# UKBirds

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## Eastern Bonelli's Warbler

### Phylloscopus orientalis

Eastern Bonelli's Warbler (sometimes known as Balkan Warbler) is a "warbler" in the leaf warbler genus Phylloscopus. It was formerly regarded as the eastern subspecies of a wider "Bonelli's Warbler" species, but as a result of modern taxonomic developments, this species 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
The breeding ranges of the two species 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).
The species is migratory, wintering in sub-Saharan Africa. It is a rare vagrant in Northern Europe.
Eastern Bonelli's Warbler is a small passerine bird, found in forest and woodland. 4-6 eggs are laid in a nest on the ground. Like most warblers, Eastern Bonelli's is insectivorous.
It is a small warbler. The adult has 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 Eastern Bonelli's Warbler lacks the browner tinge to the upperparts that Western Bonelli's Warbler has; it sometimes has a greenish tinge instead. The song is a fast monotone trill, only slightly different from Western Bonelli's, and also some similarity to Wood Warbler. The call of the Eastern Bonelli's Warbler is a hard chup, reminiscent of a Crossbill or a House Sparrow, and completely different from the disyllabic hu-it of Western.(Helb et al. 1982)
This bird is named after the Italian ornithologist Franco Andrea Bonelli.