The bird fauna of the Mediterranean area is analyzed from an ecological and biogeographical point of view. In the first part of this paper, the distribution of the 335 species so far recorded in the region is analyzed according to some ecological standards and relevant theories of island biogeograohy, such as the relationships between richness and area (mediterranean islands), the mechanisms of dispersion. In relation to the patterns of habitat selection by the species, their icological characteristics and so forth. The second part deals with the biogeographical composition of the bird faunas and their history since the glacial times. It is shown that the mediterranean bird fauna of the present times derive from three main complexes : a palaearctic and holarctic stock whick makes up the great bulk of forest and fresh water birds, a palaearctic-steppic and semi-arid fauna originating from the arid belt encircling to the south and the east the mediterranean basin and an autochtonous but far less abundant truly mediterranean avifauna which evolved in evergreen mediterranean habitats. Many clues (mainly paleobotanical and paleontological) strongly suggest that the birds of the present times did remain in the meditarranean area even at the height of the last glaciation.