Detailed Devotion

Abstract

Otters: Ecology, Behaviour and Conservation. Kruuk, H. 2006 . Oxford University Press , Oxford , United Kingdom . 265 pp. £60.00 (hardcover). ISBN 0-19-856587-9 . In Otters: Ecology, Behaviour and Conservation, Hans Kruuk sets out on the daunting task of writing a book focusing on the world's 13 species of otters, which, collectively, are widely distributed among various aquatic habitats on 5 continents. Actually, describing the book as “focusing” is a bit of an overstatement in that Kruuk relies heavily on his research and conservation experiences with the common or Eurasian otter (Lutra lutra) to establish a framework for many of the topics covered in this 14-chapter book, rather than systematically profiling each otter species. Nevertheless, unlike Kruuk's previous book (Wild Otters: Predation and Populations 1995), which is primarily about the Eurasian otter, with emphasis on the pioneering research he conducted along the shores of the Shetland Islands off northern Scotland and in riverine systems in northeast Scotland, this book uses that early research to structure meaningful and logical discussion of various aspects relevant to studying and conserving all species of otters. Obviously, there are limitations when a synthetic approach is applied to the treatment of 13 species, especially if someone is hoping for in-depth discussion or a detailed reference guide for each of the species. Regardless, a segregated species-by-species review was not the author's intention and is not practicable given that many of the world's otter species have been poorly studied. In the preface Kruuk identifies the book as being “for naturalists, scientists, and conservationists, in fact for anyone who takes an interest in these animals and their vicissitudes, in Europe, America, or anywhere in the world.” Again, as in his attempt to provide a coherent treatment of ecological, behavioral, and conservation-related aspects of 13 species of otters, Kruuk's choice of such a wide audience establishes the further challenge of fitting the needs of readers with various levels of training and interest. Nonetheless, in our opinion, Kruuk generally succeeds in both areas. Kruuk is perhaps the only person with the diversity of experience and scientific credentials with otters (and perspectives gained from a life-long professional career with carnivores in general; see his book, The Spotted Hyena: a Study in Predation and Social Behavior[1972], as an example of his background in carnivore ecology and behavior) to successfully construct a publication of this scope. He brings to the book unquestionable scientific credibility (appropriately incorporating 40 first-author citations, 25 of those on otters) and dedication to the conservation of otters and their habitats. Kruuk's commitment to applying scientific methodologies in explaining natural-history observations and addressing conservation issues is evident throughout the book. We thoroughly enjoyed the manner in which science, natural history, and conservation are interwoven. Nevertheless, a reader looking for a quick reference on the natural history of a particular species of otter (i.e., a field guide to the otters of the world) may be disappointed. This is a book that needs to be read in some detail to be fully appreciated and, as the title aptly implies, it is devoted to the ecology, behavior, and conservation of otters. The book begins with a general overview of the natural history of the world's 13 species of otters (chapters 1 and 2), evolutionary relationships among species (chapter 3), and habitat associations for each species (chapter 4). The focus then turns to social organization (chapters 5 and 6), a lengthy discussion of food habits, prey availability, and foraging ecology and behavior (an area in which Kruuk has extensive experience; chapters 7, 8, and 9), coping with the physiological challenges imposed by a semiaquatic existence (chapter 10), and population structure and survival and mortality factors (chapters 11 and 12, respectively). The book ends with a synthesis of how the aforementioned topics relate to the ability of otter populations to persist in energetically demanding environments (chapter 13) and a discussion of conservation challenges related to direct (e.g., killing of otters for fur) and indirect (e.g., pollution of aquatic ecosystems) interactions between otters and people (chapter 14). Research and conservation information in the various chapters frequently is supported with clear, concise figures and charts. Throughout the book, Kruuk incorporates high-quality photographs of otters and otter habitats. Kruuk uses insight gained from his extensive research with Eurasian otters to establish structure in the book, which means most of his examples are derived from this species. Nonetheless, Kruuk has at least some level of expertise with most species of otters, which enables him to effectively interject informed comment relevant to a particular species. By necessity, though, the preponderance of the book devoted to “non-Eurasian” otters relies heavily on interpretation of the literature (of which the book includes a superb review). A reliance on literature in lieu of insight acquired through direct experience can somewhat limit an author's capacity to appropriately represent subtle aspects pertaining to the “ecology, behavior, and conservation” of a species. We noticed this as a minor limitation in some depictions of the North American river otter, issues discernable only because of our familiarity with the species. Generally, our concerns relate to subtleties in the manner that the literature was paraphrased in the book, in some cases offering potential for unique, localized events to be interpreted as typical for the species. We did detect a few specific errors in the book, such as at the beginning of chapter 12 (“Survival and Mortality”), where the method of age determination is incorrectly depicted as sectioning a tooth to reveal layering of the dentine (instead of the cementum), and in chapter 14 (“Otters, People, and Conservation,” which reviews the controversial issue of trapping otters for fur), where it is stated that the use of traps with “sharp teeth” are “still in common in use in North America,” this is not the case. Problems of the types mentioned are mostly related to the scope of the work and the challenges of synthesizing a large amount of detailed information for a large number of species occupying a large geographical area. Despite some limitations associated with the scope of this publication, Kruuk remarkably is able to integrate aspects of the life history and conservation needs of the world's 13 species of otters into a logical and coherent synthesis focused around a commonality—the challenges (energy demands) imposed on all species of otters by their dependence on aquatic environments. Throughout the book Kruuk aptly relates the manner in which thermal properties of water (high heat capacity) have contributed to what appear as remarkable similarities in the mechanisms otters have developed to meet thermoregulatory challenges (mostly through inferences derived from his research with Eurasian otters). Although these implied functional similarities (inferences) eventually may be demonstrated as not universally applicable among species, this need not be viewed as a negative attribute of the book because the “inferences” are presented in a manner that establishes direction for further research. In fact, Kruuk clearly elucidates approaches used in his research with Eurasian otters, which promotes ideas applicable to the study of all species of otters and demonstrates the value of developing research questions and testing hypotheses. Finally, we were pleased that issues related to ecological and conservation challenges for the survival of otter populations are prominently featured in the book, culminating in a synthesis of these topics in the final 2 chapters. In these final chapters, Kruuk challenges paradigms about otter conservation (e.g., otters require pristine aquatic ecosystems to survive) and identifies priorities, establishes rationale, and demonstrates his personal dedication for conserving the various species. We regard this book as essential reading for those with a specific interest in otters and their conservation or, for that matter, anyone interested in developing greater insight for research approaches applicable for effectively studying ecological relationships and natural-history aspects of carnivores.