Timothy Brush. 2005. Texas A&M University Press, College Station. xiv + 245 pp., 41 color photographs and illustrations, 6 maps, 2 tables. ISBN 1- 58544-436-7. Cloth, $50.00; paper, $24.95.—Texas possesses a remarkable biogeographical brew of bird species. More than 600 species of birds have been documented to occur in the state. South Texas, in particular, is renowned among birders for its overall species richness and unusual mixing of avifaunas. Nesting Birds of a Tropical Frontier conveys the sense of perplexed wonderment at being in a place of fantasy—a place where temperate migratory species approach their southern range limits in winter, where Neotropical migrants surge through in multiple waves in the opposite direction in spring and fall, where breeding birds typical of the western United States and the southwestern borderlands reach their eastern range limits, and where tropical species widespread in Mexico and Central America breed at the northern periphery of their ranges. Nesting Birds of a Tropical Frontier also captures the excitement of working along the Rio Grande, one of the great rivers of North America, even though it has been altered dramatically (and irrevocably) within the past century by dam and reservoir construction, regulated flows, and accelerating demands for water for intensive agriculture and burgeoning human populations.

It can be said that the more difficult it is to classify a book, scientific manuscript, or article, the greater its relative merit, for this indicates that it bridges gaps in knowledge and perspective that are not filled easily by more traditional publications. This book is such a creation. It contains a systematic presentation of bird species accounts, yet also possesses elements of a field guide. Brush synthesizes material from multiple disciplines (e.g., cultural and environmental history, landscape ecology and community ecology, and biogeography), while narratives of his own experiences make the book partly a personal memoir.

Brush's goals in writing Nesting Birds of a Tropical Frontier were to (1) present an overview of past and present diversity and ecology of breeding birds and habitats of the Rio Grande Valley and (2) share personal experiences of working in and near the valley. In relating accounts of first-hand experiences gained while working in remaining fragments of dense riparian forest, and by juxtaposing those with descriptions of the Rio Grande floodplain penned by observers of long ago, Brush evokes the awe of what this great river once was and the sadness of realizing what can never be again. In writing this book, Brush has relied on personal field experiences and investigations, class field trips, students' research, books and articles, and field reports and observations of ornithologists and birders. Some of the latter have taken the form of electronic reports of rare and unusual bird sightings posted to listserves. Heavy reliance on information gathered by birders is noteworthy and demonstrates the value of birders in contributing to modern ornithology (e.g., strong participation of birders in Breeding Bird Surveys and Christmas Bird Counts).

The first part of the volume is devoted to an introduction and five relatively short, but informative, chapters on the environment, history, and biogeography of the lower Rio Grande Valley. An overview of physical features (i.e., geography, geology, climate and weather) of the valley is presented in the first chapter, along with the role of the Rio Grande as a main artery in an interconnected network of riparian and forested dispersal corridors in the semiarid Tamaulipan Biotic Province of southern Texas and northeastern Mexico. The second chapter, on ecological diversity and history, describes the lower-valley region at the time of first settle- ment by Mexico in the mid-1700s and the major factors that contributed to subsequent changes through the 1800s (i.e., conversion of prairies and savannas to thorn scrub and thorn forest by long-term grazing of cattle, sheep, and goats) and the 1900s (i.e., land clearing for agriculture, rapid increase in human population, loss of natural hydrologic regime because of dam construction, and invasions by exotic plant species). Other short chapters provide overviews of the six basic habitat types found in the lower Rio Grande Valley, their characteristic birds, and the changing mix of bird species dictated by the progression of seasons.

The heart of this volume is the species accounts and summaries, including more than 170 bird species known as current or past lower-valley breeders. Treatment of species is intentionally uneven, favoring those species recognized as “South Texas Specialties.” This is an excellent “tilt” in writing this book, because birders and field biologists generally are hard pressed to glean information on these birds. For virtually all of these poorly studied species, knowledge of their life history, breeding biology, and management remains woefully inadequate. For each South Texas specialty species, informative sections on distribution, habitat, habits, other observations, and outlook are provided. Species widespread in North America but with minimal nesting records in the valley are reduced to a short summary paragraph or less.

My criticisms of Nesting Birds of a Tropical Frontier are fairly modest. Lists of maps, illustrations, and photographs would have been helpful to readers in navigating within the volume. Likewise, the unnumbered photographs and plates of birds and habitats of the lower Rio Grande would be more effective if they were linked to citations in the text. The maps are too small for their large informational content. Map legends are too small for easy reading, most maps are somewhat difficult to interpret, and in general the maps are excessively “busy.” Some typographical errors in the text eluded the editorial filter. Though not very abundant, they nevertheless give occasional pause at first reading. These concerns with the book layout are frustrating, but my overall impression of the volume is highly positive.

The species accounts contain important contributions, especially those of the “South Texas specialty birds,” which Brush has chosen wisely to emphasize at the expense of more widely distributed and better-known species. These contributions, which primarily are qualitative, are most evident in the careful attention paid to details on distribution and behavior in the species accounts. The large number of references (24 pages), with their wide sweep of subject material, is a valuable resource in its own right.

This book deserves a place on the shelves of personal, community, and university libraries that serve readers eager to learn more of the bird- life of the lower Rio Grande Valley and tropical species at the northern extremes of their ranges in southern Texas. Brush writes in the style of an earlier era, when reading scientific accounts was more a pleasing literary experience and less an arduous exercise in mathematical gymnastics. I recommend Nesting Birds of a Tropical Frontier for birders and biologists alike who share an interest and enthusiasm for the biological wonders of the lower Rio Grande Valley.