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Map explanation

This map shows where changes occurred in the relative abundance of the species in Wiltshire between 1995-2000 and 2007-2012, as revealed by the fieldwork for Birds of Wiltshire (Wiltshire Ornithological Society 2007) and the shared fieldwork for Bird Atlas 2007-2011 (BTO 2013) and for Wiltshire Tetrad Atlas 2007-2012.

Key

Relative to average

Nos tetrads


More abundant

265

29%


Equally abundant

0

0%


Less abundant

0

0%



Not surveyed in both periods

Lesser Black-backed Gulls breed from Iceland and western Iberia eastward to Siberia. Of the 200,000 -230,000 pairs estimated to be breeding in Europe west of Russia in 1997, around half were nesting in Great Britain. Until the mid 20th century the British breeding population was regarded as essentially migratory, with all but a few moving south to winter in southern Europe and north Africa. From the 1950s onward however increasing numbers, particularly of second winter and older birds, have remained to over-winter in Britain where they have been joined by birds from the expanding breeding populations in Iceland, the Faeroes and northwest Europe.
    Bird Atlas 2007-11 recorded remarkable expansions of their distribution ranges in the British Isles in both winter (up 27% since the 1981-84 Winter Atlas ) and summer (up 52% since the 1968-72 Breeding Atlas ). Much of the expansion has consisted of increases in the numbers breeding inland, mostly on man-made structures.
    In Wiltshire before 1948 there were only scattered records of Lesser Black-backed Gulls on passage in spring and autumn but from then on they began to be seen more regularly, mostly on passage but also increasingly in winter. The first record of their breeding in the county came in 1984 when a pair nested on a factory roof in Trowbridge. Since then they have been recorded nesting on roofs in an increasing number of towns, mostly along the Bristol Avon, but also in and around Swindon. Birds of Wiltshire recorded probable or confirmed breeding in nine tetrads; WTA2 recorded breeding in 23 tetrads. Winter records increased from 32% of tetrads surveyed in Birds of Wiltshire to 47% in WTA2.References
The following references are used throughout these species accounts, in the abbreviated form given in quotation marks:

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.

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