ITHACA, N.Y. -- Until recently, the ivory-billed woodpecker was like Bigfoot or the Loch Ness monster -- a famed creature that for years eyewitnesses claimed to see but that science could not substantiate. 

This impression runs through "The Grail Bird" (Houghton Mifflin, 2005), a new book by Tim Gallagher, an editor at the Lab of Ornithology at Cornell University who played a primary role in the rediscovery of the ivory-billed woodpecker, once considered extinct. For years, people claimed to have heard the bird's distinct "kent, kent, kent" call and the powerful loud-then-softer double rap of its bill. Some asserted they had witnessed fly-bys of the large crested, black-and-white, white-billed woodpecker.

But when it comes to cryptozoology -- the search for and study of animals that are only rumored to exist -- any claim requires strong proof. And the scientific establishment met the smattering of sightings with skepticism. 

John Dennis, an ornithologist and popular author of bird books, took the last scientifically accepted photographs of the elusive woodpecker in Cuba in 1948. The bird had seemingly vanished even earlier in the United States as habitat destruction and collecting took their toll. 

But last month, the Lab of Ornithology and The Nature Conservancy announced to the world that they had video footage of the woodpecker taken in 2004. Gallagher's book covers the 60 years between the last confirmed U.S. sighting in 1944 and the aftermath of the author's own sighting of the bird in Arkansas in early 2004 that led to the final proof. 

Gallagher writes: "My goal was to find as many people as possible who had taken part in these searches and sightings, and if the sightings seemed credible, to follow up on them myself." While engaging the reader in his mission, Gallagher immerses himself into the culture of those who have passionately chased the ivory-bill. 

He tells how in 1966, in pursuit of an ivory-bill, Dennis plunged naked into chilly black bayou water in east Texas to get a full view of the woodpecker. Despite Dennis' familiarity with the bird, ornithologists "laughed at" his report, Gallagher notes. 

A similar fate awaited George Lowery, head of the Museum of Natural Science at Louisiana State University (LSU), when he showed two somewhat blurry snapshots of an ivory-bill at a 1971 ornithology meeting. "These were shot with a cheap Kodak Instamatic camera and have some of the typical Bigfoot/Loch Ness monster fuzziness," Gallagher writes. In each picture, a bird sat on a different tree but had the same stiff posture, and the bill was hidden. 

People claimed the bird was a carved decoy or a taxidermic mount. But behind closed doors, some believed the pictures were real. 

"Woodpeckers -- bark-foraging birds in general -- have pretty much a single posture," said James Van Remsen, curator of birds at LSU's Museum of Natural Science, in a 2004 conversation with Gallagher. When Gallagher found the man who took the photos, a cigar- chomping septuagenarian named Fielding Lewis, Gallagher thoroughly believed him. 

Still, Lowery was ridiculed. 

When David Kulivan, an undergraduate at LSU sighted two ivory-bills in 1999 in a Louisiana Wildlife Management Area, even hardened skeptics believed his account. Still, Van Remsen warned Kulivan, "If you go public with this, a lot of people will put you in the same category as those who claim to have seen UFOs and Bigfoot." 

When Kulivan talked publicly of his sighting, search teams scoured the area, including a team of bioacoustic experts from Cornell's Lab of Ornithology, but they never found an ivory-bill. Gallagher phoned Kulivan in 2004 but received "an instant chill" from the young man. Kulivan responded, "I've decided -- and I've been advised -- not to talk about this anymore." 

On Feb. 27, 2004, Gallagher and his close friend Bobby Harrison of Alabama's Oakwood College paddled through a bayou in northeastern Arkansas with Gene Sparling, a kayaker who just two weeks earlier claimed to have witnessed the legendary bird there. As Sparling paddled far ahead, an unmistakable ivory-billed woodpecker flew past in front of their canoe at close range. The experience was life-altering, said Gallagher, but he was immediately concerned with how to best divulge the discovery. 

"A lot of good people have been ruined because they claimed they saw an ivory-bill," he said. Gallagher and the others decided to keep quiet about the sighting for now, in part to avoid attracting hordes of amateur birds descending on the Arkansas bayou. 

In a series of closed-door meetings, Gallagher revealed his secret to colleagues at Cornell. In the months ahead, teams of bird experts, including many from the lab, took turns combing the Arkansas area by canoe. With no woodpecker in sight, Gallagher joked to a colleague: "I feel like I'm really hanging out alone on a limb with the Sasquatch chasers and Elvis sighters." 

Eventually, the scouts caught a few sightings, and University of Arkansas professor David Luneau finally captured the mystery bird on videotape April 25, 2004. 

Gallagher ends his book by commenting that scientists should approach questions and data with open, dispassionate minds, but "this has been anything but the case with the ivory-billed woodpecker for almost a century." 

Perhaps, finding the ivory-bill will offer some consolation for those who are still chasing Bigfoot and the Loch Ness monster.