Common Terns breed in much of Eurasia and North America, with isolated populations also on some north Atlantic islands and in the Caribbean and West Africa. They winter along coasts south of their breeding range.
    In Britain a reduction in the the summer distribution range between the 1968-72 Breeding Atlas and Bird Atlas 2007-11 in Scotland (where they nest mostly along the coasts) was more than offset by a substantial increase in southern and eastern England, particularly at inland sites, resulting in a 13% increase overall. Those nesting in Great Britain winter mainly along the coast of the Gulf of Guinea.
    In Wiltshire they were regularly recorded in small numbers as passage migrants from the 19th century onwards but it was not until 1979 that the first successful nesting attempt was confirmed, at the Cotswold Water Park (CWP). They bred there also in 1980, but thereafter not again until 1988 (though by now they were breeding regularly in the Gloucestershire part of the CWP). There were further attempts in 1993 and 1994 (at least one of which managed to fledge a single young) but it was not until 1996 that regular breeding started, using a raft that had been floated the previous year in CWP lake74. A second raft was moored alongside the first one in 1997 and five pairs bred successfully. Since then they have bred there every year, sharing the rafts with Black-headed Gulls. Breeding has also been recorded elsewhere in the CWP, and at Coate Water, other Swindon sites, Langford Lakes and Wilton Water. WTA2 recorded them breeding in 18 tetrads, a marked expansion from the seven tetrads in Birds of Wiltshire.

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.