England Otter Survey Database

As part of a scheme to monitor the distribution of otters throughout the UK, four England otter survey have been carried out covering the years 1977-79, 1984-85 and 1991-94, and 2000-02. In the first national survey, alternate 50-km squares - the north-west and the south-east quarters of each 100-km square - of the National Grid were surveyed to geographically represent cover of all regions (giving a total of 2940 in the first survey). The second survey (funded by The Vincent Wildlife Trust) in 1984-86 added four more 50-km squares (that were deemed unlikely to have otters in the first survey) giving a total of 3189 sites, all of which were re-surveyed in 1991-94 (The Vincent Wildlife Trust). In the 2000-02 (The Environment Agency) surveyed all alternate 50-km squares in England were surveyed, making the total of 38 50-km (and partial) squares and 3327 sites. Sites were selected by accessibility and likelihood of finding signs of otter activity - typically road bridges and the confluences of watercourses. The number of sites visited per square varied. The survey protocol was to search up to 600m of one bank of a water body from a starting point (grid referenced), either all in one direction or split between two directions. Searching stopped as soon as signs of activity were noted in the 1977-79 and 2000-02 surveys, the full 600m being surveyed in the intervening surveys. The number of spraints and presence of mink was also recorded.