When it was published in 1968, David Lack's seminal book Ecological adaptations for breeding in birds was years ahead of its time in explaining why life-history traits and mating systems vary so much across bird species. Nonetheless the intervening years have seen a number of important advances both in the study of evolution and ecology and in the quantity and quality of available data. In particular, Lack did not have access to modern comparative methods, which are able to examine ecological relationships after accounting for the possible confounding effects of phylogeny. Indeed, Lack did not use statistics to test formally any of his conclusions. Hence Bennett and Owens’ book is a very timely reappraisal of the questions posed in Lack's work. What's more, it's a highly successful one. The book is an absolute must for anyone with a particular interest in birds, and many of the evolutionary and ecological ideas presented are equally applicable to other animal groups: so much so that if you’re only planning on buying one book this year on evolution or ecology, this should be it. However it should be stressed that the book is not a review and the authors have not attempted a critical or exhaustive treatment of previous work in this field: indeed some of their citations are notably uncritical. Instead, the work is a research monograph in which the authors describe their own investigations.
The book is divided into four sections, the first of which discusses general problems of comparative analysis and provides a very useful and compelling introduction to modern comparative methods that seek evolutionarily independent origins of life-history traits. This section also provides a succinct summary of avian diversification and phylogeny. The next two sections reflect the book's provenance in examining competing hypotheses on how natural selection has resulted in life-history variation, and exploring how both natural and sexual selection have produced the observed diversity in avian mating systems. The fourth section is the most novel in terms of the questions asked, which reflect the rising interest in biodiversity and conservation by examining the ecological mechanisms that underlie variation in species richness and risk of extinction. In sections two, three and four, the authors present a wealth of original, rigorous and intriguing analysis, some of which confirms the early insights of Lack's work, but much of which leads to different conclusions and new insights, many of them unexpected or counterintuitive. Like all the best studies, the work also raises a number of further issues, and a separate chapter at the end of each section deals tantalizingly briefly with some of the more intriguing ones and indicates where more data are needed.
The book is very well written and the layout is excellent, with useful subheadings throughout and a succinct summary at the end of each chapter. The work is illustrated by numerous figures, tables and line drawings. In addition, there are four separate appendices giving very detailed and valuable information on key variables in different avian families. There are also separate author, family name and subject indexes that provide multiple points of entry into the text.
My one slight quibble with the book is that, whilst the authors have been careful to distinguish between the problem of explaining life-history variation and the problem of explaining population regulation, they have been less careful in distinguishing between life-histories (comprising sets of evolved traits) and life-table variables (such as hatching and fledging success) that indicate how life-history traits interact with the environment. This could cause some confusion, although it does not affect the authors’ overall conclusions and does not detract from the immense value of this work. At the end of the text, the authors issue a challenge to biologists working on other taxa to produce similar analyses to those in this book. It is only to be hoped that such analysis is forthcoming in the not-too-distant future.