Willow Warbler Bird Facts (Phylloscopus trochilus)

Visual Identification

Appearance

The Willow Warbler is a small, slender bird with olive-green upperparts and pale yellow underparts. It has a distinctive pale supercilium (eyebrow stripe) and a thin, pointed bill.

Males and females are virtually identical in appearance. Juveniles are similar to adults but have a slightly yellower overall plumage. The species shows little seasonal variation in its plumage.

Size

Length

11cm to 12.5cm

Wingspan

16cm to 22cm

Weight

7g to 15g

Colours

Males and females have similar plumage

Primary Colour

Olive Yellow

Secondary Colour

White Brown

Beak Colour

Brown

Leg Colour

Brown

Habitat and Distribution

Habitats

Woodland

The Willow Warbler can be found in Woodland habitats.

Garden

The Willow Warbler can be found in Garden habitats.

Wetland

The Willow Warbler is not typically found in Wetland habitats.

Coastal

The Willow Warbler is not typically found in Coastal habitats.

Urban

The Willow Warbler is not typically found in Urban habitats.

Farmland

The Willow Warbler is not typically found in Farmland habitats.

Grassland

The Willow Warbler is not typically found in Grassland habitats.

Desert

The Willow Warbler is not typically found in Desert habitats.

Tundra

The Willow Warbler is not typically found in Tundra habitats.

Rainforest

The Willow Warbler is not typically found in Rainforest habitats.

Mountain

The Willow Warbler is not typically found in Mountain habitats.

Savanna

The Willow Warbler is not typically found in Savanna habitats.

Distribution

Willow Warblers inhabit open woodlands, forest edges, and scrubland across much of Europe and western Asia. They prefer areas with birch, willow, and other deciduous trees mixed with undergrowth.

As long-distance migrants, they winter in sub-Saharan Africa. In the UK, they are widespread summer visitors, arriving in spring and departing by early autumn.

Elevation Range

Sea level to 1,000 meters

Climate zones

Temperate, Subarctic

Distribution Map

This map gives you a rough idea of where you might spot a Willow Warbler. The coloured areas show countries where these birds have been seen.

A few things to keep in mind:

Birds might not be everywhere in the coloured areas, for example, they may be present around the coast of that country
Where birds live can change with seasons and available food
This map is quite simple - it doesn't show exact locations

We're working on making our maps even better! Soon, we hope to show you:

More detailed maps for bigger countries, including state and region
How birds move around during different seasons

Resident

Breeding

Passage

Vagrant

Distribution by Region

Species that are present in the area during their breeding season

Afghanistan Albania Austria Belarus Belgium Bulgaria Croatia Czech Republic Estonia Faroe Islands France Georgia Hungary Ireland Kazakhstan Latvia Liechtenstein Lithuania Luxembourg Macedonia Moldova Montenegro Netherlands Norway Poland Portugal Romania Russia Serbia Slovakia Slovenia Spain Sweden Switzerland The United Kingdom Turkey

Species that pass through the area during migration

Bahrain Iran Iraq Italy Jordan Kuwait Lebanon Oman Qatar Saudi Arabia South Sudan Syria Turkmenistan United Arab Emirates Yemen

Species that appear infrequently (rare) and unpredictably outside their normal range

Canada Comoros Greenland India Japan Saint Helena, Ascension and Tristan da Cunha Seychelles Svalbard and Jan Mayen Islands

Behaviour and Ecology

Bird Attributes

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Bird Attributes Explained

Our bird attributes system rates various aspects of a bird's capabilities on a scale of 0-100, based on data from field observations, scientific studies, and expert knowledge.

Attribute Categories:

Agility: Manoeuvrability, speed, and grace in flight or movement.
Strength: Physical power, often correlating with size and hunting abilities.
Adaptability: Ability to thrive in various environments or changing conditions.
Aggressiveness: Territorial behaviour and assertiveness, particularly during breeding seasons.
Endurance: Stamina, often seen in migration patterns or foraging behaviours.

Understanding the Ratings:

0-20: Very Low
21-40: Low
41-60: Average
61-80: High
81-100: Very High

Remember, these attributes are relative to other bird species and don't necessarily indicate superiority.

Hover over the icon next to each attribute for more information.

Tap the icon next to each attribute for more information.

Agility 85

Agility

Reflects the bird's manoeuvrability, speed, and grace in flight or movement.

The Willow Warbler demonstrates remarkable agility, frequently hovering whilst foraging and adeptly flitting through foliage. Their active nature and ability to glean insects from leaves and branches, often in mid-air, indicates a high level of manoeuvrability and dexterity.

Strength 20

Strength

Indicates the bird's physical power, often correlating with size and hunting abilities.

As a small passerine weighing between 7-15 grams, the Willow Warbler possesses limited physical strength. However, their ability to undertake long-distance migrations suggests a degree of muscular endurance despite their diminutive size.

Adaptability 80

Adaptability

Represents the bird's ability to thrive in various environments or changing conditions.

Willow Warblers exhibit considerable adaptability, inhabiting various environments from sea level to 1,000 metres elevation. Their capacity to thrive in diverse habitats across Europe and western Asia, coupled with their successful long-distance migration to sub-Saharan Africa, demonstrates significant adaptive capabilities.

Aggressiveness 40

Aggressiveness

Measures the bird's territorial behaviour and assertiveness, particularly during breeding seasons.

Whilst not overtly aggressive, male Willow Warblers vigorously defend their territories during the breeding season through song and displays. This behaviour indicates a moderate level of aggression, primarily confined to territorial defence rather than general temperament.

Endurance 90

Endurance

Reflects the bird's stamina, often seen in migration patterns or foraging behaviours.

The Willow Warbler's endurance is particularly noteworthy. Their ability to undertake annual migrations of up to 12,000 km (7,456 miles), coupled with their active foraging behaviour and the energy demands of breeding, suggests exceptional stamina for a bird of this size.

Diet

Willow Warblers primarily feed on small insects and spiders. They glean prey from leaves and branches, often hovering to reach items on the undersides of foliage. In autumn, they may supplement their diet with small berries and fruits to build fat reserves for migration.

Insect eggs also form a large part of their diet. Insects are caught mainly from the tree canopy but may also be hunted on the ground.

Behaviour

Willow Warblers are active and agile birds, often seen flitting through foliage in search of insects. They frequently hover while foraging, plucking prey from leaves.

During the breeding season, males establish and vigorously defend territories through song and displays.

Vocalisation

The literary definition of the word ‘warbler’ itself is a melodic sequence. Willow Warblers, like all warblers, are named as such because they are capable of melodic songs.

The Willow Warbler's song is a sweet, melodious warble that descends in pitch, often ending with a flourish. It can be described as a soft 'tsuu-ee-tsuu-ee-tsuu-ee-tsu-u-u'. Their call is a soft, plaintive 'hoo-eet' or 'hoo-ee'. The pitch is lower than birds of similar size.

Nesting & Breeding

Breeding occurs from April to July. Males attract females with their melodious songs and aerial displays. Pairs are monogamous during the breeding season.

The female builds a domed nest on or near the ground, hidden in dense vegetation. The nest is made of grass, leaves, and moss, lined with feathers. A typical clutch consists of 5-6 white eggs with reddish-brown spots.

Incubation lasts about 13-14 days, performed mainly by the female. Both parents feed the chicks, which fledge after 12-14 days. Pairs often raise two broods per season.

Conservation and Status

Global Conservation Status

Least Concern ^[1]

While currently listed as Least Concern globally, Willow Warbler populations have declined in parts of Europe, including the UK. Habitat loss in both breeding and wintering grounds, as well as climate change impacts, are potential threats.

Conservation efforts focus on maintaining suitable breeding habitats.

Population Data

Global Population Estimate

413,000,000 - 647,000,000 mature individuals ^[2]

Global Population Trend

^[3]

Trend data may be uncertain or fluctuating

Additional Information

Quick Facts

Other names:

Willow Wren

Family:

Phylloscopidae

Average Lifespan

2 to 4 years

Max Lifespan

11.8 years ^[4]

Predators

Main predators include sparrowhawks, domestic cats, and small mammals such as weasels and stoats. Nest predators may include jays, magpies, and rodents.

Did You Know?

Willow Warblers can fly up to 12,000 km (7,456 miles) during their annual migration, one of the longest by any songbird.
They are one of the most numerous summer migrants in the UK, with over 2 million breeding pairs.
Despite their name, they are not closely related to New World warblers.

References

1 2
website: BirdLife International. 2016. Phylloscopus trochilus. The IUCN Red List of Threatened Species 2016: e.T22715240A87636348.
View source
3
report, 2015: EBCC
4
website, 2010: Fransson et al., EURING list of longevity records for European birds Publication type
View source