The task of identifying seabirds at sea, or even in their colonies, has undergone a revolution during the past 30 years, thanks to sonagrams, DNA techniques, and the genius of people like Steve Howell and others, who possess an unparalleled eye for detail, a photographic mind, an encyclopedic memory, a yearning to float the world's oceans with binoculars and camera in hand, and a yen to make their findings widely known. When I set off across the Pacific in the mid-1970s to investigate the “life zones”of the pelagic realm, California to Antarctica (three times), and to gauge their respective marine avifaunas, available to me (and my compatriots, Bob Boekelheide and George Divoky) were Murphy's Oceanic Birds of South America (1936, Macmil-lan Press, New York), Alexander's Birds of the Ocean (1954, Putnam, New York), two identification guides that were prepared by the Smithsonian's Pacific Ocean Biological Survey Program (1960s), and a preliminary version of Harper and Kinsley's Southern Albatrosses and Petrels: An Identification Guide (1978, Victoria University Press, Wellington, New Zealand). Woe was us! This was several years before the current “bible”to seabird identification appeared, Harrison's Seabirds: An Identification Guide (1983, Houghton Mifflin, Boston). Many of the species that we were encountering for the first time—new ones every day as we crossed the latitudes—were difficult to tease from the illustrations we had. We were forced to make extensive notes on each new species and later, as we sighted other species or visited museum collections, rule some of them out in a process of elimination toward correctly identifying the species in question. Then, of course, we had to go back to our data to update “species x,”and so on. Well, then came Harrison's book, a really valuable tool for the past couple of decades. Now arriving, however, is Petrels Night and Day, an example of the next generation of field guide. It's an exquisite contribution but “unfortunately”applies only to petrels breeding or occurring in the North Atlantic (and not even the Caribbean).

Owing to the revolution in genetic analysis of species, field ornithologists have been challenged to find newly described species out in life, in their habitats, because many of the “new”ones are very difficult to tell apart, even, sometimes, in the hand. An example is found in Harrison (1983) under the name “Soft-plum-aged Petrel (Pterodroma mollis).”As we learn in Petrels Night and Day, this bird has since been split, appropriately, into four species on the basis of DNA, phenology, and voice. In fact, the 26 species covered in Petrels Night and Day, all from just the eastern and northern North Atlantic, were described and illustrated as 16 species by Harrison. However, by honing one's observational skills and, if one is lucky enough to visit some of the islands where these birds nest, by having the vocalizations in mind as presented in this book, most of these “new”species can be told apart in the field, even in the dark, without doubt for most and with reasonable assurance for others. Petrels Night and Day provides lots of photos, very fine full-color drawings that compare distinguishing characteristics among similar species, as well as not only sonagrams but two CDs of field recordings as well. My mind boggles to think of the series of volumes that Robb and Mullarney, or others, will have to produce so that all the world's seabirds someday will be similarly covered, or even just the petrels. It would be a task similar in magnitude, I think, to unraveling the human genome.

This volume is divided into 12 chapters and also includes references and an index. Four chapters treat single species, for example, Manx Shearwater (Puffinus puffinus), and the remainder treat species groups, for example, gadfly petrels (Pterodroma madeira, P.feae, and P. deserta). Besides the sonagrams and recordings (with cross-referencing in the text), each chapter includes comparative drawings, maps of breeding locations, and the locations where recordings were made. The one item missing is range maps of known or suspected occurrence at sea, though this subject is discussed to some extent in the text for some species.

The text itself is mainly the edited field notes of Magnus Robb, with explanations of various pertinent phenomena sprinkled throughout in no particular order, such as how petrels make sounds, how to read a sonagram, the significance of molt in the annual cycle of a bird, etc. His field notes reveal the difficulties of finding an appropriate population of each species for vocal recording, often with the recounting of adventures experienced while gaining access to various islands. Therefore, the text in places is somewhat stream-of-consciousness. In a couple of cases, a heading identifying that another species is now being discussed is missing (and one could go on for a paragraph not realizing this), and in a few others information is provided only because some event occurred on a trip that elicited some thoughts—for instance, the text and photograph regarding Black-capped Petrel (P. hasitata) appearing within the text about Monteiro's Storm-Petrel (formal description not yet published). The Black-capped Petrel is not otherwise treated; an individual was encountered while searching at sea for the storm-petrel. Therefore, using the index is a must if one wants to find specific details, once having read through the book to get a sense for what is available. Included for most species, woven into the narrative, are a history not just of the species' existence, as told from the DNA and fossil remains, but also of how the species has been considered by taxonomists since its first description. Some extinct species are treated. Aspects of the lives of several personalities involved in discovering or protecting various species or populations can be found as well, with great interest and value. The derivations and histories of both the English and Latin names of species are included. Finally, each chapter lists the current (and sometimes former) breeding sites and breeding seasons, gives estimates of population size, and, in many cases, reviews attempts, successful or not, at conservation.

This is a great book, and I learned a lot from reading it. Given the high density of bird observers on either side of the North Atlantic and the long-time scrutiny they have been applying to “their”seabirds, as revealed in this book, I think it will be a while before the taxonomy and patterns of Pacific petrels will be equally understood, for they are distributed over a vast area, among a myriad of islands, with observers few and far between. Saying that, and contemplating how this book describes the unraveling of the taxonomy of the Madeiran gadfly petrels, I am acutely reminded of the Hawaiian Petrel (P. sandwichensis) that I am currently researching in the field (with J. Adams, J. Penniman, P. Ostrom, H. James, R. Fleischer, and students), a species whose phenology and voice—and genetics, too—appear to differ from one Hawaiian island to the next. And that is just one species and Pacific island group. Nevertheless, perhaps someday it will be possible to patch together this species' history in a way similar to the Madeira experience detailed in Petrels Night and Day. This book is exemplary for both its historical and its practical value and should find a place in just about any library containing books on birds.