Kauwtjes Corvus monedula als prooi van Zilvermeeuwen Larus argentatus en Kleine Mantelmeeuwen L. fuscus

In summer 2009, fresh but partly eaten remains of Jackdaws Corvus monedula were regularly found within the Kelderhuispolder colony of Herring Gulls and Lesser Black-backed Gulls. Small chicks were offered Jackdaw pulli, but most of the remains indicated that adult, or at least free-flying Jackdaws were taken. Observations next to the ferry at Texel confirmed that Herring Gulls were actively hunting adult Jackdaws and tried to bring them down into the sea to drown them. Three further reports of Herring Gulls killing apparently healthy adult Jackdaws were received. It was the first time in four years of study that Jackdaws were frequently delivered as prey items and we estimate that at least hundreds of Jackdaws were killed and transported into the gull colonies in the south of Texel in 2009.