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Massachusetts Breeding Bird Atlas 1
Methods and Species Accounts
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.
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Atlas 1 Breeding Criteria
A set of standardized criteria, similar to those used in most other atlases, was used to establish the breeding status of species recorded during the Atlas 1 period. Species were classified as either "possible," "probable," or "confirmed" breeders by classifying their behavior. A list of the breeding criteria codes and the definitions of the accompanying behaviors that were used during Massachusetts Breeding Bird Atlas 1 follows.
Possible Breeding
Bird recorded in the breeding season in possible nesting habitat, but no other indication of breeding noted.
Probable Breeding
S - Singing male present (or breeding calls heard) on more than one date in the same place
T - Bird (or pair) apparently holding territory
D - Courtship and display; or agitated behavior or anxiety calls from adults, suggesting probable presence of nest or young nearby; brood patch on trapped female or cloacal protuberance on trapped male
N - Visiting probable nest site
B - Nest building by wrens and woodpeckers
Confirmed Breeding
DD - Distraction display or injury feigning; coition
NB - Nest building by any species except wrens and woodpeckers
UN - Used nest found (use this criterion with caution)
FE - Female with egg in oviduct
FL - Recently fledged young
FS - Adult carrying fecal sac
FY - Adult(s) entering or leaving nest site in circumstance indicating occupied nest
NE - Nest and eggs or bird setting and not disturbed or eggshells found away from nest
NY - Nest with young or downy young of waterfowl, quail, waders, etc.
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Data Entry and the Atlas 1 Maps
Two of the more monumental tasks associated with managing the Massachusetts Breeding Bird Atlas 1 project were compiling the breeding-confirmation data at the end of each field season and creating the final maps. It is important to point out that the "age of computers" was still in its relative infancy when the original data for this project were being compiled and when the mapping program was being created in the 1970s and early 1980s. Richard A. Forster, Massachusetts Audubon's Atlas 1 coordinator throughout most of the five-year project, shouldered most of the task of annually updating the breeding confirmation data for every block in Massachusetts.
Once the final data for each block were compiled, the information was turned over to David Stemple at the University of Massachusetts Computer Center. Stemple created a mapping program that used symbols to illustrate the level of confirmation for every species recorded during the Atlas 1 period, block by block, on a map of Massachusetts. Without his expertise and tremendous contribution to the project, the first Massachusetts Breeding Bird Atlas 1 might never have reached fruition. Prior to their publication in the hardcopy format, the original Massachusetts Breeding Bird Atlas 1 project maps and map symbols were variously modified and improved through the efforts of Dorothy Graskamp and Stephen D. McRae, director, Massachusetts Division of Fisheries and Wildlife Geographic Information Systems Program, and of Barry W. Van Dusen, book designer and artist.
Making the online maps was significantly easier than it was during the 1980s. To complete the online edition of the Massachusetts Breeding Bird Atlas 1 we imported the original data into ESRI ArcMAP version 9.1. We created base maps using data layers provided by MassGIS, and with the generous support of Mass Audubon's Jeff Collins and Tom Lautzenheiser, rendered a base map with layers of the block outlines, relief, major roads, the Connecticut River and Quabbin Reservoir, and neighboring states.
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Species Accounts and Common References
The data reflected in the maps that follow were collected between 1974 and 1979. No attempt has been made to update these data, as this would confound the chief value of any distributional survey, namely to serve as a clearly delineated benchmark with which to compare future surveys. Dramatic status changes during the late 1990s have been noted in the appropriate species accounts, and brief accounts of "new" species are described in the section Additional Species. Readers seeking additional information about the status, seasonal distribution, and migratory behavior of birds in Massachusetts should refer to Birds of Massachusetts by Richard R. Veit and Wayne R. Petersen (1993).
The species accounts represent the labors of 90 authors who were invited to compile relevant facts and add appropriate commentary for every bird species that was confirmed breeding in Massachusetts during the Atlas 1 period. Authors were selected because they either were particularly knowledgeable about or had a special interest in a particular species. The content of the individual species accounts, while pleasingly reflective of the writing styles of the different authors, provides information that is consistent in substance and should be of interest to general readers, birders, conservation strategists, and land-use planners. The accounts provide a brief overview of each species' historical status in Massachusetts, along with any notable geographic or ecological association revealed by the Atlas 1 effort.
Much of the general information in the species accounts has been distilled from Edward Howe Forbush's (EHF) Birds of Massachusetts and Other New England States (1925, 1927, 1929) and Arthur Cleveland Bent's (ACB) Life Histories of North American Birds (1919 to 1968). Five other resources consistently referenced in the species accounts are American Birds (AB), Bird Observer of Eastern Massachusetts (BOEM) (now Bird Observer), the Cornell Nest Record program (CNR), David Kenneth Wetherbee's (DKW) The Birds and Mammals of Worcester County, Massachusetts (1945), and The Chickadee (TC), a journal published by the Forbush Bird Club.
Besides including information obtained from these resources, the species accounts provide data on habitat preferences, vocalizations, courtship behavior, nest and egg characteristics, breeding chronology, fledgling data, the timing of annual molts, the status of each species after the breeding season, and other valuable or interesting information uncovered by the authors. Each species account is accompanied by an accurate full-color illustration by bird illustrator John Sill or Barry W. Van Dusen.
This volume is intended to be a comprehensive, useful, and attractive reference work on the breeding birds of Massachusetts. It should be emphasized, however, that it is first and foremost an atlas-a book of maps, painstakingly created out of many thousands of observations made by a small army of dedicated birdwatchers over a five-year period. The data represented in these distribution maps is a significant contribution to the ornithology of the Commonwealth that, we hope, will promote the conservation of the extraordinary bird life of Massachusetts.
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