The ARC Rare Species Database

Quality Control

There are a number of records imported from third party datasets with grid reference issues to deal with, but nearly all ARC monitoring data are digitised using visual matching of locations on GIS. We do not record sightings that are unverified. A number of spurious records have been investigated and corrected since the last update in August 2012. The dataset has been checked using the NBN Record Cleaner.

Method steps

1. Most of the data are field sightings, largely the monitoring work of ARC employees, and volunteers recording on behalf of ARC. Species survey records are collated using one of two methods: (i) using printed or 'on screen' site maps to record an approximate location of an observed species, or (ii) using a Global Positioning System (GPS) device when a species is recorded in the field to obtain a grid reference location for an observed species. It must be noted that use of species location data from the ARC Rare Species Database is reliant on the accuracy of data recording and input methodologies. Location data within the past 10 years is considered to be more accurate due to advances in GIS technology and the wider use of GPS devices. The species records within the dataset do not state which method of recording a species was used, though an estimation of record accuracy is provided. BHS data were digitised by the BHS before 1998, and imported electronically with no verification or validation by ARC. All other data is entered into our database only if we are confident of its validity.

ARC has complete geographical coverage for all known natterjack, sand lizard and smooth snake populations in Britain. Our widespread species coverage is not comprehensive as it largely reflects incidental recording at rare species sites. Exotic species coverage is not complete either. The NARRS project (www.narrs.org.uk) aims to fill these gaps. The dataset 'NARRS Data 2007-2013' is also available on the NBN Gateway.