Differential wintering area selection in Eurasian Marsh Harrier (<i>Circus aeruginosus</i>): a ringing recoveries analysis

Abstract

Capsule The Eurasian Marsh Harrier shows a leapfrog migration pattern with individuals breeding in Northern and Eastern Europe wintering further from their breeding grounds than individuals belonging to the populations of Western and Southern Europe. Aims We analyse wintering distribution of Marsh Harriers in relation to their breeding grounds to identify differential wintering area selection strategies. Methods We used ring recovery data of 320 individuals from the European population. Latitude and longitude of ringing sites as well as age-class were used to explain variation in the distances between breeding areas and wintering sites. Moreover, we analyse differences in migration distances performed by males and females and differences among individuals wintering in sub-Saharan Africa. Results Distance covered to reach the wintering ground increases with increasing latitude and longitude of the breeding sites. Marsh Harriers breeding in Northern and Eastern Europe migrate farther than individuals belonging to the populations within Western and Southern Europe, with no effect of age-classes in relation to the latitude of wintering. Males show a tendency to migrate longer distances than females. Finally, when taking into account only birds wintering south of the Sahara desert, juveniles winter further west than adults. Conclusions The results are consistent with the assumption that this species shows a leapfrog migration. We suggest that the difference in the longitudinal distribution of juveniles and adults wintering south of Sahara could be related to the different ability of experienced individuals to compensate for the wind drift of dominant easterly winds during migration over the desert in autumn.