Barn Owls, the only representative of the Tytonidae family found in Europe, are the most cosmopolitan of all owls, being found in most of the Americas north to southern Canada, in western and central Europe, in much of Africa, patchily in southern Asia from Turkey to Vietnam and Malaysia, down to Australia and on many islands of the Caribbean, Atlantic, Mediterranean, Indian Ocean and southwest Pacific. There are over 30 sub-species; the one found in western Europe is the nominate race Tyto a. alba.
    Barn Owls' plumage has evolved to make them silent in flight but this has also had the effect of reducing their natural insulation and they are not well adapted to prolonged periods of severe weather. This explains their absence from more northerly latitudes; in Britain few of them nest north of central Scotland or in the uplands of northern England and Wales.
    In the first half of the 19th century Barn Owls were regarded as common in Britain but by the end of the century numbers were reported to be declining, a trend that continued well into the 20th century. A decrease of 37% was recorded in population distribution between the 1968-72 Breeding Atlas and the  1988-91 Breeding Atlas. Possible causes included habitat loss, pesticide poisoning loss of suitable nesting sites and a reduction in the availability of small rodents as a result of improved farming techniques. By the end of the century though numbers had stabilised, largely because of the widespread deployment of nest boxes - in 2000 it was estimated that  between 75 and 80% of known Barn Owls in the UK were nesting in boxes. In Wiltshire, where there are a number of active next-box schemes, numbers are increasing: Birds of Wiltshire recorded Barn Owls in summer in 254 tetrads, with breeding confirmed or probable in 182 of them; WTA2 reported them in 318 tetrads with breeding in 249.


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.