Birds of Delaware.—Gene K. Hess, Richard L. West, Maurice V. Barnhill III, and Lorraine M. Fleming. 2000. University of Pittsburgh Press, Pittsburgh, PA. xvii + 635 pp., numerous black-and-white illustrations, graphs, tables, and distribution maps. ISBN 0-8229-4069-8. $65.00 (cloth).
Located along Delaware Bay and the Atlantic coast, the state of Delaware's significance for bird conservation has been well established for decades. The extensive tidal habitats and marshes bordering Delaware Bay host shorebird and waterbird populations of hemispheric importance, and protecting these populations has become an urgent conservation priority in recent years. Other habitats found in the state vary from barrier beaches to dry coniferous woods on the coastal plain and mesophytic communities along the Piedmont in the north, allowing a diverse avifauna to prosper within a small geographic area. Ornithologists and birders have actively studied birds within the state for more than a century, but surprisingly, no single reference has provided a complete summary of the status and distribution of the state's birds until publication of the Birds of Delaware.
This book initially was intended to be only a breeding bird atlas, but its scope was later expanded. The format of Birds of Delaware is similar to other state bird books. The first chapter briefly summarizes the physical features, climatological data, and vegetative communities that are essential for understanding the state's patterns of avian distribution. Two introductory chapters describe avian conservation and the history of ornithology within Delaware, while another two are devoted to the breeding bird atlas methodology employed in Delaware and understanding the atlas results presented in the species accounts. Most of the book is devoted to these species accounts, describing the status and distribution for the more than 400 species reported within the state's boundaries. The appendices describe in detail some of the data sources used in the species accounts, summarize information on population trends, and estimate the sizes of statewide breeding populations for each species.
For many species the primary emphasis of the accounts is the results of the Breeding Bird Atlas project conducted between 1983 and 1987. These atlas data are the strength of this book. For each breeding species, the atlas results are described in detail and accompanied by maps exhibiting statewide patterns of distribution and relative abundance. This information is placed within the context of the species' historic breeding status and distribution, which for some species extends back into the early eighteenth century. Each account contains summaries of the breeding habitat preferences and chronology of nesting activities. However, this information is as likely to be gleaned from studies conducted outside of Delaware as from studies within the state, and its applicability to Delaware can be rather tenuous. Unfortunately, these atlas data are already 13 years old at the time of publication and updated in only a handful of accounts. Any changes in the status and distribution of the breeding species during the 1990s are poorly documented.
While all state bird books are out of date as soon as they are published, the absence of timely information is clearly evident in this book. The species accounts contain reports only through 1995, and a brief addendum hidden near the index highlights a few noteworthy rarities reported through 1997. Other data sources are even more out of date. Migration counts and estimates of Breeding Bird Survey population trends extend through 1991, while Christmas Bird Count summaries include data only through 1989. Hence, the Birds of Delaware effectively describes the status and distribution of birds as of the early 1990s rather than 2000.
A unique aspect of the Birds of Delaware is the eleven essays scattered among the species accounts, describing specific topics related to Delaware ornithology. These informative essays expand upon subjects only briefly addressed in the species accounts, such as Delaware's coastal impoundments and their birds, spring shorebirds on Delaware Bay, forest fragmentation and forest birds, birds and the law, and irruptive northern visitors to Delaware. These essays are not scientific treatises, but are aimed at a more general audience and at individuals unfamiliar with the state. This concept has merit and is worth emulating in other state bird books.
The species accounts also summarize status and abundance during the migration and winter seasons. This information is frequently condensed into single paragraphs for each season, although migration counts and banding information are used to complement field sightings for some species. Christmas Bird Counts provide much of the information for winter. To their credit, the authors provide citations for every report so that the original sources and observers can be independently verified.
Other aspects of the species accounts are disappointing. The authors included every species ever reported from Delaware, even those with no supporting documentation. More mystifying is the inclusion of species such as Eskimo Curlew (Numenius borealis), Red-cockaded Woodpecker (Picoides borealis), and others that have never been reported from the state. The authors' criteria for distinguishing between hypothetical reports and accepted records are subjective and inconsistently applied, as is their evaluation of the evidence that supports some of these reports. For example, my examination of evidence cited but not provided in this book indicates that a purported Three-toed Woodpecker (Picoides tridactylus) was actually an aberrant Hairy Woodpecker (P. villosus). The photos of the Mew Gull (Larus canus) pertain to a Ring-billed Gull (L. delawarensis), reflecting that the observer's doubts concerning this identification were ignored by the authors. Citing reports of accidental and vagrant species from the Birds of Delaware should be done with caution, and independent review of the supporting documentation is recommended.
The migration information is slanted toward the status of birds in the northern half of the state. Many species have different migration status and timing in southern Delaware, both in spring, when temperatures normally moderate more rapidly along the lower coastal plain, and in autumn when the passerine migration through coastal habitats differs markedly from their movements through inland locations. These regional differences are frequently poorly represented or sometimes dismissed as inaccurate simply because they do not conform to observations from northern Delaware.
The information for some species complexes does not reflect current bird identification standards. For example, no effort was made to distinguish the seasonal differences in status and distribution for dowitchers (Limnodromus spp.) and jaegers (Stercorarius spp.). The migration status of Empidonax flycatchers is based largely on specimen and banding data, ignoring the fact that many individuals are safely identified in the field with appropriate caution. Some valid reports were unfairly dismissed, such as October records of Semipalmated Sandpipers (Calidris pusilla), which regularly linger into the third week of the month.
The limitations of this book are significant, especially the information during the nonbreeding seasons and the inconsistent treatment of accidental and vagrant species. Some accounts accurately reflect the current status of species in Delaware, but others do not. The Birds of Delaware summarizes a considerable amount of information on the state's avifauna, but unfortunately provides an incomplete and somewhat dated picture of statewide bird distribution patterns. Despite these limitations, this book will still prove to be a useful resource for anyone with an interest in the avifauna of the First State.