
- British Garden Birds
- BirdForum Opus contributors. (2021) Willow Warbler. In: BirdForum, the forum for wild birds and birding. Retrieved 31 July 2021 from https://www.birdforum.net/wiki/Willow_Warbler