Phylloscopus orientalis (C.L.Brehm, 1855)

Taxonomic Classification

Eastern Bonelli's warbler (Phylloscopus orientalis), sometimes called the Balkan warbler, is a species of warbler in the leaf warbler genus Phylloscopus.

Previous Taxonomic Treatment

It was previously classified as the eastern subspecies of a broader, combined "Bonelli's warbler" species, but modern taxonomic revisions now treat this group as two separate species: Western Bonelli's warbler (Phylloscopus bonelli), which breeds in southwestern Europe and northern Africa, and Eastern Bonelli's warbler (Phylloscopus orientalis), which breeds in southeastern Europe and Asia Minor.

Breeding Range Separation

The breeding ranges of these two species do not overlap.

Species Differentiation Traits

While their appearance and songs are very similar, their calls are completely different, and they also show marked differences in their mtDNA sequences.

Migratory Pattern

This species is migratory, and spends the winter in sub-Saharan Africa.

Vagrant Occurrence

It is a rare vagrant in Northern Europe.

Habitat

Eastern Bonelli's warbler is a small passerine bird that inhabits forest and woodland.

Reproduction

It lays four to six eggs in a nest built on the ground.

Diet

Like most warblers, Eastern Bonelli's warbler is insectivorous.

Adult Plumage

Adults have a plain grey-green back, green-toned rump and wings, and whitish underparts.

Morphological Features

They have a small pointed bill and brown legs.

Sexual Dimorphism

As with most warblers, the sexes are identical in appearance.

Plumage Comparison to Western Species

Compared to Western Bonelli's warbler, Eastern Bonelli's warbler lacks the brownish tinge on its upperparts, and sometimes has a greenish tinge instead.

Song Characteristics

The song of Eastern Bonelli's warbler is a fast monotone trill, which is only slightly different from the song of Western Bonelli's warbler, and also has some similarity to the song of the wood warbler.

Call Characteristics

The call of Eastern Bonelli's warbler is a hard chup, which resembles the call of a crossbill or a house sparrow, and is completely different from the disyllabic hu-it call of Western Bonelli's warbler.

Genus Name Etymology

The genus name Phylloscopus comes from Ancient Greek: phullon means "leaf", and skopos means "seeker" (from skopeo, meaning "to watch").

Specific Epithet Etymology

The specific epithet orientalis is Latin for "eastern".

Common Name Etymology

The English common name honors the Italian ornithologist Franco Andrea Bonelli.