Ber van Perlo. 2006. Princeton University Press, Princeton, New Jersey. 336 pp., including 98 color plates. ISBN-13: 0-691-12070-6 and ISBN-10: 978-0-691-12070-6. Paperback $29.95.—Do we need another field guide to birds of Mexico and Central America, when guides already exist for subsets of the region? Yes, there is always room for improvement. This guide's main strength is that it is more compact than most. Having all the information one needs in one very portable book is certainly handy. All species in the region are illustrated, including accidentals and hypotheticals—the only ones missing are Tricolored Munia (Lonchura malacca) and some recent accidentals.

The most important features in a field guide are user-friendly design, accurate illustrations, and concise information that complements the illustrations. A bad design can spoil excellent text or illustrations. Van Perlo's guide basically uses the facing-page format for plates and text that has proved to be the design of choice for field guides; it is quite easy to get accustomed to text sometimes spilling over to the next or previous page, and the range maps bunched together at the end of the book are well cross- referenced with the species' English name and plate number. Van Perlo generally did a good job of illustrating similar species in the same or adjacent plates (the few exceptions include scattering black raptors among plates 14–22).

The illustrations are the part of a field guide that will typically be used the most. By far, most of the illustrations in Van Perlo's guide are accurate. But there are unfortunate errors, such as the horizontal posture of Spotted Barbtail (Premnoplex brunnescens); Turdus assimilis lygrus is unrecognizable; the legs and feet of Solitary Eagle (Harpyhaliaetus solitarius) are too thin; the tail is too long in Common Poorwill (Phalaenoptilus nuttallii); and the beaks are too long in Atthis and Lamprolaima.

Illustrating birds to scale, especially within the same plate and family, is very important. Of course, illustrating condors and hummingbirds to the same scale is not practical in a field guide (in the 19th century, John James Audubon had to produce a double elephant folio to achieve just that), but an approximation within practical limits is worthwhile. Again, for the most part, van Perlo has done a good job. However, there are a few “oxymorons.” For example, in plate 24, Yellow Rail (Coturnicops noveboracensis) seems bulkier than Sora (Porzana carolina) and even wood-partridges (Dendrortyx spp.) but is the same size as wood-quails (Odontophorus spp.). Rails (in plate 23) seem smaller than crakes (in plate 24). In plate 38, parrots look smaller than the parakeets in plate 37. The hummingbirds in plate 46—from coquettes (Lophornis spp.) to lancebill (Doryfera ludoviciae)—appear to be similar in size.

Van Perlo states (p. 8) that the guide uses the scientific names of the AOU Check-list. However, some more closely follow Sibley and Monroe (1990, 1993). In a very few cases, van Perlo commits the ultimate sin in a field guide: the names are switched reciprocally between Sumichrast's and Nava's wrens (“Catherpes” sumichrasti and “C.” navai) and between Baltimore and Orchard orioles (Icterus galbula and I. spurius). Most flying falcons in plate 22 are mislabeled. Also, both species of Caryothraustes are given identical scientific names. The few typographical errors in the guide include Butorides “stratus,” “Ochraceus” Wren (Troglodytes ochraceus), “Guadelupe” Junco (Junco insularis) and “Columbia” instead of Colombia (p. 23).

The text of a field guide should be helpful and concise enough that reading it while having the bird in view does not become tedious. A detailed description of plumage is unnecessary, because that is what the illustrations are for—and as we have all heard, a picture is worth a thousand words. Lengthy descriptions of range, seasonality, and abundance are also unnecessary if they are provided in a map. In these respects, van Perlo's guide, and “illustrated check-lists” in general, are definitely on the right track.

Are the identification tips provided in the text helpful? Usually, but for some species, brevity resulted in incomplete or misleading text. The “easy to confuse with [Ruby-crowned Kinglet Regulus calendula]” under Hutton's Vireo (Vireo huttoni) could have been replaced by a more helpful “Thicker bill and legs than [Ruby-crowned Kinglet]” without sacrificing much space (additional details would be worth adding, especially because more space was available in this case).

Many of the following examples are attributable to the extreme brevity of the text, combined with suboptimum illustrations. It would have been nice to see both the black that partially encircles the eye-ring and the well-defined back streaks mentioned as features separating Oaxaca Sparrow (Aimophila notosticta) from Rufous- crowned and Rusty sparrows (A. ruficeps and A. rufescens); both features are actually depicted on the wrong species. Immature Great Blue Herons (Ardea herodias) will probably be misidentified as Cocoi Herons (A. cocoi) from a combination of the pictures (immature Great Blue not depicted) and the text (“from [Cocoi Heron] by white cap…”). Anyone relying on this guide to identify a King Rail (Rallus elegans tenuirostris) in central Mexico will probably not be satisfied with the information provided. It is unfortunate that the yellow or red underwings of flickers (Colaptes spp.) are not mentioned or illustrated; nor are the black undertail coverts that are the main difference between male Broad-billed and Doubleday's hummingbirds (Cynanthus latirostris and C. l. doubledayi). The illustrations of Rufous Mourner (Rhytipterna holerythra) and Rufous Piha (Lipaugus unirufus) do not reflect the 20% size difference between them and, in error, their lengths are given as the same (25 cm).

Well-marked subspecies are treated in this as in most other guides to the region (but important omissions here are Lampornis amethystinus margaritae, Automolus ochrolaemus cervinigularis, Mionectes oleagineus assimilis, and Salpinctes obsoletus fasciatus); yet, as in other guides, insufficient warning is made that because subspecies featured are often only a sample, subspecific identification based on the guide remains tentative, and a taxonomist may identify a bird as belonging to a subspecies not mentioned in the guide.

The range maps in van Perlo's guide use a clever system of symbols and hatching to concisely indicate relative abundance and seasonal status as well as distribution. Unfortunately, the hatching that indicates “frequent to uncommon resident” can often be confused with bodies of water; see, for example, the maps of Mexican Parrotlet (Forpus cyanopigius) and Prong-billed Barbet (Semnornis frantzii). The outlines of distribution are largely based on maps from  www.natureserve.org (which for most of this region are based on maps in Howell and Webb 1995). They are therefore quite accurate but contain many of the same omissions. Much new data published in the past 10 years (e.g., in North American Birds) has expanded our understanding of species distributions. The range map of Green Parakeet (Aratinga holochlora) erroneously includes the range of Red-throated Parakeet (A. rubritorquis), though the latter is treated in the guide as a distinct species. The treatment of Amazona ochrocephala and A. oratrix is also confusing.

Overall, I recommend this guide to anyone who needs a portable book for identifying most birds in this region. The compactness that is its main strength, however, is not without its disadvantages. The font is very small; I have no trouble reading it, but I may in 10 years. Any increase in font size would be appreciated. Making the pages 1 cm wider or adding 50 or so extra pages, or both, to accomplish this—and to enhance text helpfulness, particularly with difficult cases such as Empidonax flycatchers—would still leave this guide conveniently compact. The flaws I have mentioned can be fixed quite easily. I very much look forward to a second edition of this guide.