High numbers of Lesser Black-backed Gulls Larus fuscus foraging at trawlers and in natural feeding flocks in the Southeastern North Sea

Up to an unprecedented 3800 Lesser Black-backed Gulls were seen foraging behind Dutch beam trawlers 35-80 km north off the Wadden Sea islands, 30 June-4 July 1997. Gulls leaving the trawlers had visibly filled gullets (pharynx) and were obviously carrying food to the colony. The observations confirm the significance of discards in the diet of Lesser Black-backed Gulls during chick-rearing. However, during other cruises in June and July 1997 in the German Bight, large flocks of ‘naturally feeding’ gulls were encountered. The largest flock comprised 1100 Lesser Black-backed Gulls, 560 Herring Gulls and 1000 Kittiwakes. These flocks were found in waters of 10-20 m depth and 6-30 km off the nearest colonies, in an area without fishing fleets. Earlier studies in colonies have indicated the significance of natural prey (non-discards), but reported sightings at sea of large flocks of naturally feeding’ gulls are still quite rare.