Hoe zilvermeeuwen Amerikaanse zwaardscheden (Ensis Directus) vangen

This note reports how Herring gulls catch American razorclams Ensis directus in the Dutch Wadden Sea. Herring gulls had no problem in collecting Ensis directus during low tide on the lower tidal flats near Texel. They collected Ensis directus specimens protruding half out of the sediment and unable to reburrow. It is suggested that this curious behaviour of razor-clams might be due to the parasitic trematodes found in the foot of these Ensis. They might force the clams out of the sediment to be an easier prey for birds, probably the final host of this trematode. During high tide hundreds of eider were feeding on Ensis on the same tidal flat. Herring gulls were observed to steal Ensis directus from eider, this kleptoparasitism proved to be a successful alternative method for Herring gulls to catch Ensis.