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15 March 2007 (All day)
New evidence casts more doubt on the claim that a bird long thought extinct is still alive and flapping. In 2005, the birding world was riveted by a report that the majestic ivory-billed woodpecker (Campephilus principalis) had been definitively spotted in Arkansas (ScienceNOW, 28 April 2005). Since then, some scientists have voiced doubts about the strength of the evidence. Now a video suggests that the re-discoverers may have mistaken a large, common woodpecker for the ivory-billed.
The original report of the ivory-billed woodpecker (Science, 3 June 2005, p. 1460) was based on three lines of evidence. First, a grainy, 4-second video filmed by electrical engineer David Luneau of the University of Arkansas in Little Rock showed a bird resembling an ivory-billed woodpecker as it flew from a tree in the Cache River National Wildlife Refuge in eastern Arkansas. Second, several experienced volunteers reported sightings of a similar bird. And finally, acoustical recorders placed in the area by the research team, led by John Fitzpatrick of the Cornell Lab of Ornithology in Ithaca, New York, caught cries and knocking noises like those made by ivory-billed woodpeckers.
Skeptics were not convinced by the video. In a technical comment last year, David Sibley of Concord, Massachusetts, and three scientists argued that the depicted bird could have been a pileated woodpecker (Science, 17 March 2006, p. 1555). Sibley, an author of bird identification books, noted that the trailing edge of the bird's wings was black, as in a pileated woodpecker. If the bird were an ivory-billed woodpecker, this edge should have been white. The Cornell team countered that the black coloring was in fact part of the background, and that video does show white wings with white trailing edges. What's more, Fitzpatrick pointed out that the bird in the Luneau video beat its wings 8.6 times a second, faster than is known for pileated woodpeckers.
Now, there's new video evidence. Taken by amateur birder David Nolin, the grainy films capture pileated woodpeckers flying away from the camera, much like in the ivory-billed video. When J. Martin Collinson, a human geneticist and avid birder at Aberdeen University in the United Kingdom, analyzed the videos, he found that some frames showed wings with no black trailing edge (see photo). "The pileated woodpecker can produce wing patterns that look more like what you'd expect from an ivory-billed," he concludes. "I'm quite convinced that the bird in the Luneau video is a pileated woodpecker." In addition, one of the pileateds beats its wings as fast the bird in the Luneau video, Collinson reports today in BMC Biology.
Sibley says the new paper backs his argument: "He's documenting for the fist time how ivory-billed-like a pileated can be." But Fitzpatrick disagrees. He points out that the pileated woodpecker in Nolin's video quickly slows its wingbeats, as pileated woodpeckers are known to do. The bird in the Luneau video, in contrast, continues to fly rapidly for all 4 seconds. As for the plumage, he says that the Nolin video was not properly processed for frame-by-frame analysis. "The result is a blur and confusing to decide where the black and white are," he says.
Who's right? That's a hard call to make--and probably will remain so without clearer evidence to analyze. "A good photo or video would end this debate tomorrow," Collinson says.