Montagu's Harriers breed from western Europe and northwest Africa across to Mongolia. They winter in sub-Saharan Africa, parts of Arabia and India. In Europe, their biggest numbers are in Iberia, France and Russia.
    In the 19th century they bred regularly in parts of southern and eastern England but their numbers fell from the end of the century and up to the 1914-18 War. Thereafter they increased again to 15-25 pairs annually by the 1930s, scattered across East Anglia, southern England and south Wales. After the 1939-45 War their numbers continued to increase. The 1968-72 Breeding Atlas estimated at least 40-50 pairs, possibly up to 70-80 pairs. At this time they were recorded from as far north as north Wales, northeast England and even Scotland. From the late 1950s onwards however their numbers began to decline, possibly because of drought in their wintering areas in the Sahel, but also because of the activities of egg-collectors and illegal persecution by shooting interests.
    In Wiltshire there were regular records of small numbers breeding in the 19th and first half of the 20th centuries but such records had become rare after the mid-1950s. Between 1954 and 2000 there were records of breeding attempts in seven years, usually by just one pair except in 2000 when three pairs nested, though only one was successful. There were records of other non-breeding individuals present during most years of the 1990s. Since 2000 young have been successfully raised in every year except 2001 and 2003, with up to four pairs raising totals of up to 13 young per year and up to 14 non-breeding birds also present. These recent successes have been made possible by determined efforts to protect nest sites from predators and from illegal activities by egg collectors and others.

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.