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

4

<1%


Equally abundant

0

0%


Less abundant

0

0%



Not surveyed in both periods

Dippers are found from northwest Africa and western Europe, across central Asia to central China. They are specialist feeders mostly on aquatic invertebrates which they catch by diving and swimming underwater in fast flowing streams or rivers with weirs.
    In Britain they are most numerous in Scotland, Wales and in northern and southwest England, and are absent from lowland areas in central, southern and eastern England. They are sedentary and consequently there is little difference between their summer and winter distribution maps, though their numbers have been thinning out. Annual monitoring data revealed a 30% population decline between 1970 and 2010, believed to be the result of acidification of streams by run-off from conifer plantations leading to a reduction in the invertebtate populations.
    In Wiltshire Dippers were first recorded in the 1880s and from then until the mid 1940s they gradually expanded their range, mostly along tributaries of the Bristol Avon and the Salisbury Avon. Since 1950 they have been in decline, in line with the national trend. Birds of Wiltshire recorded them in 18 tetrads, with breeding in 15 of them along two tributaries of the Bristol Avon (the River Frome and the By Brook). WTA2 found them in 12 tetrads with breeding confirmed only at five separate sites on the By Brook . There was also evidence of probable breeding at one of three locations on the River Nadder.

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: 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.