They often involve a large numbers of volunteers to cover a wide geographic area and the methods used are standardized so that the studies can be continued in the future and the results remain comparable.
Migration atlases on the other hand cover migratory birds depict maps showing summaries of ringing and recoveries.
[1] The earliest published mapping of biodiversity in the form of an atlas was completed for the flora of Britain - Atlas of the British Flora (1962)[2] The first bird atlas, the Atlas of breeding birds of the West Midlands, covered Staffordshire, Warwickshire and Worcestershire (England) and was published by Collins for the West Midland Bird Club, in 1970.,[3] It built on work done by the Club and its subsequent president, Tony Norris, for its West Midland Bird Distribution Survey, circulated privately in 1951,[4] which mapped frequency of sightings and breeding densities against districts based on the boundaries of Rural District Councils.
The method of collecting data, time and season in which to obtain the sample information are pre-decided as part of a protocol.
In some cases the numbers and species of birds that are found to be breeding are recorded, others may use timed point sampling or transects within the grid cells to obtain quantitative estimates of abundance.
[10] The Oregon Breeding Bird Atlas addressed this by using hexagonal survey units, which cover a spherical surface such as the earth without changing size.
[12] Recommendations and guidance stemming from the cumulative experience of state and provincial atlas projects is provided in handbooks of the North American Ornithological Atlas Committee (NORAC), published in English, French, and Spanish[13][14] Another approach that does not need pre-defined grids makes use of the coordinates of individual points.
[10] A framework has also been developed to incorporate monitoring data, hierarchical modelling and sampling simulations to augment occurrence and breeding status maps with species abundances.
The data itself cannot be recovered back from published atlases for alternate applications unless made separately available as an electronic database.
They provide information on the current distributions of birds and may be used by birdwatchers to assess the importance of their own observation records, learn more about species, or to plan trips.
The Southern African Bird Atlas Project (SABAP) was started in 1986 with data gathered from six countries: Botswana, Lesotho, Namibia, South Africa, Swaziland and Zimbabwe.