Lesser Black-backed Gull © Mike Atkinson
Lesser Black-backed Gulls normally breed near the coast, nesting on flat ground amongst grasses. Ground predators, including foxes and mink, are their main enemies, and this adaptable species has recently realised that the roofs of buildings provide a safe alternative. The habit of rooftop nesting has spread rapidly in Britain, from 325 nests at 11 colonies in 1976, to 2,501 nests at 63 colonies in 1993-95 and 10,790 nests at 125 colonies in 1999-2002 (Mitchell et al 2004). About 10% of the country’s Lesser Black-backed Gulls now breed on rooftops.
In Cheshire, a pair of Lesser Black-backed Gulls nested at Witton flashes (Northwich) in 1943, with three pairs reported nesting on Burton Marsh in 1955 and 1956, and a single pair there in 1978 (First Atlas). The annual county bird reports show that a pair held territory, displayed and copulated without nesting, at Inner Marsh Farm (SJ37B) every year from 1996 to 2000, being responsible for substantial predation of eggs and chicks of Black-headed Gulls, Coots and ducks. A pair also held territory at Woolston (SJ68U) in 2000. The year 2003 saw the first nesting in Cheshire and Wirral for a quarter-century, and the start of a significant new development, when a pair raised chicks on the roof of a dockside building in Birkenhead (SJ29V). The same site was used again in 2004, Mike Gough reporting the female sitting tight on the nest in poor weather on 20 June, with the male nearby. During this Atlas period pairs were seen on rooftops elsewhere in Poulton, Birkenhead (SJ39A) and New Brighton (SJ39C), with a single bird possibly breeding in a different area of Birkenhead (SJ38J). Much farther inland, in 2006 in an industrial estate at Landican (SJ28X) Steve Holmes saw recently fledged young and adults behaving in a very aggressive manner to anyone in the vicinity.
Lesser Black-backed Gulls also breed just outside the county boundary on the roof of the Ford/ Jaguar building at Halewood (SJ48L); in 2005, there were forty or more pairs (White et al 2008).
The species was recorded during this survey from many other tetrads with no suitable breeding habitat. It is the dominant species on the county’s landfill sites in midsummer, with ringing showing that many of the adult birds are commuting daily from breeding grounds on the Ribble saltmarshes, Lancashire and Walney Island on the Cumbrian coast. There are also many immature birds around: they do not breed until at least four years of age.
Now that some birds have taken to breeding on buildings, there is no shortage of nest-sites for them, and an abundance of food, either fish or other marine items, putrefying waste at landfill sites or, increasingly, take-away food discarded by humans in urban areas. In view of the rapid development of rooftop breeding in other urban coastal areas it would be good to monitor thoroughly the progress of this habit in Cheshire and Wirral.
Sponsored by Dave Murray
