Three weeks before the momentous announcement, members of the Cornell team had gathered at the Arkansas Nature Conservancy office in Little Rock to lay out their case. They discussed the seven sightings and showed the video. As good scientists, they listed the positives and negatives of their proof in great and meticulous detail.

After listening to the presentation, White River refuge manager Larry Mallard looked at Martjan Lammertink. "Martjan," he said, "we have a saying around here that you can't be just a little bit pregnant. So tell me: Are we pregnant, or are we not?"

"We're pregnant," Lammertink said.

The question of whether Lammertink had morning sickness or just a case of nerves seemed mysterious enough to most people. What was the big fuss? Was there a bird or wasn't there?

The current controversy can't be understood, nor can proof of the ivorybill's existence be judged—lacking, as it does, a specimen that could be brought back from Arkansas like King Kong from Skull Island—without getting to know the pileated woodpecker, the joker in this game. The big, black-and-white, relatively common bird gives a raucous call that might as well be mocking the thousands of people who have mistaken it for its larger but similar relative. (Since the discovery announcement, the CLO has received nearly 3,000 reports of ivorybills, some from places as unlikely as Vancouver and Vermont.) To the Skeptics, the video and all the sightings can be dismissed as misidentifications of pileateds resulting from eager wishfulness.

David Sibley, a best-selling bird-guide author and expert on identification, initially was elated at the ivorybill news. It was, as he says, "a story that everyone wanted to believe." Soon, though, Sibley took a fresh look at the evidence and realized how little there was. Within weeks of the announcement, he was among a growing group of experts sharing their doubts in private, each having experienced a moment when, as Sibley remembers, "it struck me that that blurry video could be a pileated."

"I realized at the same time," Sibley says, "what that could mean for the credibility of conservation science. This was the biggest ornithology story of the century. It was international front-page news. What if it was wrong?"