Cormorants were traditionally regarded as seabirds but have become increasingly familiar in winter in inland waters. They breed across Eurasia from Iceland to Japan. In northwest Europe they nest mainly in colonies along rocky coasts, including in Great Britain, though in recent years there has been a significant increase in inland breeding, especially in southeast England.
    In Wiltshire Cormorants were heavily persecuted in the 19th and 20th centuries because of their perceived threat to fisheries, persecution that partly continued, illegally, even after the introduction of protection in the 1980s. Despite this, numbers wintering in the county increased steadily in line with the marked national spread into inland waters: the 1981-84 Winter Atlas recorded the species in only nine 10km Wiltshire squares. Birds of Wiltshire found them in 18; WTA2 recorded them on all the significant rivers and lakes, in a total of 32 core 10km squares.
    In the breeding season the species was regarded as only an occasional visitor to the county until the latter part of the 20th century when they began to be recorded regularly in small numbers during the summer. The first breeding record for the county occurred at the Cotswold Water Park (CWP) in 1994. Birds of Wiltshire recorded Cormorants present in 42 tetrads in summer though with no further evidence of breeding. It was not until 2009 that the next breeding attempt was recorded; WTA2 recorded confirmed breeding in two tetrads (one at the CWP and the other near Charlton-All-Saints on the River Avon south of Salisbury), probable breeding in two others and presence in 80 tetrads.


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.