a. Flight paths

The whole world is criss-crossed with the flight-paths of migrating birds. ‘Almost all areas between the Artic and Antarctic are used as breeding grounds. Migrants also regularly reach even the most remote corners of the earth for non-breeding periods’²

Fig. 1 A summary of bird migration paths in the Old world.

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The shortest route from ‘breeding’ to ‘feeding’ grounds may not be the best, or most energy efficient route. Birds may need to take a circuitous route to stop off and moult or regain fat-reserves. Barriers to migration may need to be avoided. In the Old World, mountain ranges, the Mediterranean and the Sahara all lie perpendicular to the general north-south migration direction. White storks migrating from northern Europe to South Africa are not able to cross the Alps, the Mediterranean and the Sahara successively. Migration routes have evolved in many species to circumnavigate such chains of obstacles. Consequently the routes converge at geographical bottlenecks where barriers can be crossed at their narrowest point. Such areas, often used by thousands of individuals and myriads of species, are known as flyways.

This section looks at the importance of the western crossing of the Mediterranean at Tarifa for the Palaearctic migration.