Common Whitethroats breed throughout most of Europe (except for southern Iberia and the northern and higher regions of Fenno-Scandia and Russia), and also in northwest Africa, Turkey and Israel and across central Asia east to Lake Baikal and south to Iran. They all winter in sub-Saharan Africa, in the Sahel region from Senegal to Somalia and down east Africa to South Africa. They are very susceptible to weather changes along their migration routes. A severe drought in the Sahel in the winter of 1968-69 is estimated to have wiped out 77% of the previous year's breeding stock and led to a decline of between 50 and 100% in the populations of Common Whitethroats in various parts of west and central Europe.
    Once regarded as the commonest of the migrant warblers visiting Britain, their numbers reached an all-time low in 1974, then gradually recovered until further crashes in 1983-84 saw numbers fall to just 20% of pre-1968 levels. The last two decades of the 20th century saw a steady increase to a figure in 2000 estimated to be nearly 50% up from the total recorded in the 1988-91 Breeding Atlas. After that Bird Atlas 2007-2011 recorded numbers increasing by 43% between 1995 and 2010.
    In Wiltshire in the 19th century and most of the 20th they were regarded as so common that they warranted no more than passing references in the literature - until 1969, when the tone changed to concern about their sudden rarity. This was followed by a steady build-up until a 1979 report noted that they had re-occupied most of their traditional sites, though still not to pre-crash densities. Birds of Wiltshire recorded them in 802 tetrads, with breeding in 608. WTA2 found the number of occupied tetrads barely changed at 796, though the number where breeding was recorded had fallen to 523.

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: The Breeding and Wintering Birds of Britain and Ireland. BTO Books. 
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.