Perdeck A.C. (1958) Two types of orientation in migrating Starlings, Sturnus vulgaris L., and Chaffinches, Fringilla coelebs L., as revealed by displacement experiments. ARDEA 46 (1-2): 1-37

1. From 1948-1957 more than 11,000 marked Starlings (one-third adults, two-thirds juveniles), caught during autumn migration near The Hague, and were (by airplane) displaced to Switzerland (Basle, Zurich and Geneva). They yielded 354 recoveries. 2. Ringing has shown that these Starlings belong to populations breeding in South Finland, South Sweden, the Baltic area and adjoining Russian parts, North Poland, North Germany, Denmark and Holland. They winter in Holland, West Belgium, N.W. France, South England and Ireland. The birds breeding in Holland are not the same as those wintering there. The preferred direction of autumn migration in Holland is about W.S.W. -W. (field observations). 3. After the displacement juveniles and adults held a different course. The adults aimed at the original wintering area in a N.W. direction (S.W. courses only at shorter distances). The juveniles flew in a direction quite similar to the preferred direction normal in Holland (a small shift to the south is discussed). They wintered in Southern France and the Iberian Peninsula. The conclusion drawn is that during autumn migration, adult Starlings use a true goal orientation (homing orientation), the juveniles a one-direction orientation. 4. No significant differences were found in the directions of the birds when juveniles and adults were released together or separately (at different places). As is pointed out, this does not imply that an influence of the age-groups on each other is lacking in natural flocks. 5. Recoveries from later seasons showed that the adults had come back in the original area of distribution; the juveniles, however, had a clear tendency to remain wintering in the area reached after their displacement. The breeding area of the juveniles was within the normal range, with a shift to the east. It is concluded that Starlings are able to fix their winter quarters in their first year, with an ability to reach it in later years by means of true goal orientation. 6. A similar experiment was carried out with Chaffinches (migrants through Holland belonging to the Scandinavian population, wintering in the British Isles). 1,250 Chaffinches (900 adults, 350 juveniles) caught in autumn near The Hague were transported to Switzerland. In the same season they yielded 2 recoveries of juveniles (from Southern France: 535 km S.W. by W., 440 km S.W.) and 1 recovery of an adult (from England: 915 km W.N.W.). The same phenomenon as found in the Starling is suggested by these recoveries: juveniles fly parallel to original course (one-direction orientation) adults direct themselves to the original wintering area (true goal orientation). 7. The implications of these results are discussed, especially with reference to the influence of leading lines (natural displacement!) and the concept of the 'preferred direction'.