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In a kind of he-said-she-said squareoff in Science today David Sibley et.al. have advanced their critique of the Arkansas Ivory-bill claims, followed immediately by a rebuttal from Cornell:
http://www.sciencemag.org/cgi/content/full/311/5767/1555a
http://www.sciencemag.org/cgi/content/full/311/5767/1555b
Both are short and I suppose worth reading although this material has basically already been covered elsewhere by now and some folks will simply get bogged down in the minutia of the arguments at this point. As I suspected might be the case, the Sibley piece is entirely a critique of the Luneau video, and even at that, basically just focusses on the initial perched white wing pattern and the black-white pattern in flight -- with only slight mention of the wingbeat or size analysis. And as Cornell notes, Sibley misrepresents the amount of white in the Pileated underwing in his own field guide depiction. There is little critique of the acoustic data or the 7-16 sightings originally reported which are really the core of Cornell's evidence (the video is just an adjunct; almost an afterthought they worked with when they were unable to obtain better film). As I've said before someone must make the case that 7 credible knowledgeable individuals are either dishonest or incompetent to truly knock down Cornell's evidence; probablistically 1 or 2 or 3 people erring may happen but as you increase the number to 4, 5, 6, 7 - 16 independent sightings, the probability rapidly declines. (Similarly, no one ever successfully challenged the credibility of David Kulivan in 1999 and his closer, lengthier sighting. Lack of confirmation does not imply refutation.) And this doesn't even take into account the long history of other credible sightings that have never been disproved. (Maybe there is one, but I know of no other bird that has ever had such a history of claims but was nonetheless regarded by so many as extinct.)
Like so many of the skeptics Sibley et.al. try to give themselves an out toward the end by stating, "Ivory-billed woodpeckers may persist in the southern United States, and we believe that conservation efforts on their behalf should continue..." -- if the bird is found this will allow them to wriggle and say that they never claimed the bird was extinct, only that they wanted to see better evidence. Maybe... but under the circumstances, it sounds a bit disingenuous, considering the harm their criticism may beget.Their time would have been better spent in the field looking for the species rather than analyzing a single video and creating a lot of sound and fury signifying little.
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3 comments:
Cyberthrush:
David Sibley did a pretty damn good job of convincing me that the bird in the Luneau video is a Pileated Woodpecker. I waivered back and forth on the Luneau video several times based on comments I read in here or other places in the last year. In my blog a month or so ago I looked at the video frame by frame and mention that bird in the video was indeed a Pileated Woodpecker. Then Bill Pulliam pulled me back in telling me that the black edges you see on the white underwing linings is also present on other white or bright objects ( his hand on the paddle has black edges around it ) So I waivered back on thinking the woodpecker is indeed a IBWO based on listening to Bill and reading Cornell's paper.
After seeing David Sibley's illustration next to the frames I feel fairly certain that the bird in the Luneau video is a Pileated Woodpecker.
I am certain that this will not quiet those at the Ornithology Lab at Cornell and the debate will heat up again. Personally I wish this whole woodpecker ordeal will just end. Let the searchers search for the woodpecker in peace like they been doing before Cornell got involve in 2004. Some day or maybe soon a photo will be taken to prove once and for all the IBWO lives. Right now the bird in the Luneau video lost a lot of credibility and I believe many birders are going to agree with David Sibley's article.
The video is important--there would have been no paper in Science and no hoopla without the video. Sibley et al. have basically the same interpretation of the video that I did here on December 20, 2005. I doubt they were reading my material--I think they came up with the same analysis independently. That is possibly because it is correct.
The sight records are important too. I maintain some hope based on those, but I think it is possible they got glimpses of a leucistic bird, or one that had molted some primaries, as shown here.
I'm afraid those two things could explain the whole flap in Arkansas. I still hold out some hope for other areas, and I hope people continue looking systematically.
If that bird was committing a crime, it would've been easily convicted on the eyewitness testimony alone. Those are some very credible witnesses.
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