Willow Warbler 

(Phylloscopus trochilus)

Alert Status: Amber - 67% decline

Identifying Features: Willow warblers are small birds with grey-green backs and pale under parts. They have a yellow tinged chest and throat and pale supercillium (the stripe above the eye). Similar features to a chiff chaff but often with paler legs.
Average Length: 10-11.5 cm
Average Lifespan: 2 years
Average Wingspan: 16-22 cm
Beak type: Insects

 

Feeding:
Natural: Small insects and spiders, fruit and berries in Autumn

 

Nesting: The domed nest, made from grass, rotten wood, moss and roots, is on the ground among shrubs or grass. The nest has a side entrance and is lined with fine roots and feathers.

 

Where to see: Willow warblers are widespread and can be seen in suitable habitat across most of the UK.
 

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Willow Warbler song by Dominic Garcia-Ha
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Fascinating Facts

Another of our summer visitors, the willow warbler arrives in the UK during April and will leave again around August or September, for Southern Africa. These small birds are grey-green above and their underparts are pale with a yellow tinged chest and throat. They have a brownish head with a pale yellow-green stripe above the eye. Long primary feathers on its wings give this little bird a long-winged appearance. 

The willow warbler can easily be mistaken for a chiffchaff as they look very similar. Although willow warblers have pale legs and chiffchaffs legs are dark grey, it is far easier to separate the two by their song. Willow warblers have a lovely warble that descends in scale whereas the chiffchaff makes a ‘chiff-chaff’ sound. 

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Being one of our most common summer visitors you can spot them in open woodlands, scrub land, parks, and gardens. Willow warblers feed on a variety of small insects and spiders picked from leaves and twigs. They are partial to fruits and berries in the autumn.

 

Once arrived in the UK many, nest building commences! Willow warblers build dome-shaped nests with an entrance hole in the side. The nests are built close to the ground in hedges and shrubs and are made of moss, grass, twigs and plant fibre, finally being lined with feathers and hair.

Breeding takes place between May and July and willow warblers tend to raise only one brood per year. The small white eggs are speckled with brown. Incubation is done by the female and takes around twelve to fourteen days and the hatchlings are fed in the nest for two weeks, by both parents. 

Willow warbler nest - Keith Cowieson Low Res.jpg

Unusually, the willow warbler moults twice a year – once at their breeding grounds and once at their wintering grounds. The reason for this is unclear.

 

The willow warbler likes to sing and shake its feathers while it forages for insects!

The typical weight of a willow warbler is just 9 grams. 

A willow warblers eggs are so tiny that three of them weigh about the same as a penny! 

A group of warblers has many collective names including a bouquet, a confusion, a fall and wrench.