Willow Warbler

The willow warbler, Phylloscopus trochilus, presents itself as a rather unassuming yet charming leaf warbler. This small passerine measures between 11–12.5 cm in length and tips the scales at a delicate 7–15 g. Its plumage is a subtle greenish brown above, while below, it ranges from off-white to a gentle yellowish hue. The wings are a consistent greenish-brown, devoid of any wingbars, contributing to its understated elegance.

Identification Tips

Distinguishing the willow warbler from its congeners, particularly the chiffchaff, can be a delightful challenge. Look for its paler pinkish-yellow legs, a contrast to the chiffchaff's darker limbs. The willow warbler's bill is longer and paler, and its overall shape is more refined. The primary projection, or wingtip, is notably longer, aiding in its identification. Juveniles tend to be more yellow below than their adult counterparts.

Habitat

The willow warbler favors open woodlands replete with trees and ground cover suitable for nesting. It shows a particular fondness for birch, alder, and willow habitats. The proximity to the ground is crucial for its nesting sites, often chosen within low vegetation.

Distribution

A true voyager, the willow warbler breeds across northern and temperate Europe and the Palearctic, stretching from Ireland to the Anadyr River basin in eastern Siberia. Come winter, the species migrates en masse to the warmer climes of sub-Saharan Africa.

Behaviour

The willow warbler is a highly migratory species, embarking on seasonal journeys that are remarkable for a bird of its size. It is one of the earliest warblers to herald the arrival of spring in northern Europe, though it lags slightly behind the chiffchaff. The breeding season typically yields one brood, with a rare second on occasion.

Song & Calls

The willow warbler's song is a simple, melodious descending whistle, evoking the essence of spring. Its contact call is a distinctive disyllabic 'hoo-eet', which can be used to differentiate it from the more monosyllabic 'hweet' of the chiffchaff.

Breeding

Nesting close to the ground, often in low vegetation, the willow warbler's breeding habits are a testament to its connection with the earth. The breeding season spans from late April to August, with the birds usually producing a single brood.

Similar Species

The chiffchaff is the willow warbler's closest look-alike, but careful observation of leg color, bill length, body shape, and primary projection can help keen birdwatchers tell them apart.

Diet and Feeding

Insectivorous by nature, the willow warbler partakes in a diet consisting primarily of insects, which it deftly plucks from leaves and branches in its woodland home.

Conservation status

The IUCN Red List currently classifies the willow warbler as Least Concern, reflecting its widespread distribution and abundant population. However, regional declines, particularly in England, highlight the importance of habitat management and conservation efforts to ensure this species continues to grace our woodlands.