The western Bonelli's warbler (Phylloscopus bonelli) 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, they are now usually considered to be two species:[2][3]
Western Bonelli's warbler, Phylloscopus bonelli, which breeds in southwest Europe and north Africa
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 mtDNAsequence.[4]
The species is migratory, wintering in sub-SaharanAfrica. It is a rare vagrant in Northern Europe.
The genus name Phylloscopus is from Ancient Greekphullon, "leaf", and skopos, "seeker" (from skopeo, "to watch").[5] The English name and the specific bonelli are for the Italian ornithologist Franco Andrea Bonelli.[6]
Western Bonelli's warbler is a small passerinebird, found in forest and woodland. Four to six eggs are laid in a nest on the ground. The eggs are white with reddish-brown markings and are laid in clutches of 3-5 eggs. The incubation period is around 14 days long, and the chicks fledge after 10-14 days.[7] Cuckoo nest predation and brood parasitism are major hazards to the breeding success of western Bonelli's warblers.[8] Like most warblers, western Bonelli's warbler is insectivorous.
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 western Bonelli's warbler has a browner tinge to the upperparts than the eastern Bonelli's warbler; the latter sometimes has a greenish tinge instead. The song is a fast monotone trill, only slightly different from eastern Bonelli's, and also with some similarity to the wood warbler. The call of the western Bonelli's warbler is a disyllabic hu-it, differing from that of the eastern Bonelli's warbler which is a hard chup, reminiscent of a crossbill or a house sparrow.[9]
^Helbig, A. J.; Seibold, I.; Martens, J. & Wink, M. (1995): Genetic differentiation and phylogenetic relationships of Bonelli's Warbler Phylloscopus bonelli and Green Warbler P. nitidus. J. Avian Biol.26: 139–153.
^Helb, H.-W.; Bergmann, H.-H. & Martens, J. (1982): Acoustic differences between populations of western and eastern Bonelli's Warblers (Phylloscopus bonelli, Sylviidae). Cellular and Molecular Life Sciences38(3): 356–357.
