ITHACA, N.Y. -- On April 25, 2004, University of Arkansasresearcher David Luneau accidentally kept a video camera running as hiscanoe drifted through a bayou in the Big Woods of Arkansas -- andrecorded an ivory-billed woodpecker.
The video, blurry becausethe recorder was on auto focus, was the main piece of evidence featuredonline in an April 25 Science Express paper claiming the rediscovery ofthe woodpecker, once thought to be extinct.
While skeptics haverefuted the video, claiming that it shows a pileated woodpecker,Cornell University researchers are standing firmly by the video asevidence of the existence of the ivory-billed woodpecker.
KenRosenberg, director of the Cornell Lab of Ornithology's ConservationScience Program, offered a frame-by-frame analysis of Luneau's video atthe American Ornithologists' Union Meeting at the University ofCalifornia-Santa Barbara, Aug. 24.
Rosenberg reviewed theresearchers' rationale for claiming that the video captured anivory-billed woodpecker. Though blurry, the video shows the bird'soutlines and black and white coloring, he said.
The maindifference between ivory-billed and pileated woodpeckers is in theplacement of the black and white coloring, especially on the wings, andaccounts for why an untrained eye may easily mistake a pileated for anivory-billed woodpecker.
On an ivory-billed woodpecker, whitefeathers run along the trailing back edges of its spread wings, whileblack feathers trail along a pileated woodpecker's wings, from thebird's body all the way to its wing tips. Rosenberg showed frames fromthe Luneau video, indicating that only white feathers were visiblealong the broad trailing edge of both the underwing and upperwing.
To show the differences, the video frames were compared with blurry frames of pileated woodpeckers.
Also,using models of ivory-billed woodpeckers, scenes were reenacted with anout-of-focus camera, revealing a striking similarity to the actualvideo. Frames from a video of a pileated woodpecker model were shownfor comparison.
Other evidence is that in one segment of theLuneau video, a large bird partially peeks out from behind a treetrunk, showing a portion of its white wing. Researchers from the Lab ofOrnithology placed a stuffed ivory-billed woodpecker on the actual treewhere the video was shot to show that the white corresponds to thewhite outer wing of the perched bird. Still, skeptics claimed thiscould be the underwing of a pileated woodpecker extending from behindthe trunk and revealing white feathers.
To counter this claim,Lab of Ornithology members in Arkansas physically measured the treetrunk that appeared in the video, Rosenberg explained. They alsomeasured a roosting cavity from a 1935 photo of an ivory-bill. Usingthe actual tree trunk and cavity, which the lab has in its possession,the researchers were able to take the relative measurements from theimages and make absolute measurements of the bird's wings.
Whilethe distance from the pileated woodpecker's wrist (part of the ulna,one of the wing bones) to tail-tip measures 29 centimeters (11.4inches) on average, the wrist-to-tail tip distance in the video reachesa full 35 centimeters (13.8 inches), which is in the upper range forivory-bills. The size of the wing ruled out that the frames were of apileated woodpecker, Rosenberg said.
When one audience memberasked about sightings of pileated woodpeckers with extra white on theirwings, Rosenberg said that he and his colleagues were aware of moltingpileated woodpeckers that lose some of their black feathers, revealingmore white. But, he added, he has never heard of such molting occurringsymmetrically, as the wings in the Luneau video appear.
"We think the body of evidence confirms the presence of at least one ivory-billed woodpecker," said Rosenberg.
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