Timing, age classes and water-crossing behaviour of Black Kites (Milvus migrans) during spring migration across the Central Mediterranean

The main migratory passage of Black Kites across the Mediterranean Sea occurs at the Strait of Gibraltar, where the migration peak is observed in early March. Conversely, in the Central Mediterranean the migration of this species is scarce during the supposed peak period, while hundreds of individuals are observed migrating later in the season, mostly in April and May. In the present study we investigate the spring migration of Black Kites at two sites of the Central Mediterranean, the island of Ustica and the Strait of Messina. Timing, age classes and water-crossing behaviour of this species suggest that large numbers of non-breeders use this route during spring. However, a peculiar migration timing of breeding pairs belonging to the Italian population cannot be excluded.