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.


Relative to average

Nos tetrads

More abundant



Equally abundant



Less abundant



Not surveyed in both periods

Willow Wablers breed patchily in northern Spain and from Ireland, Britain and central France eastwards across temperate and boreal Eurasia and Siberia in a narrowing band almost to the Bering Sea. In winter all Willow Warblers migrate to Africa south of the Sahara.
    In Britain they are the most numerous summer visitor, distributed widely from the English Channel coast to the Outer Hebrides and Shetland. Bird Atlas 2007-2011 showed little change in population distribution since the 1968-72 Breeding Atlas - an increase in the number of occupied 10km squares in the northern and western isles of Scotland, partly offset by a few reductions round the English coast, producing a 3% increase overall. Population abundance figures on the other hand showed a very marked northward shift: BBS results from 1995 to 2010 revealed a 33% increase in numbers in Scotland and a 28% decline in England.
    In the 19th century, and most of the 20th, Willow Warbler was regarded as the most numerous of the Phyllloscopus warblers breeding in Wiltshire but by the beginning of the 21st century it had fallen marginally behind Chiffchaff. Tetrad counts for WTA2 also clearly showed the thinning out of numbers resulting from the general northwards shift referred to above: whereas Birds of Wiltshire recorded Willow Warblers in 789 tetrads, with breeding in 468 of them, WTA2 found them present in only 622 tetrads, with breeding in 221.

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.