What is an Ornithological Atlas?
An ornithological atlas, or bird atlas, as considered by NORAC, is an active field project to map the distribution of all bird species in a region during a particular time period. Atlases typically bring together hundreds or thousands of volunteer bird watchers and professional ornithologists to cover as much as possible of a particular region. Typically, the region may be a state or province, but some atlases cover multiple provinces, while others may provide more intensive coverage of a smaller area such as a single county.
Atlases can be extremely valuable tools for bird conservation, providing information on the current distribution of birds and (if they are repeated) how this is changing over time. The data can be used to set priorities for conservation activities, including designation of protected areas, to define conservation objectives, and to monitor the effectiveness of conservation/management actions. They can help with identifying and locating Species at Risk, and developing strategies to protect them and their habitats. The information can help with land-use planning decisions at various scales.
Atlases are also valuable for education and communication, by engaging large numbers of volunteers with a range of experience. Unlike some monitoring programs that are only suitable for highly experienced biologists, atlases can use the talents of a wide range of interested birders whose level of contribution can match their abilities. Individual birders may contribute data ranging from a few observations of breeding activity to hundreds of hours of point counts or other quantitative surveys, all of which form part of the atlas.
Most atlases involve dividing up the region into a grid (e.g., 10 x 10 km squares) and carrying out intensive sampling within every square in areas with lots of people, or in a subset of squares in more remote areas. The grid cells may be based on UTM or latitude-longitude, and their size varies among atlases depending on the size of the region being covered; in some areas hexagon shaped cells have been used.
Traditionally, most atlases in North America have focussed on breeding birds, with a particular emphasis on finding breeding evidence for as many species as possible in each sample area. Confirmation of breeding remains important for many purposes, such as identifying critical habitat for rarer species or defining range limits for species away from the core of their breeding range, many atlases now have an increased focus on additional information.
Estimation of abundance (or more frequently an index of relative abundance) is increasingly recognized as valuable, because it provides information not only on the relative importance of different areas within a region, but also can provide information on population trends as atlases are repeated over time.
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