Willow Warbler (10–11cm, 4–4½in)

 

The Willow Warbler, a small, greenish warbler, enjoys widespread distribution across Europe during the summer months. Arriving in late March or early April, they grace the continent until their departure in September and October. Unlike their close relatives, the Chiffchaffs, Willow Warblers rarely overwinter in Britain.

Habitat: A Preference for Youthful Greenery

While sharing similar habitats with Chiffchaffs, Willow Warblers gravitate towards smaller, younger trees, bushes, and ground vegetation. They can be spotted in tranquil woodland edges, gardens bordering woodlands, or even slightly overgrown gardens.

Distinguishing Features: Subtleties in a Verdant Palette

The small Willow Warbler closely resembles the stouter Chiffchaff. However, several key features aid in identification:

• Structure:

  • The Willow Warbler boasts longer wings compared to the Chiffchaff's shorter ones.

  • Leg color is a giveaway – pale in Willow Warblers and dark in Chiffchaffs.

• Plumage:

  • Overall: Willow Warblers generally appear paler than Chiffchaffs, especially in spring.

  • Head and Upperparts: Pale olive-green with a long, yellow-tinged eyebrow (supercilium) – unlike the short, buff one of the Chiffchaff. They also have a thin, dark eyestripe and faintly speckled cheeks.

  • Wings: Pale olive, except for darker primary feathers.

  • Tail: Dark.

  • Underparts: Cleaner than the Chiffchaff’s, lacking buff tones. The breast and flanks are washed in pale yellow, contrasting with a whitish belly.

• Bill: Dark upper mandible and tip, with a flesh-pink lower mandible.

• Eyes: Black, with a less prominent ring than the Chiffchaff.

• Legs: Pale flesh.

• Song: A fluid series of descending notes culminating in a quick flourish.

• Call Note: Similar to the Chiffchaff's but more piercing and melodic, described as a "hoo-eet".

Variations on a Theme: Not All Willow Warblers are Created Equal

• 'Northern' Willow Warblers: Occasionally, strikingly pale individuals, known as 'northern' Willow Warblers, appear in Britain. Their overall plumage is a washed-out greenish, except for darker primary feathers, tail tip, and eyestripe. They possess an off-white supercilium and underparts, with a greyish wash on the flanks. Beware of confusing these with rarer warblers!

• Autumn Plumage: Adult Willow Warblers in autumn might appear slightly browner on top and more yellow underneath.

• Juvenile Plumage: Some young Willow Warblers sport a striking autumn plumage. Their upperparts are pale olive-green, while their underparts, from face and throat to undertail coverts, are a rich lemon-yellow. The belly typically remains whitish.

The Willow Warbler, with its subtle beauty and remarkable camouflage, is a testament to the diversity within seemingly similar species. Learning to differentiate them from their Chiffchaff cousins adds a rewarding dimension to birdwatching.