Map explanation

This map shows where changes occurred in the breeding season distribution 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.

Gains and improvements


Nos tetrads

Absent to present



Present to breeding



Absent to breeding



No change


Nos tetrads

Present in both



Breeding in both



Losses and declines


Nos tetrads

Present to absent



Breeding to present



Breeding to absent



Sedge Warblers breed throughout Europe except in the Mediterranean region, including northern Fenno-Scandia and North Russia, then extending to western Siberia, parts of the Balkans and Asia Minor. They winter in sub-Saharan Africa, from Senegal to Ethiopia then south to South Africa.
    They were widespread and common in Britain in the 19th century, and there was little change in their status in the first two-thirds of the 20th. From the late 1960s however there have been marked fluctuations linked to conditions in the Sahel. A severe drought there in winter 1983/84 led to high mortality such that fewer than 5% of adults returned to their breeding sites in Britain the following summer. Numbers continued low into the 1990s. There was a 12% contraction in breeding range between the 1968-72 Breeding Atlas and the 1988-91 Breeding Atlas , but this was then followed by a 17% increase between 1991 and Bird Atlas 2007-2011 giving a net increase of 3% over the period as a whole.
    In Wiltshire, numbers remained roughly stable throughout the last third of the 20th century but thinned out a bit during the first decade of the 21st century. Birds of Wiltshire recorded them in 190 tetrads, with breeding in 120. Bird Atlas 2007-2011 found them in 187 tetrads with breeding in 106.

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: The Breeding and Wintering Birds of Britain and Ireland. BTO Books. 
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.