Abstract
Radar observations of passerine trans-Saharan migrants during autumn migration (August and September 1981, 1983, 1984, and 1985) in the Straits of Gibraltar revealed intense movements to the south and southwest. On average birds flew to the southwest (211°). Thus, after crossing the coast of southwestern Europe, migrants did not change their direction to the southeast towards the interior of Africa. If the birds maintained their southwesterly direction, they would continue along the west coast of Africa. Along this route the birds might find better conditions than on any route through the interior of the continent.
The reported average direction of birds at Gibraltar represents a sample of the general behavior pattern in the southern Iberian Peninsula. The variance of nightly directions could be explained by the fact that birds fly on a fixed heading in strong crosswinds that alternate between east and west, but are only of local importance on a southbound migration route.