The distribution and abundance of Larus gulls nesting on buildings in Britain and Ireland

Abstract

Listen

Translate article

During the breeding season of 1994, a survey of Larus gulls nesting on buildings and other man-made structures in Britain and Ireland was carried out to determine their distribution and abundance, and to assess the changes that had occurred since the last survey in 1976. The two main species involved were Herring and Lesser Black-backed Gulls, with records received of 11 047 pairs and 2544 pairs, respectively. Estimated numbers may be as high as 16 900 pairs of Herring Gulls and 3200 pairs of Lesser Black-backed Gulls, constituting 8.2% and 3.6%, respectively, of the total breeding populations of these species in Britain and Ireland. Since 1976, gulls nesting on buildings have continued to increase, both in terms of the number of breeding pairs (Herring Gulls by 10% per annum; Lesser Black-backed Gulls by 17% per annum) and the number of sites colonized (Herring Gulls by 5% per annum; Lesser Black-backed Gulls by 13% per annum). This increase has been greatest in the Lesser Black-backed Gull, but that of the Herring Gull is of particular interest as its numbers in Britain and Ireland have declined during this period. Records were received of 236 pairs of Common Gulls and 11 pairs of Great Black-backed Gulls nesting on buildings. In most areas, coastal towns have now been colonized by roof-nesting gulls and sites further inland are being colonized, especially by Lesser Black-backed Gulls. There has been an increased colonization of industrial sites in towns since 1976 and this has led to the formation of much denser colonies than previously found in urban areas. Small colonies of Herring Gulls nesting on rooftops increase in size at a higher rate than large colonies, although the actual numerical increase is still greater in larger colonies. There is no evidence of established colonies of roof-nesting gulls disappearing naturally and the rapid increase in size of small colonies means that they become established very quickly, often before they are perceived as a problem. Considerable effort has been put into attempting to reduce the numbers of gulls nesting in some towns. As yet, however, no successful management methods have been developed.