RSPB Big Garden Birdwatch winter sightings in the UK in 2008

Quality Control

Observations were made and submitted by the public. The data has been mapped and checked. Species-specific filters were used to remove anomalously high counts and obviously out-of-range reports. Although the level of misidentified records may be higher than in datasets collected by more experienced observers, this is mitigated by the large sample size and standardisation between years.

Method steps

1. Volunteers sat and watched birds for one hour during the last weekend of January, and counted the highest number of each bird species seen at any one time (not counting birds flying over). Volunteers were provided with a Counting Sheet to tally the numbers of birds, and pictures of the most common birds seen in gardens. Data was submitted to the RSPB online or using a mail-in form.
   
   In order to verify records and validate the dataset, the data have been mapped and checked. The distribution of the species has been approximately checked using species-specific filters to remove anomalously high counts and reports well outside the expected range. The level of misidentified records may be higher than in datasets collected by trained field-workers but this is mitigated by the large sample size.

UK wide. Grid references were generated from the central point of full postcodes. Within this dataset, there may be some bias towards the more populated areas of the UK.