Antipredator Defenses in Birds and Mammals. Tim Caro. University of Chicago Press, Chicago, 2005. 591 pp., illus. $38.00 (ISBN 0226094367 paper).
Predation is an important factor shaping the natural world around us. Very few animals are neither predator nor prey. It is stating the obvious to say that being predated has a detrimental effect on the fitness of an individual, but even the threat of predation can have a major effect on reproductive fitness. A lucky rabbit may live to grow old and die peacefully in its sleep, but you can be certain that a large part of its life was taken up with vigilance against the fox, time that could perhaps have been spent gathering food or finding a mate. It is thus no surprise that antipredatory adaptations are both commonplace and diverse.
These adaptations do not get the attention that their ecological and evolutionary importance deserves, and I'm not certain why. It may be that because they are so much the stuff of elementary ecology courses, many mistakenly think that antipredatory defenses are well understood and that no exciting and important work remains to be done in this field. It may be that we prefer not to think about just how “red in tooth and claw” the natural world is. Or it may be that many researchers are put off by the ethical challenges of studying predation in the laboratory and the logistical challenges of studying something as unpredictable in time and space as predation in the field. No matter why, there is a mismatch between the importance of predation and its ability to attract bright minds and research funding. I hope this excellent book goes some way to changing this.
In a sense, this book does exactly what you'd expect from the title, Antipredator Defenses in Birds and Mammals: It provides a comprehensive overview, available nowhere else, of the antipredatory defenses of these two very intensively studied groups of animals. One of the reviews excerpted on the volume's back cover describes it as encyclopedic, and in a sense this is true; I've had it for six months, and every time I've reached for it to check on something, I've found what I was looking for. This book is comprehensive, but it also goes beyond thorough cataloging. The author, Tim Caro, provides a strong overarching structure that helps readers understand the question of why an animal might evolve one defense in preference to another. This structure comes from the highly influential framework of John Endler, which breaks the predation event down into a sequence of situations, starting before the predator has even detected the prey, and moving through detection, identification, pursuit, capture, subjugation, consumption, and even postingestional consequences for the predator. Hence a recurrent theme of the book is that defenses can be truly understood only in comparison to plausible alternatives and in the context in which they are deployed in the sequence of predation. The book gathers further conceptual strength from the author's willingness to go beyond the headline conclusions of published works, and to take the bones of data collection apart to see how the conclusions stand up. Finally, the book ends with a bold and thoughtful chapter on the author's vision for the way ahead for research in this area. This chapter alone justifies the modest cover price of the book.
It seems logical to ask why the author has confined himself to birds and mammals. I think some specialization is necessary if proper depth is to be maintained. I was recently involved in writing a book that also explored antipredator defenses (Ruxton et al. 2004), and we confined ourselves to a small subset of antipredator adaptations (crypsis, warning signals, and mimicry), in the hope that three authors could possibly gain some mastery over the relevant literature. As a single author with an interest in preserving his sanity, Caro had to specialize. He is currently a professor in the Department of Wildlife, Fish and Conservation Biology and the Center of Population Biology at the University of California; his research has mostly been concerned with large mammals. He has been personally involved in some of the most influential works on antipredatory traits in this group. It was logical to extend the focus to birds, since birds and mammals share many antipredatory traits, and birds are probably the most studied group when it comes to antipredatory defenses. By specializing in these two taxa, Caro could gain mastery over a diverse literature, giving appropriate attention to the latest breakthroughs and to often-neglected earlier works. Further, Caro is not overly strict in his taxonomic specialization. Where vital works in support of his arguments come from taxa other than birds and mammals, he sensibly admits these, while staying true to his main taxonomic focus.
In short, this book is clearly and intelligently written by someone with a broad understanding of antipredatory traits in diverse taxa. It could be read with profit by active researchers in predation looking for stimulation; by those with a more general interest in mammals and birds who are looking for a readable, reliable, and comprehensive reference in this area; and by undergraduates in courses related to ecology and animal behavior. The thoughtful text is well supported by highly appropriate graphs, diagrams, and tables selected from the relevant primary literature, and by a comprehensive set of indexes. I can think of no better recommendation than the considerable number of my colleagues who have bought their own copy after having found themselves reluctant to ask me yet again to lend them mine!