Atlas 1 Methods
The information that follows is an abbreviated description of the basic techniques and procedures that were used by the volunteers in the Massachusetts Breeding Bird Atlas 1 project. For a more detailed account of atlas methods, please see the comprehensive Handbook for Atlasing American Breeding Birds, published online by the North American Ornithological Atlas Committee.
Breeding bird atlases follow a standard field technique and protocol, and have been completed for every state east of the Mississippi River, for several provinces in Canada, for the U.K. and Ireland, and for other countries, states and counties. Most simply described, an atlas divides the county, state or province into equally sized blocks or squares. Each square is surveyed for the presence of breeding birds. The breeding status of the species is determined by evaluating the behavior of the birds, and comparing what is observed to a set of predetermined breeding criteria. After all blocks are surveyed, the information regarding the strength of the breeding evidence is collated for all species in all blocks. This creates a data set of the distribution of all breeding species in the area—a detailed and repeatable snapshot of the distribution of the breeding birds.
The repeatable design is one of the strengths of the atlas methods and protocol. The results of one atlas project map the distribution of the breeding birds during a precise period in time. If the project is repeated twenty years later, a comparison of those data shows not only the distribution of the breeding birds, but how the distribution has changed over time.
The first Massachusetts Breeding Bird Atlas project collected data between 1974 and 1979, and achieved nearly total coverage of the state. To create the blocks, U.S. Geological Survey 7.5 minute topographic quadrangle maps were divided into six, equally sized blocks (approximately 10 square miles). Approximately 75 volunteer coordinators were responsible for managing block coverage and for directing the activities of more than 600 field volunteers during the course of the six-year Atlas 1 period.
No blocks or regions were assigned a higher priority than others. Full state coverage was made a priority, with the result that a complete survey of state habitats was obtained. Information was gathered for a total of 969 blocks, and only blocks on the borders of the state, where the quadrangle maps include only negligible Massachusetts's territory, were omitted. Although not every block in Massachusetts received an equal amount of survey time during the 1974 to 1979 period, at least some coverage was obtained in every full block. Full state coverage was possible because of the dedication of the volunteers who contributed time, expertise, and data to the Atlas 1 project.