Edited by Wayne R. Petersen and W. Roger Meservey. 2003. Massachusetts Audubon Society, Lincoln, Massachusetts. 441 pp., 225 watercolor paintings by John Sill and Barry Van Dusen, 198 range maps, 2 appendices. ISBN 1-55849-420-0. Cloth, $60.—A glance at the dust jacket of this handsome volume drives home the conservation message that breeding bird atlases are designed to promote—that bird populations are changing over vast areas and, unless we become aware of changes in status and take remedial action, some species will disappear from our neighborhoods and even our county or state. A case in point involves the closely related Golden-winged Warbler (Vermivora chrysoptera) and Blue- winged Warbler (Vermivora pinus). The males are shown in the atlas with their breeding distribution maps. When I was an active birder in the Boston suburbs in the 1930s, the Golden-winged Warbler was a common breeder and it was a treat to find a Blue-winged Warbler. The atlas map 40 years later (1974–1979) shows only five confirmed records statewide for the Golden-winged Warbler, compared with 73 for the Blue-winged Warbler, and the Golden-winged Warbler is now listed as endangered by the Massachusetts Division of Fisheries and Wildlife. Nationally, it is a species of management concern.

After a foreword and acknowledgments, this atlas begins with five very brief introductory chapters: history of the project, Massachusetts breeding bird distribution, Massachusetts ecoregions, atlas methods and criteria, and an introduction to the maps and species accounts. Massachusetts was the first state to embark on a state-wide grid-based avian atlas project. The organizers followed the procedures established by The Atlas of Breeding Birds in Britain and Ireland (Sharrock 1976) and endorsed by the International Bird Census Committee. The standard block size in Europe is 10 × 10 km, but small countries are using a 5-km grid, and county atlases in Europe are using a 2-km (tetrad) grid. The Maryland Ornithological Society had conducted a pilot study in two counties using standard 7.5-minute U.S. Geological Survey topographic maps (Klimkiewicz and Solem 1978). When divided into six equal parts, each atlas block at that latitude was almost exactly the same size as the European 5-km block. Blocks are slightly smaller at the latitude of Massachusetts, but most eastern states, including Massachusetts, have found it convenient to use the same latitude-longitude sampling frame. Massachusetts organizers elected to include every 5-km block in the state, whereas neighboring Vermont and New Hampshire and later many other states have randomly or systematically sampled only one block per 7.5-minute quad for lack of sufficient personnel. Before initiating the statewide atlas fieldwork, workers had successfully surveyed six Massachusetts quadrangles in 1973 to test the atlas protocol. More than 600 observers participated in the six-year project.

The Distribution chapter discusses the arrival of new breeding species in the state during the past century and likens bird distribution to a series of polygons of different shapes and areas. Sixty-one percent of Massachusetts breeding bird species nest continentwide. A discussion of bird habitats refers the reader to regional references. Thirteen ecosystems are mapped and briefly described.

The Methods section shows a field card and lists the standard atlas codes. The Massachusetts maps use the accepted convention of three degrees of certainty of breeding: possible, probable, and confirmed. Overlays in the back pocket permit researchers to study bird distribution in relation to elevation, habitat, and climatic factors and to recognize individual spots on the map. I do not buy atlases for their bird pictures, but I must point out that Sill’s and Van Dusen’s gorgeous watercolor paintings of birds in their breeding habitats are outstanding. This is the fourth North American atlas to display the birds in full color. The maps, on a county background, are large and neat and easy to read.

The accompanying text, contributed by 90 authors, describes the nesting habits of each species and the winter range of those that go to the tropics. It is so neatly edited that it appears to have been written by a single author. The text is very readable, with a minimum of references, which are largely initials of authors or publications that are identified on page 23. Clutch sizes for Massachusetts nests were obtained from the nest record file at the Cornell Laboratory of Ornithology.

Twenty species that were not confirmed during the six-year field period are discussed briefly in Appendix 1. Appendix 2 lists plant and animal species other than birds that are referred to in the text. A three-page bibliography precedes the index.

Massachusetts is well known for its many fine birding spots and its high density of knowledgeable bird enthusiasts. It may also be the state with the most state bird books. I now have six: Howe and Allen (1901), Forbush (1925–1929), Bailey (1955), Griscom and Snyder (1955), Veit and Petersen (1993), and Petersen and Meservey (2003). The Veit and Petersen book had already published small versions of most of the 1974–1979 atlas maps—those for which the distribution was believed to be unchanged since the fieldwork had been completed. However, the most dynamic maps, those showing active change, have not previously been published. Breeding bird atlases for all the surrounding states were published between 1985 and 1994.

Although the atlas passed through half a dozen editorial processes over the years, no one noticed that all the percentages of possible, probable, and confirmed records were based on 1,116 blocks (186 quads × 6) instead of 969, the number of atlas blocks in Massachusetts. Many of the quads extend into surrounding states or over open water. So Song Sparrow (Melospiza melodia), for instance, had been found in 97% of the blocks surveyed rather than the 84% indicated, and the observers had done much better than they were given credit for. All the percentages in this book should be multiplied by 1.15 when making comparisons with coverage in other states and provinces. I was disappointed not to see any summary statements regarding what was learned from the atlas work. Readers will also notice the absence of quantitative data. There are no counts, estimates, or trends. But remember, this was the first atlas started, and it was not until the Ontario folks asked observers to estimate the number of individuals nesting in each 100 km² of territory that atlas organizers began to think quantitatively. Those interested in population levels or trends in Massachusetts birds can obtain this information from the Patuxent website:  www.pwrc.usgs.gov/birds/.

This is one of the most handsome bird atlases ever published, and one of the most interesting distributionally because of Cape Cod and the offshore islands. Why is the Chipping Sparrow (Spizella passerina) widespread on Martha’s Vineyard and all but absent from Nantucket, whereas the threatened Vesper Sparrow (Pooecetes gramineus) was found in four blocks on Nantucket but was absent from the Vineyard? This book belongs in all academic libraries throughout the New World and in the personal collections of New England naturalists and conservationists.