According to various estimates, anywhere from 42 million to 60 million Americans consider themselves bird watchers — birders, to use the preferred term among the faithful. These people spend roughly $20 billion a year on items ranging from seed for backyard feeders to high-priced guided tours in pursuit of rare or exotic species. Only two purchases are required, however, to get started: a pair of binoculars and a field guide, i.e., a book illustrating the identifying characteristics of birds encountered in nature. A good field guide is a bird in the hand.
The late Roger Tory Peterson invented this sort of book with his pioneering "A Field Guide to the Birds" (1934), and more than 8 million copies of Peterson's guide and its diverse updatings and amplifications have been sold. Numerous competing volumes have crowded into this commercial niche. Now the birding world is aflutter over the near simultaneous arrival of two more, highly publicized guides: Kenn Kaufman's "Birds of North America" (Houghton Mifflin; 384 pages; $20) and David Allen Sibley's "The Sibley Guide to Birds" (Knopf; 544 pages; $35).
The authors' names alone impart heavy marquee value to knowledgeable birders. Both Kaufman, 46, and Sibley, 39, dropped out of school (Kaufman before the 11th grade, Sibley after a year in college) to study their feathered friends full time, and both quickly achieved legendary status among the reigning experts for their encyclopedic knowledge and their uncanny skill at field identification. But despite their similar backgrounds and levels of expertise, Kaufman and Sibley evidently have very different notions of what a useful field guide should be.
Kaufman aims his book at beginning birders, those who may have trouble telling a hawk from a handsaw. While other helpful guides are targeted toward neophytes, Kaufman's comes with a technological breakthrough. Birders have long disagreed over whether field guides should be illustrated with paintings or photographs. Both have inherent disadvantages: artwork invariably distorts, however minutely, the reality it attempts to convey, whereas snapshots may capture an actual bird in an uncharacteristic pose or in unusual light or shadow. In either case the image on the page will differ, perhaps significantly, from the bird in the bush.
Kaufman attempts to resolve this dilemma by presenting photographs that he has digitally edited on a computer, using his vast experience in the field to render each bird image as accurately and typically as possible. The results are regularly clear, colorful and impressive. Those who want a single, near Platonic representation of a particular species should turn to Kaufman first.
Taking a different approach, Sibley's guide is more exhaustive and, at least to new birders, more daunting. Sibley relies on his own often exquisite paintings to illustrate his book, but he is of course aware that individual drawings can misrepresent their subjects. So he offers multiple images of each species. His page on the American robin, for example, presents four drawings of the bird in flight, two as seen from above and two as seen from below. Accompanying these are drawings of a juvenile robin, a regular adult, a "pale adult" and a slightly different form of the bird seen in eastern Canada. Another drawing portrays a group of robins in typical feeding postures on the ground. Beneath the artwork, Sibley presents a detailed description of robins' vocal behavior ("Call varies from a low, mellow pup or a sharp, clucking, often doubled piik to a sharper, rapid, urgent series kli quiquiquiqui koo..."). All this for what is probably the most easily recognized bird in North America.
Sibley's guide is a treasure of valuable information, but it is also, as a result, a pretty heavy and bulky item to carry while prowling for birds. Kaufman's is light and fits easily into pocket or purse, but its compression comes at a cost: The necessity of filling each page to the maximum has produced sometimes uncomfortably small, though sharp, illustrations. Which one should birders buy? The answer for many will probably be both: Kaufman to have in hand for quick reference in the field, with Sibley waiting at home for post-trip analysis. No etymologist would be content to own just one dictionary. Why should birders be any less resourceful?
In their introductory pages, both authors argue that birding is more than a pleasant way to spend time outdoors. Birders, they say, tend to evolve into conservationists, eager to protect the habitats that sustain avian life. They may be preaching to the choir, but their guides should attract some eager new singers.