Wood Warbler - Willow Warbler.

The wood warbler and the willow warbler are part of a group of birds known collectively as the leaf warblers. When the leaf warblers arrive back in the UK the countryside is enhanced by their zest for life, and their pleasant singing reverberating around the tree tops.

Leaf warblers are small insectivorous birds belonging, in the main, to the genus Phylloscopus placed in the family Phylloscopidae, a family only created in 2006. The two warblers under review here are the wood warbler Phylloscopus sibilatrix and the willow warbler P. trochilus. the other genus in this family is the Seicercus which contains about 11 species.  They all belong to the Order Passeriformes {perching birds}. 

Wood warbler. Image courtesy of Steve Garvie {Scotland} CC BY-SA 2.0 License

Wood Warbler-Phylloscopus sibilatrix

The wood warbler is a widespread a relatively common warbler that breeds throughout northern and temperate Europe. They over winter in Africa. However, here in the UK there have been some worrying declines in population numbers {see conservation issues below.}

                              DESCRIPTION OF THE WOOD WARBLER.

This is one of the larger members of the genus Phylloscopus and one with warmer colours with areas of lemon and clear green. It is much restricted inhabiting high woodland with open space beneath the trees.

The wood warbler has a thick black line through the eye with a long yellow stripe above it. 

Wood warbler chicks in nest.

Courtesy of Algirdas {Lithuania} CC BY -SA 3.0 License.

The upper plumage is of a clear green colour. The wings are brownish with pale yellowish feather edges. The long wing tips are often drooped besides the tail. The under parts are silky white, the breast is yellow. The bill is thin and of a brownish colour, the legs pale yellowish.

In relation to its body size the wings are medium long, the tail medium, neck short, bill short, legs medium long. The movement of the wood warbler is a restless and flitting always on the move either skulking in the under growth or among the tree canopy.

They are 13 cm {5 inches} long with a wing span of 19-24 cm { seven and a half to nine and a half inches} and weigh 7-12 gms.

Its voice is a fast metallic trill which is delivered with gusto, making the birds whole body quiver. The call note is mellow and plaintive.

The bird can be told from all other warblers by its larger size, eye stripe and yellow and white under parts.

Lifestyle and breeding

The wood warbler is a bird of open but shady woodland, favouring woodland of beech and sessile oak, where it feed on insects and other invertebrates and some fruit later in the season. The latter is to build up their strength for the long journey back to tropical Africa which commences in late September as a rule.

When the bird arrives back in Britain, during April in the south or May in the north, its warbling song is used to mark out their territories as they flit among the foliage and undergrowth. When a pair is established a nest is constructed.

The wood warbler formerly known as the wood wren, nests on the ground among the undergrowth in woods, making a nest similar to those of the willow warbler and chiffchaff, both in form and materials, it is a domed nest of dry leaves, grasses etc, however, feathers are rarely found in the interior. It is somewhat surprising that a bird as arboreal in nature as the wood warbler builds its nest on or very close to the ground.

The eggs have a white background speckled dark brown which vary in amount, however, they are generally well distributed intermingled with grey spots as well. They number 5-7 the first usually being encountered in May. Incubation is carried out by the female and takes around 13 days. They fledge in a further 13 days. They raise just one large family, however, replacement clutches will be laid. They are old enough to breed at one year.  


photograph courtesy of Andreas Trepte CC BY-SA 3.0 License.

Willow warbler-much commoner warbler.

This species is a much more common and widespread species which was once on the list of common British birds. They breed right across Eurasia as far as the Pacific coast, and yet all of them migrate to Africa.


The willow warbler is not much bigger than a bluetit they are graceful and slim. Olive coloured above and yellow below, and the only striking character is the creamy coloured eye stripe. The crown has no markings. This greenish brown colouring may be dull but it makes for excellent camouflage among the foliage of trees and shrubs that it inhabits, and also when they nest among the dense vegetation.

The tail is a uniform brown without any markings of any kind. Willow warblers have pale coloured legs. In relation to its body size the wings are medium length, the tail is medium long, the neck short, the bill thin and short and the legs medium length.

The movement , typical of the leaf warblers, is restless and flitting. The flight is somewhat bounding. On the ground and in trees it hops. They are 11-12.5cm long with a wing span of 22cm and weigh 7-15gs -they are at their heaviest before migration. 

Life style and breeding of the willow warbler.

The willow warbler is a bird of the woods and other well timbered and bushy places, such as heaths, commons, shrubberies and large gardens. Despite their common name they do show any preference for willow trees. like the former species it nests on the ground despite spending much of its time in the tree tops. the nest is usually placed in a slight depression and often situated among bramble for security and concealment.

The nest is large and rough looking and also like the former species the nest is domed. The materials used  are moss, hay or some other such like material among which feathers are prominent.

The eggs may be as few as five or as many as seven. they are white, usually speckled with pale clear, red, the speckling may vary in distribution and from a liberal sprinkling to hardly any at all. The first batch may be found towards the end of April but in June a second brood may well be encountered. The eggs are incubated by the female for 13-14 days. The chicks are born blind, downy and helpless.  Fledging occurs in a further 13-14 days.

The diet of the willow warbler is mainly insects and spiders picked from the surface of the leaves.as with the former species fruit is eaten to build up their fat reserves for the long migration to Africa which occurs in late September.

willow warber in spring tree

photo courtesy of Rob Bendall  CC BY-SA 3.0 License


Globally and European wise the birds are of Least Concern as far as conservation is concerned. However, here in the UK the wood warbler is on the Amber list of conservation concern because of declines in population numbers of between 25-50%.

The latest figures { courtesy of the BTO } is for the year 2000 when the willow warbler was estimated at 2,125,000 territories and the Wood warbler 9,000 -10,500 pairs.

It is thought that the declines are still on going. Latest updates in population figures will occur here as they are published. 

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UK conservation status 2021

UK- Willow warbler-Amber listed -due to declines in population/distribution of over 25% in the last forty years or so 

Europe-Species of least concern.

Wood Warbler-UK- Red listed due to declines of over 50% in population/distribution  over the last forty years or so.

Europe-Species of least concern 

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