Barn Swallows breed throughout the Northern Hemisphere. Most of the European breeders winter in sub-Saharan Africa, though a few go no farther than North Africa or southern Spain. The British population are among the farthest travellers, wintering in Namibia and South Africa.

Bird Atlas 2007-2011 recorded Barn Swallows breeding in 95% of 10km squares in Britain, which represents an increase of 3% since the 1968-72 Breeding Atlas. The only gaps were in central London and in a few areas in northern Scotland. But while overall distribution thus changed only marginally, relative abundance records showed a steady increase in numbers in north Britain and a decrease in southeast England. The species has always been among the latest summer migrants to depart, often not until well into November, and there have recently even been some attempts to overwinter.

Historical records in Wiltshire give few precise figures but suggest fluctuating numbers probably as a result of varying conditions on the migration routes. Recent records show a general pattern in line with the national figures: Birds of Wiltshire recorded Barn Swallows present in 859 tetrads (94%), with breeding in 612; WTA2 found them in more tetrads (888 = 97%) but with breeding in fewer (574).

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: 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.