oscarps
In order to avoid a long passage of the Mediterranean Sea, the birds of central Europe either follow a route of oriental migration – in which they cross the Bosporus in Turkey, they cross the Levant, and follow the Nile towards the south of the valley, avoiding the desert of the Sahara – either follow a western route through the Straits of Gibraltar. These migratory corridors maximize the use of thermals and thus save energy.
