DBRC Arvicola amphibius records 1925 - 2016

Quality Control

There is a medium to high level of confidence about the accuracy of the records within this dataset. For a small subset of records confirmed presence of water vole can only be considerd possible and further checks on these records are ongoing. The dataset has a comprehensive geographic coverage and records have been checked by DWT. This has resulted in the correction of obvious input errors (after reference to the primary data source) and highlighted where records required additional information in order to have a high confidence in their accuracy. Any records with a low level of confidence remaining after validation procedures have been excluded. Given the validation procedures and cautionary approach which has been adopted it is considered that there is a reasonable level of confidence in the accuracy of the dataset. This dataset has been checked with the NBN Record Cleaner.

Method steps

1. The dataset has been validated and maintained by Derbyshire Wildlife Trust and for the past 15 years training has been provided to field surveyors to provide them with the skills they need to identify positive field signs and to ensure interpretation of field signs is consistent. Many of the records have been generated as part of an ongoing monitoring programme focused on key sites across the County. Typically surveyors visit their site several times a year and walk a set distance along the watercourse searching for evidence of water vole activity. Most of this work is undertaken by volunteers. The data is initially stored in an Access database before being translated into the NBN format. Records are included where there are suffieicnt field signs or where a water vole has been seen.

The data relates to the administrative county of Derbyshire and records have been collected from across the entire County. However, in recent years there has been a focus on key monitoring sites in the County. The records are mainly site based, and as such many have been entered onto the Trusta^??s database using a six figure grid reference for the site. However, as sites comprise lengths of watercourse some will begin and end in different monads, tetrads or hectads.