Willow warbler: the bird profiles

Willow warblers and chiffchaffs are easy to confuse. And really how loud is a warbler’s song? Here’s everything you should know about the willow warbler.

The willow warbler (Phylloscopus trochilus) belongs to the leaf warbler genus. Though widespread in Europe, and native to the UK, the songbird’s plain appearance is easy to overlook. And even if you do manage to spot one, willow warblers are often confused with their far more common relative: the chiffchaff. If you are lucky enough to see a willow warbler in your garden, listen out for a delightful, melodic song. Read on to discover more about this fascinating bird, how you can support it, and how to distinguish it from its famous relative, the chiffchaff.

Willow warbler: key facts

How to recognise the willow warbler

Willow warblers are rather inconspicuous garden birds. Their backs, heads and wings are coated olive-green. Their undersides are tinged a pale yellow. Their cheeks have subtle, yellow patches. And just above their eyes sit some yellow stripes, which are highlighted with slight, dark lines. Unfortunately, it is close to impossible to tell the difference between male and female willow warblers.

How to tell the difference between the willow warbler and the chiffchaff

The willow warbler and chiffchaff are difficult to tell apart. One point of difference, however, is the colour of their legs. The willow warbler’s legs are bright orange, whilst the chiffchaff’s are dark. What is more, willow warblers tend to have longer, lighter stripes above their eyes than chiffchaffs, making them more distinct. But these differences are subtle, and sensitive to light conditions. Really, the best way to tell a willow warbler from a chiffchaff is to listen. Willow warbler’s have a melodic, trilling song, while the chiffchaff sings a loud, two-syllable “chiff-chaff-chiff-chaff”.

How to recognise a young willow warbler

Young willow warblers look very much like their parents, though they tend to have more yellow feathers. The adult’s breast is predominantly yellow but blends to a dirty white at the belly. A willow warbler chick, on the other hand, has a completely yellow underside.

How to recognise a willow warbler egg

Females lay between 4 and 7 eggs per clutch. The eggs are about 1.4 cm long, white and speckled light brown. They are laid in a nest of moss, grass, twigs and plant fibre, which is padded with fine feathers and hair.

What is the perfect habitat for willow warblers?

Willow warblers look for areas of dense vegetation. This includes sparse deciduous and mixed forests, meadows, orchards, farmland that is bounded with hedgerows and groves, parks, and large, wild gardens.

Where do willow warblers build their nests?

Willow warblers build their nests in hedges and shrubs. The nest tends to have a roof and side entrance, much like a small oven, and is built very low to the ground. So low in fact, that sometimes it is constructed on the ground. Its proximity to the ground makes it an easy target for cats and other predators. As such, the nests tend to be hidden in very dense vegetation.

When is breeding season for willow warblers?

Willow warblers breed between May and July and tend to raise only 1 brood per year. The eggs are incubated for 12 to 14 days, and the hatchlings are fed in the nest for 2 weeks. Following this, young warbler chicks explore their surroundings, supported by their parents for a while, before they are left to fend for themselves.

Where do willow warblers spend winter?

Since willow warblers feed mainly on insects, there isn’t food for them in the UK over winter. As such, the warblers migrate long distances in late summer to southern Africa, returning to the UK only in April.

What does a willow warbler’s song sound like?

Willow warblers have a distinct, melodic song. It consists of a few bright, clear whistling tones that start quickly, drop in pitch, and finish with longer notes. In contrast to its song, the warbler’s call – “hu-itt” – is less distinct and easy to confuse with other bird calls.

Help the willow warbler!

Due to agricultural intensification and urbanisation, it is increasingly difficult for willow warblers to find a suitable habitat. As such, the songbirds are finding themselves in parks and gardens. Read on to find out how you can make a bird-friendly garden and support your local willow warblers.

What do willow warblers eat?

Willow warblers feed mainly on insects picked from leaves and twigs. They are also partial to berries and fruits and other small animals, such as spiders and molluscs. Unfortunately, standard bird feed containing grain and seed does nothing for the small songbirds. Not least because they do not remain in the UK over winter, so winter feed is redundant.

But do not despair! By fostering an insect-friendly garden, the warblers will have plenty of food. With a few simple steps, you can attract a variety of tiny visitors to your garden and provide a rich, natural food supply for many birds.

Which birdhouses are suitable for willow warblers?

Willow warblers prefer to build their own nests. This means a traditional birdhouse, as used by blue tits and redstarts, is unlikely to do much for a willow warbler. Instead, try offering natural nesting sites in the form of shrubs and hedges. And avoid trimming woody plants too much as willow warblers need the dense vegetation to protect their nests from intruders.

How can I support willow warblers even more?

Many wild birds are experiencing waning food supplies and a decline in their natural habitat. The problems are serious and large-scale, but we can all do our part. Start in the garden by avoiding chemical sprays. These sprays reduce insect populations and can even poison birds.

Another insectivore that fills the air with its lovely song is the blackcap. Find out more about this intriguing warbler in our species profile.