The Yellow-legged Gull, long regarded as a southern European race of the Herring Gull, was only formally recognised as a separate species in 2005. They breed from the Atlantic islands and northwest Africa, across the Mediterranean to Cyprus and on Black Sea coasts from Rumania to Turkey. In the 1970s they spread north to nest along the Atlantic coast of France and up the Rhone valley. They first appeared as non-breeding visitors in southern Britain in the late 1970s though it was not until 1997 that they were first recorded breeding, at a site in Dorset. Bird Atlas 2007-11 recorded just that one confirmed breeding record though there were records of probable breeding from two other sites in southern England and indications of possible breeding activity in three further squares. Non-breeding birds were recorded in summer in 307 squares in England and there were a similar number of records in winter with the addition of a scattering of records in Scotland.
    The first record of a Yellow-legged Gull in Wiltshire was at Swindon rubbish tip in December 1985. Next came records from three sites in January 1987 and from then on there have been records in every winter. From 1995 onwards they began to be seen in late summer then in 1998 and 1999 in every month. Birds of Wiltshire recorded them at 17 sites in winter (though only three sites feature on the winter distribution map), and in at least one site in summer (though again this did not appear on the breeding season distribution map). WTA2 also recorded them at 17 sites in winter, and two in summer.

 

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.