Migratory orientation of first-year white storks (Ciconia ciconia): inherited information and social interactions.

We used satellite tracking to study the migratory orientation of juvenile white storks from the population in the Kaliningrad Region (Russia) during their first autumn migration. Two series of experiments were performed. In the first series of experiments, several groups of first-year storks were raised in an aviary, kept there until all free-living conspecifics had left the area and then released. These birds had to select their migratory route on the basis of the inherited directional information they possessed, without any chance of being guided by their experienced conspecifics. In the second series of experiments, several groups of juveniles were displaced from the Kaliningrad Region to the Volga area and to Western Siberia. Both areas lie outside the breeding range of the white stork so the displaced birds also had to rely on their innate migratory program. Results from the differently designed experiments did not match. Nor did they match with the results of earlier experiments on the delayed departure of juvenile white storks as reported by several authors. We suggest that naïve white storks (and maybe other soaring migrants) rely on social interactions when selecting their autumn migratory route to a much greater extent than do passerine long-distance migrants.