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The ivory-billed woodpecker – an American icon among birds (Image: John A Ruthven)

The apparent rediscovery of the ivory-billed woodpecker in 2005 – hailed as one of the great conservation triumphs of recent times – may be merely a case of mistaken identity, according to a new study.

In April 2005, researchers led by John Fitzpatrick at the Cornell Laboratory of Ornithology in Ithaca, New York, announced in the journal Science that the woodpecker, believed extinct for 60 years, had been seen alive in the swamps of eastern Arkansas, US. And they had a video of the bird to back their story.

The bird's seemingly miraculous survival for many decades caused a stir among conservationists worldwide, and the US government moved quickly to appoint a recovery team and commit more than $10 million to try to rescue the species.

But as the first frenzy of excitement subsides, many ornithologists are now coming forward to say they are not convinced by the evidence behind the supposed rediscovery.

"When I first heard the news, I was really excited," says Michael Patten, director of research at the University of Oklahoma's Sutton Avian Research Center in Bartlesville, US. "I went right to Science's website, and I was crestfallen. I was like, ‘Oh, my God. This is all they have’. I wanted them to be right, but it was pretty apparent right away that they sure don't have much here."

Frame by frame

The problem is that the video – still the best evidence of the woodpecker's existence – contains no more than a blurry, four-and-a-half-second glimpse of a distant bird as it takes off from a tree and flies away into the forest. See the video here (.mov format).

Fitzpatrick's team has painstakingly examined the footage frame by frame, and they remain convinced it shows enough detail to prove that the bird is an ivory-billed woodpecker and not a pileated woodpecker, the only other woodpecker of similar size and appearance.

In particular, the researchers point to the pattern of white markings on the wings and body, the size of the bird and shape of its wings, and its rapid wingbeats. (See the detailed analysis.)

Flashes of white

But sceptics challenge the Cornell team's interpretations on each of these points. A pileated woodpecker – either a normal one or a rare piebald form with more white feathers showing – could have shown similar flashes of white in flight, says Jerome Jackson, an ornithologist at Florida Gulf Coast University in Fort Myers, US, and one of the world's leading experts on the ivory-billed woodpecker.

And the ivory-billed woodpecker is only a few centimetres larger than the pileated one, he says. "That's about the difference between a yardstick and a metre stick," Jackson notes. "At 100 yards, could you tell the difference between a yardstick and a metre stick? It just doesn't make sense to say it was much larger than a pileated woodpecker." Jackson published his criticisms in January in the ornithological journal The Auk (vol 123, p 1).

But if there really are ivory-billed woodpeckers in the Arkansas woods, critics say, should searchers not have seen another by now? "They might not be visible on two or three trips or 50 hours of observation," says Jackson. "But now we're talking about thousands of hours by the Cornell people alone. In my opinion, we should have had something by now."

Journal reference: The Auk (vol 123, p 1)