Common Gulls breed right across northern Eurasia and in Alaska and northwest Canada. The British breeding population, mostly in Scotland but with a scattering as far south as Kent and Hampshire, represents about 10% of the total European population, excluding Russia. In winter those from the most northern areas of their breeding range move south, to the North Sea and Atlantic coasts, to the inland seas and along major rivers. In Denmark, northern France, Britain and Ireland they also winter inland in substantial numbers.
    In Wiltshire in the 19th century Common Gulls were the commonest gull species in winter. They maintained their numbers in the 20th century (while other gull species increased their numbers), with flocks of several hundreds and even up to 1000, particularly in the western half of the county. Between Birds of Wiltshire and WTA2 they expanded their range from 19% of all surveyed tetrads to 33%.
    They have been reported in every month though there have been no records of breeding attempts.

 

References
The following references are used throughout these species accounts, in the abbreviated form given in quotation marks:
1968-72 Breeding Atlas” – Sharrack, J.T.R. 1976:  The Atlas of Breeding Birds in Britain and Ireland. T. & A. Poyser
1981-84 Winter Atlas” – Lack, P.C. 1986:  The Atlas of Wintering Birds in Britain and Ireland. T. & A. Poyser
1988-91 Breeding Atlas” – Gibbons, D.W., Reid, J.B. & Chapman, R.A. 1993: The New Atlas of Breeding Birds in Britain and Ireland 1988-91. T. & A. Poyser
Birds of Wiltshire” – Ferguson-Lees, I.J. et al. 2007 : Birds of Wiltshire, published by the tetrad atlas group of the Wiltshire Ornithological Society after mapping fieldwork 1995-2000. Wiltshire Ornithological Society.
Bird Atlas 2007-2011” – Balmer, D.E., Gillings, S., Caffrey, B.J., Swann, R.L., Downie, I.S. and Fuller, R.J. 2013: Bird Atlas 2007-2011: the Breeding and Wintering Birds of Britain and Ireland
WTA2” – ("Wiltshire Tetrad Atlas 2 ") the present electronic publication, bringing together the Wiltshire data from “Birds of Wiltshire” and “Bird Atlas 2007-11”, together with data from further fieldwork carried out in 2011 and 2012.
"Hobby" - the annual bird report of the Wiltshire Ornithological Society.