The water vole is widely distributed throughout Europe from the UK to eastern Siberia (5). It is widespread throughout Britain but is generally restricted to lowland areas beside water (2). Once a very familiar mammal of the British countryside, the population has undergone one of the fastest and most serious recent declines of any British mammal (5). The species has been in decline for many decades (6), and a national survey in 1996 to 1998 showed that the water vole had been lost from a massive 94 percent of sites (5) and had vanished from entire catchments in northeast Scotland, North Yorkshire and Oxfordshire (5).
The actual figure for habitat loss (from 1900) stated in the 1989-90 survey is 67.7%, and the figures for habitat loss (from the previous study) in the 1996-1998 study are 69.62% (baseline only) or 67.49% (baseline and historical). This would give total loss from 1900 until the 1996-1998 study of 90.2% or 89.6%.
The claim above that the 1996-98 survey showed a loss of 94% of sites is incorrect. This figure of 94% is from the earlier 1989-90 study by Jefferies and Strachan, and is an extrapolated figure - "Thus, we could eventually have a total loss of 94% of occupied sites this century and an even greater reduction in actual numbers." The actual loss reported in the study, since 1900, is 67.7%, although it may be as high as 77.2%. See Jefferies and Strachan, "The Water Vole Arvicola terrestris in Britain 1989-1990: Its distribution and changing Status", The Vincent Wildlife Trust, ISBN:0-946081-23-9