Complex Timing of Marsh Harrier Circus aeruginosus Migration Due to Pre- and Post-Migratory Movements

摘要: We tracked three juvenile and 14 adult Marsh Harriers Circus aeruginosus from southern Sweden via satellite to investigate migration strategies. Four individuals were for at least two years. All juveniles four of the adults made west-oriented pre-migratory movements well before onset autumn migration, trans-Saharan migrants visited post-migratory stopover areas in tropical Africa. By these movements, harriers presumably exploit short-term regional variation food abundance. Autumn spring occurred a relatively narrow corridor, without distinct differences between sexes timing, speed, distance, duration except that females tended migrate faster than did males. Juveniles migrated shorter distances adults, speeds lower. Spring was similar terms speed duration. not cross Sahara Desert birds, one female juveniles, wintered Europe, which is accordance with recent increase number (juvenile) wintering northwestern Europe. birds crossed West showed site fidelity breeding, areas. The overall Ospreys Pandion haliaetus Honey Buzzards Pernis apivorus, other migrants. use fly-and-forage promote resulting whereas are particularly apt thermal soaring. How balance foraging versus travelling accomplish their rapid remains be resolved.