The British Pied Wagtail, Motacilla alba yarrellii is one of about 12 sub-species of the White Wagtail Motacilla alba alba. The nominate race also occurs in Britain, as a passage migrant and as a rare breeder, while M. a. yarrellii is also found in coastal areas of northern France, Belgium, the Netherlands and Denmark. Other races are found within an area stretching from Greenland, Iceland and western Europe right across Eurasia to western Alaska and south to Morocco, Asia Minor, Iran, the Himalayas and the Indo-Chinese countries. North, central and east European White Wagtails are migratory, moving south in winter, some to within the range of the southernmost breeders, others to northern and sub-Saharan Africa and southern Asia.
    In Britain Pied Wagtails are found almost everywhere in summer, most abundantly in Wales, northern England and eastern Scotland. In winter many of those in the northern areas move south, to southern Britain and beyond as far as Iberia. This leaves them absent from upland areas of Scotland and northern England.
    In Wiltshire they have been recorded as very common at least since the mid-19th century, being absent in summer only from a few exposed areas where there are no suitable structures to provide nesting sites. In winter, numbers are swollen by migrants from further north. They gather at night into roostsof 100+ individuals. Birds of Wiltshire recorded them in 683 tetrads with breeding in 373, WTA2 recorded them in 601 tetrads with breeding in 290.

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.