Bonelli's Warbler is a "warbler" in the leaf warbler genus Phylloscopus. As a result of modern taxonomic developments, it is now usually considered to be two species (Sangster et al. 2002, Parkin 2003):
- Western Bonelli's Warbler, Phylloscopus bonelli, which breeds in south west Europe and north Africa
- Eastern Bonelli's Warbler, Phylloscopus orientalis, which breeds in south east Europe and Asia Minor
Their breeding ranges do not overlap; while their appearance and songs are very similar, the calls are completely different (see below). They also show marked difference in mtDNA sequence (Helbig et al. 1995).
Both species are migratory, wintering in sub-Saharan Africa. They are both rare vagrants in Northern Europe.
These small passerine birds are found in forest and woodland. 4-6 eggs are laid in a nest on the ground. Like most warblers, Bonelli's is insectivorous.
These are small warblers. The adults of both species have a plain grey-green back, green-toned rump and wings and whitish underparts. The bill is small and pointed and the legs brown. The sexes are identical, as with most warblers.
The Western Bonelli's Warbler has a browner tinge to the upperparts than Eastern Bonelli's Warbler; the latter sometimes has a greenish tinge instead. The song of both species is a fast monotone trill, with only slight differences between the two, and also some similarity to Wood Warbler. The call of the Western Bonelli's Warbler is a disyllabic hu-it, that of the Eastern a completely different hard chup, reminiscent of a Crossbill or a House Sparrow.(Helb et al. 1982)
This bird is named after the Italian ornithologist Franco Andrea Bonelli.