SEEN - SE European Bird Migration Network
Nocturnal bird migration in the Balkan Area: spatial and temporal distribution of passerine migrants
Pavel Zehtindjiev(1), Felix Liechti(2)
1) Institute of Zoology, Bulgarian Academy of Sciences, Bulgaria
2) Swiss Ornithological Institute, Switzerland

The spatial and temporal distribution of nocturnal migration in the Balkan Region was studied during the spring and autumn of 2000-2002. The East-European Flyway was not covered by direct registrations of the night migration until now. By means of moon watching technique, the nocturnal passage was recorded simultaneously at 39 sites in Bulgaria, SE Romania, northern Greece and Black Sea coast of Turkey. The composition of species was registered in the course of the observations at stopover site in NE Bulgaria. Orientation behaviour of most numerous species has been tested in orientation cages.
Mean migratory traffic was 1600 birds*km-1h-1 in autumn and 900 birds*km-1h-1 in spring. The migration intensity was similar between E – W and N – S gradient. Slight shift from SSW to S during the autumn and from NNE to N during the spring coincides with the change of trans-Saharan and short distance migrants. The scatter of directions decreases in the course of migration. Flight directions were virtually opposite between seasons, but the prevalence of south directions in autumn changes to NE in spring. On a large-scale view, an interaction between topography, winds and innate directions of migrants was revealed in the pattern of seasonal migration of Balkan region. The results indicate that a substantial proportion of nocturnal migrants along the eastern flyway crosses the sea on a broad front and do not need to adjust their innate migratory direction to reach their winter quarters in Africa.
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