A bird field guide is usually about distinguishing one pretty feather from another. The new "Smithsonian Field Guide to the Birds of North America" is that and much more — it's a manifesto loaded with political and cultural baggage.

The field guide, by Ted Floyd, the editor of Birding magazine, clearly will help birders identify the most common birds on the continent. More subtly and controversially, says its author, it's an attempt to restore the popular hobby of bird-watching to a scientific mind-set.

Handout (ENLARGE)

The field guide identifies the most common birds in North America.

Smithsonian Field Guide to Birds (ENLARGE)

The golden-winged warbler is being 'genetically swamped' by breeding with the hardier blue-winged warbler.

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The practical first.

Designed to attract what Floyd calls "the eager nature lover," the new guide covers 730 species and includes 2,500 stunningly vivid photographs, the bulk of them by Brian E. Small.

To field-test the Smithsonian guide, the AJC enlisted a local expert, Gordon McWilliams of Decatur. McWilliams keeps an impressive life-list of birds he's seen, leads Audubon Society walks and sometimes plans his vacations by studying bird-migration maps.

Over a recent weekend in South Carolina, he spotted 41 species, checking his binoculars' view against the images in the Smithsonian guide. His verdict: It's the best beginner's birding guide on the market.

"The photos are better than in other field guides, and the layout [makes it] easy to locate birds, especially for a novice," McWilliams says. His only gripe: "I just wish the book's size was smaller so it could fit in the pocket."

He says he's not ready to shelve his copy of "The Sibley Guide to Birds" (Knopf, 2000) — the favorite of advanced birders, where each species is abstracted in exquisitely detailed drawings — but he likes the Smithsonian as a serious supplement. He's already recommended it to friends in hopes of building their interest in birding.

'The Peterson Eraser'

Then there's the new guide's more controversial aspect.

To appreciate it, you have to go back almost 75 years to a popular book that foreshadowed a defining cultural trend of our time: the radical idea of self-empowerment in a specialized world, where you are the expert.

It's a notion that touches a widening web of lives today, from do-it-yourself hardware stores to the free (often reckless) flow of news and commentary on the Internet.

The book was Roger Tory Peterson's 1934 "A Field Guide to the Birds," which fueled a boom in U.S. bird-watching and raised awareness of our damaged environment.

As a side effect, however, Peterson's approach has helped perpetuate an anti-science mind-set, says Floyd, who's pursued colorful wings in Georgia and around the country.

"Peterson is one of the major American thinkers of the 20th century," argues Floyd. Without invoking religion in any way, "he did more than anyone of his time to undermine Darwin and evolution. His guide suggests that species are permanent and fixed, in essence a biblical view, and his mind-set has taken hold among birders."

Peterson's system, which has become the standard in birding, relies on simplified drawings with emphasis on "field marks," key indicators that help distinguish one species from another.

A chipping sparrow is a drab little brown bird, but look closely and you'll see its unique rust-colored cap, the white line above its eye and black line through the eye — all the data you need for a positive ID at your backyard feeder.

Floyd calls this method "the Peterson Eraser."

"[Peterson] taught us to ignore subtle variations in plumage and behavior — all the accumulated messiness and fuzz that we find in nature and which, in fact, is what Darwin's natural selection is all about, confirmed by molecular and genetic studies."

Restoring the fuzz

With the Smithsonian guide's photos of actual, imperfect individuals in native settings, Floyd hopes to restore a little of the fuzz — the beautiful messiness of birding in close-up — and thereby help shift our attitudes while still allowing for quick identification.

The American dipper, for instance, is commonly found along fast-flowing streams; it gets a clear "portrait" picture plus an unforgettable "dipping" shot, a ballet maneuver over an icy stream.

Where species blur and hybridize, the new guide is in its element. The golden-winged warbler, a tiny fluff of gray and black feathers with a yellow smudge on its sides and a lemony crown, is gradually being "genetically swamped" as it cross-breeds with the heartier blue-winged warbler.

Both these birds, and their intermediate hybrids, migrate through Georgia in early spring, although sightings of the golden-winged are increasingly, alarmingly uncommon. A warning captions one of the hybrid pictures: "Many cannot be assigned to a tidy category." It's like a flashing highway sign: Evolution at Work.

Tucked in the back of the new Smithsonian guide is a disc of downloadable MP3 bird vocalizations — a first for a major field guide.

Often the difference between a novice and skilled birder is the latter's ability to first recognize a distinct song, then know what to look for in the trees. With just 138 common species on the disc, however, it's nowhere close to definitive for North America.

Again, Floyd says, he had the new birder in mind in limiting the number of digital songs, squawks and calls.

As with the rest of the book, he says, his hope is to "empower but not overwhelm the entry-level user, within the bounds of a 'whole bird' attitude."

FINDING BIRDS (and the people who look for them)

Around Atlanta and beyond, there are resources for both veteran and would-be birders. Among them:

• www.atlantaaudubon.org: Home of the nonprofit, 36-year-old Atlanta Audubon Society, it offers news and information about local birding events, reports on rare-bird sightings and even a link on where to buy shade-grown, bird-friendly coffee around metro Atlanta.

• www.gos.org/gabo.html: Georgia Birders Online (GABO) is an e-mailed listserv on all matters birdy. Sign on, subscribe and join in.

• www.birdingadventuresinc.com: An audio guide to 143 species, "Bird Songs of Georgia" by Atlanta birder Georgann Schmalz (four CDs, $35) is an excellent tool for learning by ear.

Top summertime birding sites

• Newman Wetlands Center and E. L. Huie Facility: Atlanta Audubon describes the Clayton County Water Authority's marsh and giant ponds as "the metro area's singular best all-around birding area" and great for shorebirds and waterfowl. 2755 Freeman Road, Hampton, about 10 miles south of I-285. Wetlands Center info: 770-603-5606.

• Chattahoochee River National Recreation Area's Cochran Shoals: Fine birding along the west bank of the Hooch, as long as joggers and cyclists don't clog the boardwalk and river paths. Parking lot is where Interstate North Parkway crosses the river.

• Fernbank Forest: Behind Fernbank Science Center, it's 65 acres of mostly uncut forest, hosting six species of woodpeckers and with a few oaks 225 years old. 156 Heaton Park Drive, Atlanta. 678-874-7102, fsc.fernbank.edu