Ragworms and other marine food items in the diet of Herring Gulls Larus argentatus breeding on Lady Isle, Firth of Clyde, Scotland

The diet of Herring Gulls Larus argentatus breeding in southwest Scotland in 2018 and 2019 was investigated by analysis of regurgitated pellets. Marine food items were found in 24.2% of 314 pellets, with the major items being Norway Lobster Nephrops norvegicus (9.6% of pellets), fish (8.9%), ragworms Eunereis longissima (8.0%) and crabs (3.5%). This is the first report of the detection of the ragworm Eunereis longissima in pellets produced by gulls in the British Isles but their availability to gulls is likely to be seasonal, and their contribution to the diet is unlikely to be high unless consumed in large numbers. Although fish significantly contributed to the energy needs of the gulls, Norway Lobsters did not. A change in commercial fishing from targeting demersal fish to Norway Lobsters could, therefore, reduce the nutritional quality of food available to Herring Gulls.