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Willow warbler (Phylloscopus trochilus)

These dainty birds with a delightful song are our most common and widespread warbler.

Common name: willow warbler

Scientific name: Phylloscopus trochilus

Family: Sylviidae (warblers)

Appearance

Head: The species has a brownish cap, with a pale yellowish-green stripe above the eye.

Wings: Long primary feathers give this bird a long-winged appearance, reflecting the long distances it travels on migration. The wings are brown with hints of yellow and green.

Body: The breast has a yellowish or olive green colour with paler underparts. With a typical weight of around nine grams, this is a dainty bird of similar size to a blue tit.

Not to be confused with

The willow warbler looks very similar to the chiffchaff, but can be distinguished by its song. The former has a beautiful liquid warble with a sad descending melody that rises in volume. Chiffchaffs make a ‘chiff-chaff’ sound, which earned the species its name. Willow warblers are also a brighter yellowish-green in colour and have pale pink legs (chiffchaffs have dark brown or black legs). However, spotting these differences on a bird as they flit about the branches is very difficult.

Where to spot

A summer visitor, arriving from March onwards, willow warblers can be found in almost any patch of woodland or scrub. They leave the UK between July and September to spend the winter in Africa, south of the Sahara.

Feeding

Willow warblers eat a wide variety of small insects and spiders, as well as fruit and berries in the autumn. They often sing and shake their wings while foraging for insects.

Breeding

Willow warblers build distinctive, dome-shaped nests with a hole in the side, close to the ground. Into these oven-like nests, very small eggs are laid - so tiny that three eggs weigh the same as a penny combined. The smooth, glossy white eggs are speckled with reddish-brown. The female incubates the eggs by herself, but after the young hatch they are fed by both parents.

Facts

  • Unusually for birds, willow warblers moult their feathers twice a year.
  • The number of willow warblers breeding in the UK has fallen by 44% since 1970.

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