American Birding Podcast



Pennsylvania: The Second Snapshot

A review by Troy Corman

Second Atlas of Breeding Birds in Pennsylvania, edited by Andrew M. Wilson, Daniel W. Brauning, and Robert S. Mulvihill

Penn State University Press, 2012

586 pages, $64.95hardcover

ABA Sales / Buteo Books 13906


I was raised in rural south-central Pennsylvania, but moved away before fieldwork began in 1983 for the state’s first breeding bird atlas. Fortunately, though, projects like this are designed to be repeated, and when data collection for the second atlas started, twenty years later, I was able to spend a week or so of several consecutive Junes in the same forests and along the same streams and trails where my passion for the outdoors and birding had first taken flight, a passion that has guided my career path ever since.

Pennsylvania may not be a major U.S. birding destination, but its varied landscapes attract a remarkable selection of both resident and migratory breeding birds—at least 208 native and established exotic species are confirmed to have bred there, among them an amazing 30 species of warblers. That rich species diversity and the commonwealth’s long and impressive history of ornithological investigation is the subject of several books, including the first Atlas of Breeding Birds in Pennsylvania, published in 1992.

As dedicated atlasers already know, the production of a breeding bird atlas requires monumental effort on the part of hundreds, if not thousands, of skilled volunteer birders and professional ornithologists. And it all has to be repeated.  As the North American Ornithological Atlas Committee notes, “The tremendous value of breeding bird atlases will only begin to be realized when each state or province completes their second atlas. At that time, two ‘snapshots’ in  time of breeding bird distributions will be available for comparison and conclusions can be reached about the changes in distributions that have occurred.” Repeated atlasing, of course, also provides data on population trends, which can prompt research and conservation efforts for declining species and the habitats on which they depend.

Data for Pennsylvania’s second atlas were collected from 2004 to 2009, and the new book that resulted from that work provides us with an up-to-date overview of the current distribution and status of each breeding species, plus a tremendous amount of insightful analysis.

Early chapters in the Second Atlas discuss the goals and purpose of the project. The project framework and survey methods remained largely the same from the first to the second atlas, though there were efforts made to capture certain aspects missing from the first: For example, field crews were hired this time around to take point counts measuring the geographic variability of species abundance. One of my favorite sections in the new Atlas is the enlightening chapters describing the state’s geography, habitat, and land use. The many color maps and vivid descriptions provide a thorough introduction to the physical aspects of Pennsylvania’s environment that influence the distribution and abundance of the
avian life that breeds there.

Another brief chapter, “Interpreting Species Accounts,” greatly increases the reader’s appreciation of the many fine details to be gleaned from each of the 190 two-page accounts, prepared by no fewer than 52 authors. Those authors and the book’s editors—Andrew M. Wilson,
Daniel W. Brauning, and Robert S. Mulvihill—have taken full advantage of technologies and analytical methods that have emerged since publication of the first Atlas, making this second a sharply attractive, revealing, and masterfully prepared book.

Each species account includes a very good to excellent color photo, often, aptly, depicting adults at the nest or engaged in other breeding behavior. As expected, comparison of the data collected for each of the atlases is a significant part of these accounts; distribution changes (or their absence) are noted, and the Pennsylvania information is often compared with that discovered by second atlasing efforts in some adjacent states and provinces, thus placing apparent trends into a regional context.

Understandably, there is an obvious effort to avoid duplicating information already captured in the first Atlas. However, I find it mildly disappointing that so much natural history information has been omitted from the new species accounts. Appendix F in the Second Atlas provides a tabular summary of phenological data for most species; I would have liked to see some explicit discussion of the differences in breeding phenology discovered between the two atlases. Data continues to accumulate suggesting that the average timing of some species’ migration and nesting has already begun to shift, shifts possibly related to climate change.

The second page of each account features two or three easily interpreted statewide maps. The first and largest depicts where the species was detected during the second atlas. Any changes in distribution between the two atlases are clearly noted on the second map. In the case of more common and widespread species, a third map depicts the geographic density of singing males as determined by point counts. Each account also includes a table showing the number of blocks in which the species was identified by each atlasing project as a possible, a probable, or a confirmed breeder; changes between the two atlases are expressed as a percentage. Worrisome numbers include those for the Red-headed Woodpecker, which declined by 46 percent, and for the Golden-winged Warbler, down 61 percent between the two atlases. Compare that with the incredible increases in breeding Common Ravens—114 percent—and Bald Eagles—949 percent! These changes are discussed in detail in each account, with insightful suggestions as to why specific species have declined or increased, or why their distribution in the state has shifted.

Appendix A includes brief accounts for a dozen former nesting species and a table listing ten additional birds that have not been documented nesting in Pennsylvania since the 1970s or before, including the Heath Hen and the Passenger Pigeon. Oddly missing from this list is the Glossy Ibis, noted in the first Atlas as a confirmed breeder on the Susquehanna River in the 1970s.

Few other resources provide so complete a picture of bird distribution over time as a breeding bird atlas, and few are so helpful in the long-term monitoring of avian populations. It is hard to imagine that any birder would not want a copy of the Second Atlas, whether in Pennsylvania or anywhere in the region, a region that stretches as far north as Quebec and as far west as Ontario (both jurisdictions, by the way,  with magnificent atlas projects of their own). An exceptional summary of a large amount of data, presented in a sharp and impressive tome, this work sets a new standard for atlases to come.

It may take up a lot of space on your bookshelf, but as an informative and inspiring reference, the Second Atlas of Breeding in Birds in Pennsylvania is a worthy tenant. I am honored to be one of the many who participated in this endeavor. As much as I learned while helping collect data, I continued to be enlightened as I reviewed this fine resource.

Troy Corman is a biologist in the Arizona Game and Fish Department, where he coordinates long-term statewide bird monitoring projects. He coordinated the Arizona breeding bird atlas project and served as co-editor of the Arizona Breeding Bird Atlas (2005). Corman is president and a founding member of the Arizona Field Ornithologists. His interests include the distribution and seasonal status of birds, conservation, and travel.

Recommended citation:

Corman, T. 2013. Pennsylvania: The Second Snapshot [a review of Second Atlas of Breeding Birds in Pennsylvania, edited by Andrew M. Wilson, Daniel W. Brauning, and Robert S. Mulvhill]. Birding 45(3):67.