The Black-headed Gull (Chroicocephalus ridibundus) is a small gull which breeds in much of Europe and Asia, and also in coastal eastern Canada. Most of the population is migratory, wintering further south, but some birds in the milder westernmost areas of Europe are resident. This gull is 38-44 cm (15-17½ in) long with a 94-105 cm (37-41 in) wingspan. It breeds in colonies in large reedbeds or marshes, or on islands in lakes, nesting on the ground. Like most gulls, it is highly gregarious in winter, both when feeding or in evening roosts. It is a bold and opportunist feeder and will scavenge in towns or take invertebrates in ploughed fields with equal relish. Reference: Wikipedia