Second Atlas of Breeding Birds in Pennsylvania

Twenty years after the first Atlas of Breeding Birds in Pennsylvania was published, the Second Atlas of Breeding Birds in Pennsylvania brings our knowledge of the state’s bird populations up to date, documenting current distribution and changes in status for nearly two hundred bird species. More than two thousand dedicated birdwatchers completed surveys of birds across the state from 2004 to 2009. The data amassed reveal the distribution of each species and show changes in distribution since the publication of the first Atlas. Additionally, a highly trained survey crew carried out bird counts at more than 34,000 locations statewide. These counts tabulated not just species but individual birds as well, in a manner that—for the very first time—enabled precise estimates of the actual statewide populations for more than half of the 190 breeding species detected. In all, more than 1.5 million sightings were compiled for the second Atlas, providing an unprecedented snapshot of the bird life of Pennsylvania—and perhaps of any comparably sized region in the world.

The introductory chapters to the second Atlas describe and discuss recent changes in climate and bird habitats within Pennsylvania. The data gathered and summarized for this volume were used by the more than forty contributing authors to write comprehensive and authoritative accounts of each species. These accounts are illustrated by stunning photographs, usually taken somewhere within the state. Up to three maps per species show in fine detail their current distribution based on the second Atlas, changes in distribution since the first Atlas, and, for more than one hundred species, their abundance in Pennsylvania.

“All around us, the world is changing. Avian communities are in flux, new bird-monitoring technologies are emerging, and our very understanding of nature is evolving. Enter the Second Atlas of Breeding Birds in Pennsylvania. Employing state-of-the-art methods and technologies, this important book brilliantly and compellingly depicts the astonishing pace of change in the Keystone State's dynamic breeding bird fauna.”—Ted Floyd, editor of Birding

“A must-have for those with an interest in the birds of Pennsylvania.”—The Birdbooker Report

“[A] definitive reference and rich source of information for anybody interested in the nesting birds of Pennsylvania.”—Pennsylvania Birds

“An innovative feature of this work is an assessment of population size, not just distribution, of many of the species. . . . The second Atlas promises to be a vital tool for bird conservationists in Pennsylvania for many years to come.”—Mary Jo Casalena, Game News

“Many additional features, results, and insightful analysis are provided within the 616 pages of this full-color book. . . . This book brings our knowledge of the state’s breeding bird populations up to date.”—Mary Jo Casalena, Game News

“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. . . . 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. . . . 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 Birds in Pennsylvania is a worthy tenant.”—Troy Corman, Birding Book Reviews

“This [breeding bird atlas] may be the best ever, clearly and exhaustively analyzing the results of 106,952 hours of fieldwork by 1,896 observers covering 890,000 miles in 4,937 blocks from 2004 to 2009 in a standardized, replicable manner resulting in 656,723 records.”—H. T. Armistead, Choice

“The Second Atlas provides a great template for future atlas projects. Using available technologies, building partnerships for needed skill sets, and eloquently combining the knowledge, skills, and tools into a comprehensive coverage of Pennsylvania bird distributional data, nesting phenology, relative abundances by habitat types and detailed densities for singing males statewide must be most gratifying to the editors and the 2,000 or more participants.
“The Second Atlas is a valuable tool for Pennsylvania bird study for professional ornithologists, seasoned birders, and conservation-minded nature enthusiasts. Anyone planning to design a bird atlas project for their state should study this masterful and successful example. Any birder visiting Pennsylvania should be sure to have a copy of this book at home or in the car. This is a nice addition to any bird library because of the breadth of natural history information included.”—Brad Jacobs, Wilson Journal of Ornithology

Andrew M. Wilson is Visiting Assistant Professor of Environmental Studies at Gettysburg College.

Daniel W. Brauning is an ornithologist with the Pennsylvania Game Commission.

Robert S. Mulvihill is Ornithologist at the National Aviary.

Contents

Foreword

Acknowledgments

Regional Coordinators

Atlas Volunteers

Chapter 1: Introduction

Robert S. Mulvihill

Chapter 2: The Geography of Pennsylvania

Andrew M. Wilson and Bernd J. Haupt

Chapter 3: Habitats and Habitat Change

Andrew M. Wilson, Margaret Brittingham and Joe Bishop

Chapter 4: Atlas Methods

Daniel W. Brauning, Mike Lanzone, and Andrew M. Wilson

Chapter 5: Analytical Methods

Andrew M. Wilson

Chapter 6: Coverage and Results

Andrew M. Wilson and Daniel W. Brauning

Chapter 7: Contributions to Conservation

Douglas A. Gross, Sarah Sargent, and Catherine D. Haffner

Chapter 8: Interpreting Species Accounts

Chapter 9: Species Accounts

Appendix A. Former Nesting Species

Appendix B. Common and Scientific Names of Plants and Animals

Appendix C. Summary of Atlas Results by Physiographic Province and Section

Appendix D. Habitat Associations

Appendix E. Analytical Methods - Statistical Details

Appendix F. Summary of Breeding Season Data

Literature Cited

Index

CHAPTER ONE

Aims and Purposes

Most “first generation,” grid-based breeding bird atlases collected presence-absence data for nesting species, in order to provide the first-ever detailed “snapshot” of breeding bird distributions for the geographic regions they covered—counties, states, provinces, or entire countries. Pennsylvania’s first breeding bird atlas (hereafter “first Atlas”) accomplished this goal when it was conducted from 1983 through 1989: just over 2,000 volunteers collectively reported more than 83,000 hours in the field, and amassed a total of 318,600 records representing 210 different species, 187 of which were considered breeding birds in the state (Brauning 1992a). Many more individual observations were certainly made by volunteers for the first Atlas, but, ultimately, only one record for each species (representing the highest observed evidence of breeding) was retained in the final database. The comparable total of unique species-by-block observations for the second Pennsylvania Breeding Bird Atlas (hereafter “second Atlas”) was just over 350,000, representing 217 species, with 190 considered breeding. However, unlike the first Atlas, in the second Atlas many additional records of selected species within the same atlas block (even multiple observations representing the same level of breeding evidence) were collected and retained in the final database for the additional valuable information they could provide regarding breeding phenology and fine-scale distribution patterns (see Chapter Six).The collective contribution of the more than 2,000 volunteers who submitted records for the second Atlas not only added to the solid foundation established by the first Atlas, but will continue to help private and public resource organizations further effective, scientific conservation programs in the years to come.

As groundbreaking as they were, most first atlases did not tell us where—across the length and breadth of their overall distributional ranges—species were more or less common: an observation of a single nesting pair or one hundred nesting pairs within a block would be mapped in just the same way. Because geographic differences in abundance, particularly for species of concern, have obvious importance for prioritizing conservation efforts, tackling the challenge of introducing a measure of abundance (i.e., a third dimension of distribution) into the second Atlas was a high priority from the start of its planning in 2001. With advice from a number of experienced field biologists and biostatisticians, we devised a novel, logistically demanding point count protocol, with the express purpose of meeting a principal aim of the second Atlas: mapping not only distributions of the state’s breeding birds, but also estimating the true density of as many of them as possible. This customized protocol was executed in every full-sized (i.e., non-border) block in the state over the course of five years (see Chapters Four and Five for details). An important lesson learned from the first Atlas provided another set of challenges for the planning and execution of Pennsylvania’s second Atlas. Simply put, the specialized natural history of some bird species renders them particularly difficult to find without considerable, targeted effort. Thus, in the first Atlas, the final maps for most nocturnal birds, as well as some habitat specialists (e.g., marsh birds), primarily reflected where in the state atlas volunteers had made the extra efforts needed to find these species. It was impossible to know whether distributional gaps for these species in the first Atlas were real or an artefact of insufficient effort; that is, there was no real way to know whether a species was actually absent from a block or if it was simply missed. Because many of these same species are of particularly high conservation importance and concern in the state, specialized surveys for these species were built into the second Atlas to increase the likelihood that these notoriously difficult-to-detect bird species would, in fact, be detected in blocks in which they likely occurred (see Chapter Four). Now, in blocks where these specialized surveys were conducted for the second Atlas and the target species were not detected, we can have greater confidence (compared with the first Atlas) that they were, in fact, not present.

As another novel feature of the second Atlas, we encouraged volunteers to collect multiple georeferenced records within any given block for selected species of conservation importance (i.e., species in bold or italics on the second Atlas field cards; see Chapter Four). Although only one breeding record in one field season was needed to fill in an atlas block for a given species on the final maps in this book, we knew that multiple georeferenced records within the same block could provide better data to support analysis of environmental and habitat relationships for these species, and that these, in turn, could contribute to the work of conservation in the coming years. Taken together, these resources enabled our volunteers to generate a large, precisely georeferenced database of breeding records, particularly for important bird species of conservation concern in Pennsylvania.

Yet another twist in data collection for the second Atlas, compared with the first Atlas, was our attempt to collect information about the co-occurrence of breeding bird species and Pennsylvania’s state tree, the Eastern Hemlock. As we faced the rapid spread of the introduced Hemlock Woolly Adelgid from east to west across the state, the second Atlas provided a timely opportunity to find out just how many and which species might be negatively affected by any future losses of the hemlock component of Pennsylvania’s forests. Because hemlock cover cannot be distinguished from other “evergreen” cover in satellite land cover data, we encouraged second Atlas volunteers to be our “eyes on the ground,” reporting the amount of hemlock present in locations where they observed breeding birds. We requested that volunteers collect one piece of habitat data, especially in connection with confirmed breeding records, for all species. The provisional list of “hemlock-associated” species (see Chapter Six) will deserve closer attention and consideration in connection with the conservation impacts of the advancing Hemlock Woolly Adelgid on hemlock stands in Pennsylvania and surrounding states.

Last, but by no means least, we strived to greatly increase participation in the second Atlas by recruiting our volunteers from well outside the conventional birding community circles. Although the state’s organized birders clearly contributed the bulk of records to the second Atlas, we used various means, such as backyard bird forms, farmer forms, hunter/fisher surveys, scout projects, and classroom activities promoted through statewide news releases, in an attempt to “popularize” the second Atlas and to increase the number of people who had a stake in the final results. We stressed that “every single breeding bird observation, whether of a common species by a beginning bird watcher or of a real rarity by an expert birder, will put another one of our state birds ‘on the map,’ in the process adding measurably to our knowledge of the occurrence, status, and distribution of Pennsylvania’s birdlife.” In an effort to make as many people as possible aware of the aims and purposes of the second Atlas, and to continually recruit new volunteers, we printed newsletters (c. 15,000), The PennsylAvian Monitor, once or twice a season, and sent it not only to those already enrolled in the second Atlas, but also to every public library in the state and many other public distribution points (e.g., nature centers, nature shops, and state park offices). An ulterior motive was to bring more of the state’s bird watchers into the fold of local Audubon and other bird clubs, not only for the benefit of those clubs, but also to ensure a ready supply of experienced volunteers for the third Atlas twenty years from now!

Although the hoped-for successes did not follow from all of the aforementioned aims and aspirations of the Second Pennsylvania Breeding Bird Atlas, we strongly encourage the organizers of second and subsequent atlases to strive to improve the quantity, quality, and scope of data related to breeding birds, to take full advantage of new and emerging technologies and analytical methods and products, and to reach out to the many people whose interest in (and knowledge about) birds may not yet have led them to membership in a bird organization. The risk of overreaching seems less of a concern than repeating exactly what was done before, especially where there is a clear opportunity to do much more. We hope the second Atlas will, therefore, serve as a source of ideas and inspiration for others embarking on their first or next atlas. There is value in thinking of bird atlases not only as a follow-up to a preceding atlas, but also as a step forward for any succeeding atlas.

The welfare of the birds within any political jurisdiction—indeed, the health and vitality of the very environments that we humans share with birds—depends upon practical, up-to-date information that can support sound scientific conclusions which, in turn, can inform and promote effective and efficient on-the-ground conservation efforts. Like most good citizen-science projects, the second Atlas has produced far more data than can be summarized and incorporated in this book, and we look forward to making these data available to conservation biologists and land managers interested in understanding, fostering, and protecting bird diversity in the future. The book you are holding breaks much new ground compared with the first Atlas, but it is just one of what we hope will be a stream of important publications based on the voluminous data collected by thousands of dedicated volunteers and other field workers for the second Atlas.

Nature

Pennsylvania & the Mid-Atlantic

           Nature