The ivory-billed woodpecker, if you haven' t heard, is no longer extinct. In late spring,

a group of 17 researchers announced in the online version of Science that they had spotted at least one member of this majestic species living in the cypress and tupelo swamps of eastern Arkansas. Once found everywhere in Southern hardwood forests, the ivory-billed woodpecker tumbled in population after the turn of the century, the victim of avid collectors and logging. It had last been seen in 1944, reduced to what Tim Gallagher, author of "The Grail Bird: Hot on the Trail of the Ivory-Billed Woodpecker," calls "a symbol of everything that has gone wrong with our relationship to the environment."

"The Grail Bird" is the story of this remarkable rediscovery, told by one of the chief rediscoverers. The editor of Living Bird magazine, Gallagher began the book several years ago with milder ambitions. The plan was to interview anyone who had seen the bird -- or thought he or she had. Soon, though, he was swept into a web of tantalizing rumors and half-clues, propelled by the possibility that a living ivory-bill might yet be found. "If someone……could prove that this remarkable species still exists, it would be the most hopeful event imaginable: we would have one final chance to get it right, to save this bird and the bottomland swamp forests it needs to urvive." Hope was a thing with a three-foot wingspan.

"The Grail Bird" is less an ecological study than a portrait of human obsession; if not for the outcome, it could as easily be a book about the hunt for Bigfoot. Gallagher stakes out swamps teeming with alligators and cottonmouths. He sifts through shady evidence, from fuzzy Instamatic photographs to bags of bark shavings -- peeled, possibly, by the ivory-billed woodpecker in its search for beetle grubs. He suffers bloodied feet and an infected knee. His closest companion, Bobby Ray Harrison, a wildlife photographer and an arts professor at Oakwood College, dresses in full camouflage gear and canoes with a camcorder attached to his helmet. Sasquatch chasers," Gallagher' s wife calls them. Yet for all the shenanigans, his book is an insightful look at what most biological fieldwork involves: a lot of sweating, sitting and waiting for ghosts to -- maybe -- make themselves real.

As tales go, "The Grail Bird" isn't the most stylishly told. Gallagher lets his characters talk at too-great length, and the incidental details are sometimes overly incidental. ("After pigging out on bad burgers, we got a room at a cheap motel and quickly fell into a deep, exhausted sleep with lots of snoring.") But most readers probably won' t mind. As some rivers are to be enjoyed not for the quality of the water but for the quality of the stones to be found therein, so it is with some books. Gallagher presents a series of lively characters: Fielding Lewis, a former Louisiana state boxing commissioner who in 1971 took two fuzzy photographs of the wood pecker that were subsequently -- and perhaps mistakenly -- discredited; an anonymous "woodpecker whisperer" who claims to have a telepathic connection to the birds, even a thousand miles away. (One group of searchers failed, they were told, because they were noisily scaring off the bird.)

Oddly missing from this recounting is any extended focus on the ivory-billed woodpecker itself. Granted, the bird has been invisible for decades, a presence notable largely for its absence. Still, the book might have given us the animal' s history in more detail -- something to convey the visceral appeal of this "grail." Without that, the quest -- though triumphant -- at times feels hollow, and the fulfillment of the author' s obsession veers perilously close to sounding like an end in itself.

According to the text, the ivory-billed woodpecker ______.

A．is extinct since the year of 1994

B．was found by a group of 17 researchers through the internet

C．is called "Grail Bird" because it is hallowed to the degree of holiness

D．is so famous that it has become a symbol of the spoiled relationship between human beings and nature