Debate Over Ivory-Billed Woodpecker

Debate continues over the video presented last year in support of reported sightings of the ivory-billed woodpecker, a bird thought to be extinct, in the Big Woods of Arkansas (Science 3 June 2005 308: 1460-1462). In a peer-reviewed "Technical Comment," David Sibley and his coauthors argue that reanalysis of the video taken in April 2004 indicates that the bird in the video is a normal pileated woodpecker. They claim that the original research team misinterpreted the posture of the bird in flight and at rest, and thus misinterpreted its size and plumage pattern. They hold that the extensive white visible during flight can be accounted for by the underside of the pileated's wings, and that other aspects of the wing pattern are inconsistent with ivory-billed woodpeckers. Sibley and colleagues find that the quality of the video is not good enough to clearly see white stripes along the bird's back that are characteristic of ivory-billed woodpecker. And they do not believe that the available comparative data on wingspan and flight style are sufficient to distinguish between the two woodpecker species.

In their "Technical Response," John Fitzpatrick and his coauthors dispute these reinterpretations of the video and stand by their original conclusion that the bird is an ivory-billed woodpecker. They argue that their interpretation of the bird's launch posture is more accurate than of the alternative offered by Sibley and colleagues and thus that their previous calculations of the extent of white plumage are supported. They also note that the angle of view in the video shows white plumage on the upper surface of the wings that is unlike the pattern in pileated woodpecker and that the black trailing edge on the underwing characteristic of the pileated is "consistently absent" in the video. Fitzpatrick and colleagues detect longitudinal white stripes on the bird's back in several video frames, and they conclude that available data on wingspan and flight style also point toward the bird being an ivory-billed woodpecker.

Despite their conflicting interpretations of the video, both sets of authors, whose writings appear in the 17 March 2006 issue of the journal Science, agree on the need to continue conservation efforts that would benefit the ivory-billed woodpecker.

Becky Ham

16 March 2006