Avian Incubation: Behaviour, Environment, and Evolution.—Edited by D. Charles Deeming. 2002. Oxford University Press, Oxford, United Kingdom. xiv + 421 pp, numerous figures and tables, two color plates. ISBN 0-19-850810-7. Cloth, $85.00.—This book presents an up-to-date, exhaustively researched (∼1,600+ references) overview of how birds care for their eggs and maintain them at high temperatures. The book has 22 chapters, 7 of which are authored or coauthored by the editor, the rest including 27 additional authors from the United States, United Kingdom, Canada, Australia, Israel, and The Netherlands. Following an introduction on the evolution of incubation (Deeming), the chapters fit nicely into five topics, the first dealing with structural aspects of incubation and including incubation sites (M. H. Hansell and Deeming), egg characteristics (Deeming), and use of egg components by the developing embryo (Deeming). Chapters on behavioral aspects of incubation include hormonal control (C. M. Vleck), incubation rhythms (Deeming), and parent–embryo interactions (R. B. Brua). Heat is the central theme of the book, and it is covered in chapters on the brood patch (R. W. Lea and H. Klandorf), egg temperature (J. S. Turner), nest microclimate (A. Ar and Y. Sidis), and egg turning (Deeming). Many special situations concerning incubation are dealt with in chapters on the effects of nest microbes on incubation (G. K. Baggott and K. Graeme-Cook), the underground nests of megapodes (D. T. Booth and D. N. Jones), the smallest incubators, the hummingbirds (W. A. Calder III), models of intermittent incubation (F. R. Hainsworth and M. A. Voss), incubation in extreme environments (C. Carey), and the tactics of brood parasites (S. G. Sealey, D. G. McMaster, and B. D. Peer). Finally, ecological and life-history aspects of incubation are treated in chapters on the initiation of incubation behavior and hatching synchrony (P. N. Hébert), egg coloration (T. J. Underwood and S. G. Sealy), energetics of incubation (J. M. Tinbergen and J. B. Williams), and the incubation costs of reproduction (J. M. Reid, P. Monaghan, and R. G. Nager). A brief chapter by D. C. Deeming on areas for future research concludes the book.
The eggs of birds have long been a focus of research, from early studies of vertebrate embryology, summarized decades ago by Alexis Romanoff, to more recent work on physical gas exchange across the eggshell by the late Hermann Rahn and his associates. There has also been the considerable practical matter of maximizing the hatchability of the eggs of domestic fowl in convection incubators, the tradition from which the editor of this book has come. Regardless of how wonderfully convenient the avian egg has been for many areas of biological research, it nonetheless challenges the parent bird to keep the embryo inside at an optimal temperature. That requires a suitable combination of incubation site, nest construction, and application of heat, keeping in mind such constraints as safety of the nest and the parent's own maintenance. Avian Incubation admirably brings together highly readable and well-illustrated accounts of those issues, covering research on both domesticated birds and a wide variety of wild birds. It should serve as the starting point for all future studies of incubation, and the sections on “future research” at the end of most of the chapters emphasize that there is much more to learn.
From my perspective as an ecologist and evolutionary biologist, I am interested in the extent to which variation in incubation period is determined by the incubating behavior of parents as opposed to intrinsic attributes of embryos, and the fitness consequences of variation in incubation behavior and embryo development. By its nature, an edited book such as Avian Incubation has less synthesis between chapters to address such questions than I would have liked. Nonetheless, the overall coverage is broad and thoughtful, and several of the chapters explicitly integrate aspects of incubation through modeling. What impresses me most from reading this book is that the answers to many questions about incubation as a component of life histories demand an understanding of the complexities of the incubation process. For example, unlike a convection incubator, which warms eggs evenly, contact incubation establishes sharp gradients of temperature within the egg, which are greater across large eggs than small eggs. As a consequence, when the parent leaves the nest the initial phase of cooling is dominated by redistribution of heat within the egg rather than loss through the egg surface (Turner). That has implications for the maintenance of embryo temperature and the rhythm of incubation by adults (Hainsworth and Voss), and may explain why recess length increases as only the 0.4 power of egg or clutch mass rather than the expected two-thirds surface rule (Deeming). Also, I was intrigued to learn that gas conductance of Mandarin duck eggs increases during the incubation period as colonies of Bacillus bacteria break down the outer egg cuticle (Baggott and Graeme-Cook). What if birds use microbes to help adjust gas conductance (Carey) in parallel with the oxygen uptake and carbon dioxide production of the developing embryo? It would be a nice example of biological engineering!
Incubation and its place in the life history of birds is highly amenable to theoretical, experimental, and comparative analysis, as this book makes abundantly clear. I hope that Avian Incubation will inspire young investigators to continue the wonderful tradition of egg and incubation research.
