Birders: Tales of a Tribe, by Mark Cocker (Atlantic Monthly Press, 230 pages, $24).

I have always somehow felt affectionate awe for the genuinely obsessed citizens of the planet -- though not the obviously evil ones. Collectors of very specific obscure objects, musicians who're happy only when playing instruments discarded early in the Baroque period, around-the-world sailors. Of such fanaticisms that I have had some direct contact with, none seems more soul-captivating for its practitioners than identifying and cataloguing sightings -- whether the outsider calls it birding, bird-watching or binoculared insanity. Now comes the most graceful, respectful and technically rich book on that fascination that I have ever run across. Cocker, a well-established British ornithologist, knows his stuff, and his mania. And he writes beautifully. If you're drawn to feathers, you must read this as a treatise of the best of the fancy. If you just like nuttiness, it's a damned fine read.