HIGH PROFIT AT HIGH-RISK FOR JUVENILE DUNLINS CALIDRIS-ALPINA STOPPING OVER AT HELGOLAND (GERMAN BIGHT)

During autumn migration, up to 1100 juvenile Dunlins Calidris alpina p er day forage on the island of Helgoland (SE North Sea). Beds of washe d up wracks and kelp sire used as a feeding habitat where they take ke lp fly larvae (Coelopidae) at a high rate (17.8 larvae min(-1)). This high energy intake allows rapid fattening (1.7-3.3 g day(-1)) and shor t lengths of stay (about 4-5 days), leading to a high daily turnover o f individuals (0.2-0.7 day(-1)). Despite the good conditions for meeti ng energetic requirements, staging at the island incurred a high depre dation risk from migrating birds of prey. Different feeding priorities might be one reason why most adult Dunlins avoid Helgoland as a stagi ng site and instead aggregate at large staging areas such as the Wadde n Sea, where individual depreciation risk is more than 50 times less.