Nijhoff P. (1958) Herfstwaarnemingen bij Cap Gris-nez. ARDEA 46 (1-2): 62-67

During the autumn-migration the well-known coasting movements of North-European Starlings and Chaffinches in Holland and Belgium are continued to Cap Gris-Nez, where the coast-line abruptly turns to S. (see fig. 1). It was found that the crossing to S.B. England was not made in the originally preferred direction W. to S.W., but the position of the wintering area proved to influence the direction to W. to N.W. (also see van Dobben 1944; Lack 1954). It is supposed this applies to Rooks too. These directions are not induced by the occasional visibility of the coast of Kent as the birds chose them too when this coast was invisible. The above observations correspond with the results of the displacement experiments of the Foundation 'Vogeltrekstation Texel', which have proved that the preferred direction of Starlings has underlying orientation- mechanisms different in adult and young birds, viz., a true goal orientation and a one-direction orientation, respectively (Perdeck 1958). The adults influencing the direction of the young birds are very likely.