The Mediterranean Gull - , Ichthyaetus melanocephalus - breeds almost entirely in Europe.  There are colonies elsewhere in southern Europe, and this species has undergone a dramatic range expansion in recent decades.

It has colonised Britain, mainly in southern and eastern England with more than 90 pairs in 2000. This gull breeds in colonies in large reedbeds or marshes, or on islands in lakes; where its population is small, it nests in Black-headed Gull colonies. Like most gulls, it is highly gregarious in winter, both when feeding or in evening roosts. It is not a pelagic species, and is rarely seen at sea far from coasts.

Mediterranean gulls are increasingly choosing the Medway Estuary as a place to breed the according to the RSPB. Recent surveys of the estuary counted more than 200 breeding pairs of this protected bird, more than a third of the UK breeding population. The greatest concentrations were found on the RSPB reserve at Nor Marsh.