Western Bonelli's Warbler

The Western Bonelli's Warbler, Phylloscopus bonelli, is a diminutive and active leaf warbler, flitting through the foliage in search of insects. This species, named after the Italian ornithologist Franco Andrea Bonelli, is adorned with a plain grey-green back, a green-toned rump and wings, and whitish underparts. Both sexes are identical in plumage, which is typical for warblers.

Identification Tips

When identifying the Western Bonelli's Warbler, look for its small, pointed bill and brown legs. The upperparts may have a subtle brownish hue, distinguishing it from its eastern counterpart, which may instead exhibit a greenish tinge.

Habitat

This warbler favors forests and woodlands, where it can be seen actively foraging among the leaves.

Distribution

The Western Bonelli's Warbler breeds in southwest Europe and north Africa. It is a migratory bird, wintering in sub-Saharan Africa, and occasionally appears as a rare vagrant in Northern Europe.

Behaviour

During the breeding season, the Western Bonelli's Warbler lays four to six eggs in a ground nest. The eggs are white with reddish-brown markings, typically in clutches of 3-5. Incubation lasts about 14 days, and the young fledge in 10-14 days. Cuckoo nest predation and brood parasitism pose significant threats to their breeding success.

Song & Calls

The song of the Western Bonelli's Warbler is a fast monotone trill, bearing resemblance to the wood warbler's song but with slight differences from the Eastern Bonelli's Warbler. Its call is a distinctive disyllabic 'hu-it', which is notably different from the 'chup' call of the Eastern Bonelli's Warbler.

Diet and Feeding

Insectivorous by nature, the Western Bonelli's Warbler is typically seen gleaning insects from leaves and branches.

Conservation status

The IUCN Red List classifies the Western Bonelli's Warbler as Least Concern, indicating that the species currently faces no imminent threat to its survival.