Bird Atlas 2007–11 was a resounding success with over 216 million birds of 520 species and subspecies recorded from over 3870 10-km squares during the four years of fieldwork. These records came from over 182,000 Timed Tetrad Visits, 3.8 million Roving Records and 4.5 million BirdTrack records. The majority of these records were submitted by over 17,000 observers using the BirdAtlas and BirdTrack websites. Additionally, records were sourced from BTO and BirdWatch Ireland surveys and projects, Bird Clubs archives and data from NGOs and species specialist groups. The figure below indicates the main data sources incorporated into the atlas. In total data were sourced from approximately 40,000 observers.
Full details of patterns of coverage and effort can be found in Chapter 5 of the Bird Atlas book. For a short overview see results: coverage. See also here methods: monitoring progress for examples of how we gauged effort through the project in order to identify critical gaps in coverage.
Distribution maps for 296 species are presented in Bird Atlas 2007–11. For many of these species we also show change maps indicating how distributions appear to have changed since previous atlases. It was impossible to publish in the book all the distribution, change and abundance maps for 520 species and subspecies. Instead, an online appendix containing all these maps, and distribution maps from previous atlases will be available shortly.
Although the focus of much of the Atlas has been on mapping the distributions of individual species, the comprehensive nature of the atlas makes it particularly amenable to looking at broader patterns across species. Chapter 6 of the Bird Atlas book reviews some of the main changes occurring for groups of species defined either by their taxonomic affinities, or their use of particular habitats or landscapes. One of the key findings has been that breeding waders, as a group, are faring particularly poorly. This is just one of several avenues of research we are keen to follow.