By Mariano Gómez · Updated on 9 October 2026

Birds

Willow Warbler, the yellowish traveller we only see on passage

Phylloscopus trochilusHear its song0:28

Photo gallery of the Willow Warbler

Identification of the Willow Warbler

The Willow Warbler is very like its relatives, above all the Common and Iberian Chiffchaffs, from which it differs in having pale bill and legs, more marked face stripes with a very evident supercilium, more yellow underparts and a brighter greenish tone on the back.

Adult

• Pale bill and legs.
• More marked face stripes and very evident supercilium.
• Underparts more yellow and back brighter green.

Habitat and distribution of the Willow Warbler

It is distributed widely and continuously across the temperate, boreal and Arctic latitudes of the whole of Europe and Asia. It is absent or appears very locally in southern Europe. Three subspecies are recognised.

In the III Atlas of Breeding Birds in Spain its presence could not be confirmed with signs or behaviour of breeding, which means the disappearance of this warbler as a breeder compared with earlier studies. During migration passage it can be found throughout Spain; both the subspecies «trochilus», from western Europe, and «acredula», originating in Scandinavia, appear.

It is a species tied to woodland and scrub environments: it usually occupies thinned woods, edges or clearings of woodland, regenerating woods and various shrubby and scrub formations. During migration passage it can be found in a wide variety of habitats, as long as they provide some kind of plant cover.

It is a migrant, with winter quarters that extend across almost all of sub-Saharan Africa, from Senegal to Ethiopia in the east and to South Africa in the south. An important contingent from central and northern Europe crosses the Peninsula, the Balearics and the Canaries during passage. The pre-breeding passage is detected between March and May, with a peak in late April, and the post-breeding one between August and November, with the largest number of birds in early September, on a more westerly route across the Peninsula.

Etymology of the Willow Warbler

According to Wikipedia, «Phylloscopus» comes from ancient Greek «phúllon» («leaf») and «skopós» («the one who looks»), and «trochilus» is the Greek word for «wren» or «goldcrest». In other languages it is called «mosquiter de passa» in Catalan, «picafollas musical» in Galician, «txio horia» in Basque and «willow warbler» in English¹.

Population of the Willow Warbler

In the 2021 European Red List of Birds the European breeding population is estimated at between 106,000,000 and 161,000,000 mature individuals, with a decreasing trend. In Spain it is considered only a passage visitor, with no population data to report. No observations of the species as a breeder have been recorded, but not because it suffers specific threats, but because of environmental (temperature, humidity) and biogeographical limitations¹.

Nest of the Willow Warbler

In its breeding area, the nest, built by the female, consists of a small cup of leaves, branches and moss, set in the thicket of shrubby or tree vegetation. It does not breed in Spain.

Courtship and breeding of the Willow Warbler

In its breeding area the breeding period runs from May to July, and pairs normally make a single clutch, occasionally two. The clutch is three to nine whitish eggs, speckled with light brown to varying degrees, which the female incubates for 12–14 days. The chicks are usually tended by both parents, are able to fly at 11–16 days and reach independence 12–16 days later. It does not breed in Spain.

Diet of the Willow Warbler

It feeds mainly on small insects and spiders. In autumn it may also eat small berries, such as blackberries or elderberries.

Curious facts about the Willow Warbler

Of the species of leaf warblers that visit us during migration passage, the Willow Warbler is perhaps the most abundant, being one of the most numerous birds in the whole of Europe. According to Wikipedia it makes one of the longest migrations of any animal of its size. EURING lists a bird ringed in the Netherlands that lived 18 years and 8 months, a figure out of line with AnAge’s 11.8 years and with the 13 years and 10 months of another bird on the same list (Germany).

The Willow Warbler in Cabañeros

The habitat pages of this website do not mention it. GBIF.org records 102 observations of the Willow Warbler in Cabañeros and its surroundings, which correspond to migration passages, because it does not breed in Spain.

Where to see the Willow Warbler in Cabañeros

In Cabañeros and its surroundings, on migration passage.

When

On passage: the pre-breeding one, from March to May (with a peak in late April) and the post-breeding one, from August to November (with a peak in early September).

What time

In good light, in thinned woods, tree edges and scrub; on passage it can appear in any habitat with plant cover.

Where

On the branches of trees and shrubs, always on the move.

What to look for

Look for the pale bill and legs, the pale eyebrow and the yellowish tone; listen for its descending phrase.

Videos of the Willow Warbler

Similar species

Common Chiffchaff

Phylloscopus collybita

How to tell them apart

It is very similar in song and appearance¹. The Willow Warbler is told by its pale bill and legs, more marked face stripes, more yellow underparts and greener, brighter back.

Photo: Jacob Spinks from Northamptonshire, England, CC BY 2.0

Iberian Chiffchaff

Phylloscopus ibericus

How to tell them apart

It is very similar in song and appearance¹.

Photo: Sébastien FAILLON, CC BY 2.0

Other birds

Bibliography

• Jiménez García-Herrera, José. (2017). Aves de Cabañeros y su entorno. Madrid, Spain: Ecohábitat.
• SEO Birdlife - Sociedad Española de Ornitología
• https://es.wikipedia.org/
• Hume, Rob. (2016). Guía de campo de las Aves de España y Europa. Barcelona, Spain: Ediciones Omega