Ospreys breed or winter on every continent except Antarctica. Those that nest in Europe migrate in winter to Africa, south of the Sahara but north of the equator. Persecution by fishing interests and collectors almost eradicated them from western and central Europe by the early years of the 20th century, leaving them breeding only on Corsica and the Balearic Islands, in Fenno-Scandia and the eastern half of the continent.
    In Britain, a once common Scottish population was reduced to just a few pairs by the end of the 19th century and died out altogether after 1916 when the last known nest was abandoned at Loch an Eilean. Migrating Ospreys from Fenno-Scandia did however continue to pass through Britain and in the mid 1950s they began to re-colonise Scotland. Predations by egg-collectors and disturbance by over-enthusiastic birdwatchers foiled their initial nesting attempts. But they persevered; seven breeding pairs were recorded in the 1968-72 Breeding Atlas. This increased to 73 pairs by 1991 and at least 211 pairs by 2010. The original Scottish population expanded over the border to Cumbria in 2001 and Northumberland in 2010 while a translocation programme launched in 1996 using Scottish birds succeeded in establishing a breeding population at Rutland Water by 2001. Birds from this programme also successfully bred at two sites in north and central Wales, in 2004 and 2011 respectively.
    In Wiltshire passing migrant Ospreys were regularly shot throughout the 19th century until they ceased appearing in 1883, after which there were no more records until one was seen in 1951. There were nine further records in the next 22 years, until by 1974 they were appearing annually, in increasing numbers as birds from the expanding Scottish population passed through on their way to and from their winter quarters in Africa. Birds of Wiltshire recorded their numbers in five-year periods from 1971-75, when there were five records, to 1996-2000, when there were 27 (the highest total was 40 in 1991-95). Annual totals recorded in Hobby between 2001 and 2017 varied from two in 2003 to 29 in 2012. Singletons have remained in Wiltshire throughout the summer in at least four years, though there have been no attempts to breed.

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.