Last spring, birdwatchers claimed they had proof that the ivory-billed woodpecker, believed to be extinct for 60 years, was still alive. While some birders doubted the bird's identity, others likened it to the discovery of the Holy Grail.
But now fresh doubt has been cast onto the sighting by America's most famous birdwatcher. David Sibley, author of The Sibley Guide to Birds, said he believes the bird on the video is a pileated woodpecker.
"Although we support efforts to find and protect ivory-billed woodpeckers, the video evidence does not demonstrate that the species persists in the United States," said an article published by Mr Sibley and others in yesterday's edition of the magazine Science.
But in the same edition of Science, another team of researchers defend the bird's identification. That team, headed by John Fitzpatrick of Cornell University's Laboratory of Ornithology, say Mr Sibley's analysis was "based on misrepresentations of a pileated's underwing pattern".