Gull breeding habitats and nest sites
Gulls are semi-colonial nesters and, in some instances, form colonies of thousands of birds, especially kittiwakes.
Nest sites for gulls
Traditional nest sites include sea-cliffs, sand dunes, islands on the coast and inland and other inaccessible locations. Some lesser black-backed and herring gulls have successfully adopted roofs for nesting.
The nest is a well-constructed cup made of twigs and grasses. The clutch of two to four eggs is incubated by both sexes for up to 30 days in May and June. The chicks hatch fully covered in down and are fed by both parents. With the exception of the kittiwake, the chicks leave the nest and move to the relative safety of nearby vegetation when only a few days old. The parents look after them until they fledge after five or six weeks and for a period afterwards.
Gulls are long-lived birds - the larger species only start to breed when four years old and some can live to their upper twenties.
Why are some gulls nesting in urban areas?
- Gulls are found mainly on the coast in summer, although black-headed gulls also nest inland. Large numbers of some gull species move inland in winter, roosting on lakes and reservoirs and feeding on farm fields and refuse tips.
- Kittiwakes feed on small surface-shoaling fish and crustaceans caught offshore, and will also scavenge at fishing vessels. They do not forage inland. Large gulls (herring, lesser black-backed and great black-backed) feed on almost anything of suitable size.
- Herring gulls generally forage within 10km of their nests while lesser black-backed gulls will travel much further to feed. They hunt fish and other sea creatures, but also take carrion, rubbish, litter and waste food, as well as eggs and chicks of other seabirds. They are natural scavengers and take advantage of organic waste at landfill sites and in towns.
- All gulls, except kittiwakes, will feed on ploughed fields. Herring and black-headed gulls in particular can be found ‘charming worms’ on pastures, playing fields and other grassy areas.
The kittiwake, with more than a third of a million pairs is the most numerous of all the UK gull species. Herring, lesser black-backed and black-headed gulls each have in excess of 100,000 breeding pairs, while the others have significantly smaller populations.
All seven breeding gull species are birds of conservation concern. The herring gull is now red listed due to the severe declines in its national breeding population. The other species are amber listed for differing reasons. The Mediterranean gull is the only species whose numbers are currently not declining.
Why are gulls declining?
Kittiwake numbers are declining primarily because of shortage of their preferred prey of sandeels. It is thought that this is being driven by climate change.
The cause of the declines in other species is not yet known, but could be the result of changes in their maritime environment, including pollution or changes in commercial fishing practices. Research is urgently needed to establish the causes of these declines so that measures to reverse them can be set out.