The Western Bonelli's warbler is a warbler in the leaf warbler genus Phylloscopus. It was formerly regarded as the western 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: 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 MinorThe 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.The species is migratory, wintering in sub-Saharan Africa. It is a rare vagrant in Northern Europe. The genus name Phylloscopus is from Ancient Greek phullon, "leaf", and skopos, "seeker" (from skopeo, "to watch"). The English name and the specific bonelli are for the Italian ornithologist Franco Andrea Bonelli.