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Ivory-billed Woodpecker Debate Heats Up
Last June researchers triumphantly announced the rediscovery of the ivory-billed woodpecker, thought extinct for nearly 60 years.
But another group of ornithologists said a video used to identify the bird was too fuzzy and that plumage color patterns don't rule out the bird being a common pileated woodpecker.
The original group has reanalyzed the video, recreated test conditions with painted models, and feels confident with their original identification. They especially oppose the idea of the bird being a pileated woodpecker.
The debate continues with a presentation from both sides in the March 17 issue of the journal Science.
Background
The ivory-billed woodpecker is, or was, one of the largest woodpeckers in the United States, measuring about 20 inches long and weighing a little over one pound. Its plumage is characterized by white trailing feathers on both the underside and topside of the wings. And, of course, it has, or had, a distinctive ivory-colored bill.
The last confirmed sighting of an ivory-billed woodpecker was in Louisiana in 1940.
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Since then, glimpses of the similarly sized, but common, pileated woodpecker have often been identified as the ivory-billed but later disproved. Pileated woodpeckers are similar in coloring, except their wings are mostly black on top with white lines in the middle, and white with black trimming on the underside. They also have black bills.
In 2004, David Luneau of the University of Arkansas caught a woodpecker on video in the Big Woods of Arkansas. Analysis of the tape by Luneau, John Fitzpatrick of Cornell University, and other researchers indicated that the bird was an ivory-billed woodpecker, and they published their finding in June of 2005.
"From the very beginning we've stated the null hypothesis is that it's a pileated. We've tried to accept the null hypothesis, but we just can't," Fitzpatrick said. "To me, the evidence is overwhelming that it is [an ivory-billed]. That video is not a pileated woodpecker."
Round 1: Wing tips
The group's explanation did not totally convince David Sibley, an accomplished bird identifier and illustrator. The main sticking point is wing color patterns, which are difficult to identify due to the poor quality of the original video. Sibley and his colleagues went over the video frame by frame.
"Our interpretation is reasonable and consistent with a pileated woodpecker," Sibley told LiveScience. "You can't rule pileated out, and therefore you can't say that it's an ivory-billed."
After launching from the tree, the bird rapidly pumps its wings to gain altitude and fly away, providing a decent view of both the undersides of its wings and the trailing edge.
"There's a black patch on the wingtip as it's flying away, but it should be all white on an ivory-billed woodpecker," Sibley said. "The pattern of black and white just doesn't match what ivory-billed woodpeckers should show and does match what a pileated shows."
The rear view of the bird as it flies away, Sibley said, doesn't show as much white as an ivory-billed should, and the white that is present could be due to blurring. Regardless, he believes this is another point won for pileated.
Since the 2005 publication, Fitzpatrick has analyzed 70 videos of pileated woodpeckers flying away and hasn't observed nearly as much white in the wings as he sees in the Luneau video.
"In every single video, pileated shows unambiguously black borders to the wings as it flies away," Fitzpatrick said. "The Luneau video does not."
But Sibley didn't spot the telltale black line that should run down the otherwise white wing of an ivory-billed woodpecker.
Fitzpatrick's group was also concerned about the missing stripe, so they recreated the conditions. They went to the same spot on a cloudy day with the same camera and models of both woodpeckers with their wings outstretched.
They found that with the blurriness and quality of the tape, the white of an ivory-billed's wing would obscure the black stripe. Their test also showed that a pileated's wing would have a lot more black on it than what shows in the video.
"The video shows white tipped with black, exactly what we reproduced with a model ivory-billed wing," Fitzpatrick said.
Sibley says he doesn't trust that the color patterns of a flying and flexible bird can't compare to a stiff, non-moving model. Fitzpatrick admits that the conditions are not ideal.
"What you can say, though, is that we produced images much more consistent with ivory-billed than with pileated," Fitzpatrick said.
Also, the rate at which the specimen flapped its wings is faster than what's expected of a pileated.
"The video shows 8.6 wing beats per second, and no pileated flaps that fast," Fitzpatrick said. "That is not how pileateds take off from a tree."
Round 2: Launching point
At the beginning of the video, all that can be seen of the bird is a spot of black with a long white sliver below it. This view is consistent with the topside of an ivory-billed woodpecker's wing if it were folded up, Fitzpatrick's group said.
Sibley's group, however, believed there was too much white in that video frame, and what they were seeing was actually the underside of the wing as it flapped furiously to escape Luneau's canoe.
Sibley believes that the black trailing feathers of the underside of a pileated's wing are visible in this view, which Fitzpatrick takes exception to.
"If that was the underside of a pileated wing, that black at the top would remit all the way down the side," Fitzpatrick told LiveScience. "There's no ambiguity when you see [a pileated] with a wing open—it's jet black. And it's not trivial, there's more black than there is white on the underside of a pileated's wings."
Furthermore, Fitzpatrick said, the takeoff hypothesized by Sibley would be a very awkward posture for a woodpecker. Sibley countered by saying that it would use this atypical launch style to flee quickly.
Round 3 up next?
So what comes next in the debate over this fuzzy video?
Sibley said he would like to see a third party review the tape and bring another perspective. Both sides agree they have spent enough time analyzing video and should instead focus on mounting a conservation effort for the ivory-billed woodpecker in case it does exist.
"We're tired of it. The job is now back in the hands of people who are willing to put in the time and effort to find a breeding pair of ivory-billed woodpeckers," Fitzpatrick said. "I want to pay attention to the future."