Reed Warblers: Diversity in a Uniform Bird Family

cryptic, acrocephalids are not a prime example of a bird group that would have every biology student falling in love with them at first sight. Indeed, looking at these “universal brown birds,” one can hardly think of a less promising bird clade. But first impressions are, as Bernd Leisler and Karl Schulze-Hagen persuasively show, misleading. Take a minute and contemplate a couple of examples from this superficially boring family. Watch a group of five Seychelles Warblers (Acrocephalus sechellensis) caring for a single egg in the nest. Catch a glimpse of an infanticidal secondary female Great Reed Warbler (A. arundinaceus) as she visits the nest of a primary female—to kill her offspring before it even hatches. Follow a tiny Marsh Warbler (A. palustris) traveling almost half a year from its European breeding grounds to its South African wintering grounds on a road ~, km long—only to take the same treacherous trip back through inhospitable areas after just a couple of months of winter “holidays. ” Check the nest of the Aquatic Warbler (A. paludicola) with five chicks; there is a good chance each was sired by a different male. Furthermore, don’t forget that this last species, the rarest European migratory songbird, copulates ~, times (! ) longer than virtually any “normal” bird. The list could go on, only to confirm that the family of reed warblers is an ecological and evolutionary treasury full of enlightening surprises. Reed Warblers is divided into  chapters, each concluding with a succinct summary, and a final Postscript. The authors first introduce the group by imaginarily traveling across the diverse habitats and geographic regions that reed warblers inhabit. Recent advances in molecular phylogenetics have overthrown the traditional systematics of this group (a prime example of taxonomic splitting), with one quarter of extant species in this clade described during the past quarter of a century! Consequently, chapter  logically discusses current views of phylogenetic relationships among the six genera of Acrocephalidae (Nesillas, Calamonastides, Phragamaticola, Iduna, Hippolais, and Acrocephalus). In fact, phylogeny as a background for understanding among-species similarities and differences (divergence among closely related and convergence among distantly related taxa) is an organizing theme throughout the book. Consistent color-coding of the various acrocephalids enhances the user-friendliness of the book and is shown on the cover for quick reference. This makes it easy for readers to interpret the cluster-analysis results of various traits (nest design, body morphology, song traits, etc.) presented in different chapters. The authors, building on their long-term research experiences, pay meticulous attention to every aspect of acrocephalid biology. Chapters  through , on habitat and diet selection, show how this seemingly homogeneous avian group (exemplified by European members of the genus Acrocephalus) solved the problem of living in a seemingly homogeneous habitat (reedbeds and marshes) by very fine niche partitioning, ecomorphological differences, and interspecific aggression. The next three chapters focus on reproduction, ranging from the sometimes mindbogglingly complex song of reed warblers, through nesting per se, to interactions with the Common Cuckoo (Cuculus canorus). In fact, most of what we know about cuckoo–host coevolution comes from studies of Acrocephalus hosts. Uncannily, humans themselves have inadvertently “created” the Acrocephalus these are rather small issues among specialists who are equally passionate about how best to measure these animals that we study so intensively. The illustrations are excellent, making this book immediately accessible to the newcomer. The only caution I would give the novice is to also consult the literature to determine which measurements out of this universe of the possible are likely to be the best to take for a particular study. But even those of us who are old hands at measuring birds can benefit by exploring this universe to see whether new, alternate, or better methods can be applied. Everyone who measures birds would do well to study this volume. —Kevin Winker, University of Alaska Museum,  Yukon Drive, Fairbanks, Alaska , USA. E-mail: kevin. winker@alaska.edu