Paalzittende Zeearenden Haliaeetus albicilla op de Hellegatsplaten

Wintering White-tailed Eagles have increased in numbers in recent decades, also in the delta of the southwestern Netherlands. The closure of creeks with dams in the 20th century resulted in the salt water turning fresh. In winter 2009/10 numbers of White-tailed Eagles were higher than ever before, with the first – immature – bird arriving on 11 August. The birds showed a clear preference for Hellegatsplaten and its surroundings, where ducks and geese abounded. Nuumbers steadily increased to 8 in 2015/16. These birds were often seen resting on electricity pylons, from where they attacked ducklings of Tadorna tadorna, Branta leucopsis and B. canadensis (June), later on mostly young of Fulica atra and ducks, and moulting B. leucopsis. The pylons were also used for nocturnal roosting (local trees are still few and far between, and relatively young, i.e. <45 years old). Interestingly, where eagles were most frequently observed, numbers of geese substantially dropped. Moreover, the nearby former tidal creeks were avoided by foraging Platalea leucorodia when many White-tailed Seaeagles were around. Apparently, a redistribution of potential prey species is taking place in the near-permanent presence of White-tailed Eagles.