Second only to the classic book by Harrison, this is a quality book that focuses on a specific set of the pelagic species. Groups not included in this book are the gulls, jaegers, terns, penguins, cormorants, pelicans, tropicbirds, and frigatebirds. I like having this narrower focus since it allows more plates and information to be included while maintaining a smaller sized book.

The artistry and the variety of plumages in the plates are excellent. Each species is shown with anywhere from 2-8 different angles or plumages. Some birds, such as the Leach’s Storm-Petrel, are shown on multiple plates to show direct comparisons with similar species. Wisely, a note is placed with these birds to alert you to where additional illustrations may be found on the other plates. The plates make good use of the space with 8-23 illustrations. Those with higher counts still do not appear too crowded since these often involve only the heads of the birds to show subtle differences. I found these extra illustrations, such as the bill variations for the Westland and White-chinned Petrels, to be very useful when using this book off the coast of Chile. My only small critique with the plates is the stark, shiny white background, which makes the paler-plumaged birds not stand out as much – especially in the bright sunlight when standing on the deck of the boat.

The text is arranged into two sections. One consists of brief identification notes found opposite the plates. These are brief but potent. The bulk of the species accounts is in the last half of the book. About one page is dedicated to each bird and is broken into these catetories: taxonomy, distribution, behavior, jizz, size, plumage, molt, and identification. At least half of the information is given towards plumage and identification. This is top notch information that covers the variety of races, subspecies, and color morphs. The notes on jizz are also well written and quite helpful to aid in the identification. These offer distinct pointers that might not be noticed otherwise.

The range maps, which must cover a large area for these widely wandering birds, do a good job at depicting the ranges. Of course, the vast area covered means these ranges are somewhat generalized. Where a species is more locally confined, the maps zoom in to be more specific.

This is a must-have book for pelagic excursions. Although the Harrison guide might offer some additional text, its age falls behind the many taxonomic changes addressed in Onley's book. Also, Harrison's book is simply bigger to handle with all the other seabird families included.

I’ve listed several related books below…
1) Seabirds: An Identification Guide by Harrison
2) Field Guide to Seabirds of the World by Harrison
3) Southern Albatrosses and Petrels: An Identification Guide by Harper
4) The Seabirds of Australia by Lindsey
5) The Complete Guide to Antarctic Wildlife by Shirihai
6) Sea Birds of Britain and Ireland by Cramp
7) Field Guide to New Zealand Seabirds by Parkinson
8) Ocean Birds of the Nearshore Pacific by Stallcup ( )