Penguins

Auk, The, Oct 2004 by Stokes, David

Penguins. -Lloyd S. Da vis and Martin Renner. 2003. Yale University Press, New Haven, Connecticut. 212 pp., 8 color plates, 27 data figures, 9 tables, line drawings by Sarah Wroot. ISBN 0-300-10277-1. Cloth, $40.00.How to make sense of penguins? Penguins are birds that forsook the air for the sea; they are highly specialized, but nonetheless occur over a wide geographic area and in exceptionally diverse habitats ranging from Antarctic to equatorial; and they comprise 16-18 species that are in some ways remarkably uniform, in other ways quite diverse.

Nearly everything about penguins, according to Lloyd S. Davis and Martin Renner in their excellent new book Penguins, is understandable as a consequence of the trade-offs inherent in penguins' unique double life, maintaining as they do, a foot-or flipper-in two worlds. The necessity of nesting, raising young, and molting on land but finding their food at sea explains much of the morphology, physiology, life history, and behavior of these birds that have long fascinated humans-scientists and nonscientists alike.

As the authors state in the preface, this book is not intended as a compendium of everything known about penguins. For that, a reader may be better served by Tony Williams' encyclopedic volume The Penguins (1995). Rather, this book calls to mind George Gaylord Simpson's 1976 classic Penguins: Past and Present, Here and There, which selectively treated aspects of penguin biology and evolution of particular interest.

Like Simpson, in writing a scientific book on penguins, Davis and Renner faced the unusual challenge of a subject that excites great popular interest and at the same time has proved to be a highly productive focus of scientific research. Indeed, the authors had a more daunting task than Simpson because of the welter of scientific contributions in the fields of behavioral ecology, animal physiology, and evolutionary biology resulting from studies of penguins in the last quarter century. Nonetheless, the authors succeed admirably, producing an accessible yet scientifically rigorous monograph with a new perspective on the biology, ecology, and evolution of penguins. Readers of all backgrounds will find it useful and informative. They will also find it highly engaging, as it effectively conveys the authors' contagious fascination for penguins and the scientific conundrums they present.

The book begins with an overview of the authors' central contention of the primacy of the interplay between penguins' evolutionary legacy of terrestrial breeding and current ecological conditions penguins face in the marine environment. That is followed by eight chapters, each of which addresses a major topic in depth. Each chapter frames the topic of interest in nontechnical terms at the outset with a minimum of references, allowing the interested non-specialist to fully grasp the ideas at play. The discussion then becomes progressively more detailed and technical, satisfying the specialist's desire for specifics and sources. With each new topic, the authors also include explanations of the methods used to obtain the information presented. That will be appreciated by all readers who are not already well acquainted with the particular research area.

The first of the subject-area chapters is a thorough treatment of the evolution of penguins, examining phylogenetic relationships among penguin species and between the penguins and their closest non-penguin relatives. Davis and Renner bring the reader up to date on the results of diverse approaches to resolving those relationships, from comparative morphology to molecular methods, as well as more speculative evidence based on patterns of behavior and host-specificity of parasites. The authors' synthesis of those results indicates that although the precise relationships remain unsettled, penguins' closest relatives appear to be the loons, petrels, and some of the Pelecaniformes. Interestingly, although loons do not use their wings to propel themselves in the water (as penguins do), morphological evidence suggests that the ancestors of loons did. Among the more interesting conclusions regarding relationships among current penguin species is that the Magellanic Penguin (Spheniscus magellanicus) appears to be more closely related to the African Penguin (S. demersus) than to the Humboldt Penguin (S. humboldti), with which it shares part of its range.

The section on penguin evolution is followed by a chapter summarizing the physical characteristics, distribution, natural history, and population size of each of the current penguin species. Those species accounts are short - generally less than a page-but are detailed enough to give a good sense of the differences among species, differences the authors address in following chapters. Of particular interest in this chapter is the discussion of the disputed taxonomic status of putative species, such as the Royal (Eudyptes schlegdi) and White-flippered (Eudyptula albosignata) penguins. The authors make a case for subspecific status for both (Eudyptes chrysolophus schlegeli and Eudyptula minor albosignata, respectively), but suggest that species status may be warranted for the Northern Rockhopper Penguin (Eudyptes chrysocome moseleyi), currently relegated to population or subspecies status by most authorities. Although this may seem an academic dispute of little relevance, I would add emphasis to the authors' statement that these matters have great practical importance, given the threatened status of many penguin species and the profound influence taxonomic status can have on allocation of conservation resources.