Numbers, distribution and population trends of large gulls breeding in Cumbria, northwest England

Abstract

This paper reports the results of a survey of large gulls breeding in Cumbria in 2009, together with an assessment of recent population trends. The survey found totals of 15,489 apparently occupied nests (AON) in 43 colonies for Lesser Black-backed Gulls Larus fuscus, 4,747 AON in 40 colonies for Herring Gulls L. argentatus and 85 AON in seven colonies for Great Black-backed Gulls L. marinus. A substantial part of the populations for all three species was concentrated in a few large coastal colonies, but there were many smaller colonies, mostly of roof-nesting birds in coastal towns, as well as a number of generally small colonies inland, chiefly in quarries or on islands in lakes. Since the 1998–2002 Seabird 2000 census, coastal colonies for all three species have shown a marked reduction in breeding numbers, but increases at those in urban areas; the declines far outweighed the increases, however. Despite the overall downward trend in the breeding population in this period the number of colonies increased. The factors responsible for these changes include the food supply, disturbance by man, and, to a lesser extent, disease.