Hen Harriers breed in open country right across Eurasia from Ireland to Kamchatca.Those that nest north of the Baltic migrate south in winter, a few reaching as far south as North Africa.
    Until the early 19th century they used to breed in suitable lowland areas throughout Great Britain but intense persecution led to their becoming extinct by 1900 everywhere except  some parts of Orkney and the outer Hebrides. Pairs first returned to mainland Scotland in 1939 and the reduction of persecution during the 1939-45 War enabled them to regain a toehold so that by the 1970s they had recolonised Scotland, northern England and north Wales. Bird Atlas 2007-11 recorded a 29% growth in the summer range in Britain since the 1968-72 Breeding Atlas mostly by expansion within the existing breeding areas in the north. In winter there was a 24% increase in distribution since the 1981-84 Winter Atlas.
    In Wiltshire Hen Harriers occur mostly as winter visitors though there are occasional records of them in the breeding season, with nesting reported in the early 19th century and in 1936 and 2003. In 2019 Natural England launched a scheme to re-introduce Hen Harriers in southern England by releasing birds sourced in southern Europe at a site close to Salisbury Plain.

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.