The hypothesis is tested whether the Atlantic between NW Africa and th
e south coast of the Iberian Peninsula is crossed in spring by passeri
ne trans-Saharan migrants only in easterly winds because of drift or p
seudodrift. The analysis is based on the number of daily captured bird
s during spring migration 1983 and 1986 at a ringing station in Sanluc
ar de Barrameda, situated at the Spanish south coast. Maximum numbers
of captured birds occured only during periods of several days with eas
terly winds at the bottom and high.