Biogeography and history of the Mediterranean bird fauna

With 366 species of breeding birds, the Mediterranean region is a “hot spot” of species diversity. Many biogeographic realms contributed to the establishment of the extant fauna, which makes this region a crossroads for birds, but the two most important realms are the large forest blocks that extend today over Eurasia and the semi‐arid belts of the southern and southwestern Palaearctic. The few groups that presumably differentiated within the Mediterranean basin are mostly birds of open habitats and shrublands (e.g. Sylvia spp.), whereas few species evolved in Mediterranean forests dominated by sclerophyllous evergreen tree species. We suggest this results from the history of vegetation belts and their associated faunas during the Pleistocene. On the whole, in contrast to other groups of vertebrates, the bird fauna is fairly homogeneously distributed all over the basin although there are some regional‐specific trends in species assemblages, mostly on the basis of habitat selection and biogeographic origin. Many species of eastern and southeastern origin invaded the Mediterranean basin on the northern side of the sea up to the Balkan peninsula and the southern side to the Atlantic coast. The extant biogeographic patterns of the Mediterranean bird fauna are interpreted in the light of the Quaternary history shared by the biotas of the western Palaearctic in relation to the cycle of climatic changes which produced periodic huge spatiotemporal migrations of communities and populations. The severe human impact that started c. 8000‐10,000 years ago resulted not so much in species extinctions as in dramatic changes in distributional patterns, complicating the reconstruction of biogeographic scenarios.