Caught on tape: an ivory-billed imposter?

CHICAGO, March 15 (Reuters) - Fresh analysis published on Thursday suggests that a fuzzy four-second video that revived hope the rare ivory-billed woodpecker had survived extinction may be nothing more than a case of mistaken identity.

Research published in the journal BMC Biology compares footage of the common pileated woodpecker with a now-famed video shot in 2004 by David Luneau in the swamps of Arkansas of what he believed to be an ivory-billed woodpecker.

Before that, there had been no confirmed sightings of ivory-bills for half a century.

Luneau's finding, which appeared in the journal Science in 2005, has been disputed by several bird experts. A new study by J. Martin Collinson of the University of Aberdeen in Britain raises even more questions.

The study compared Luneau's video with footage of the pileated woodpecker, a similar, large but common species that is also black and white with a dramatic red head.

Collinson analyzed the flight and plumage patterns of the bird in the Luneau video.

One argument had been that the pileated woodpecker's wings beat more slowly than the 8.6 beats per second captured in the Luneau video. But Collinson noted that the pileated's wings have been known to reach 8.6 beats in an escape flight.

He also asserts that the black edges of the pileated woodpecker's distinctive trailing wings show up in Luneau's video as the wings stroke downward. The trailing edges of the ivory-billed woodpecker's wings are white.

Based on these observations, he thinks the ivory-billed woodpecker's survival remains unproven.