Ivory-bill News

Researchers Stand by Ivory-bill Evidence

Renowned birder David Sibley visited the Cornell Lab of Ornithology last year to view David Luneau's April 2004 video of an Ivory-billed Woodpecker, thought to be extinct for 60 years. The four-second video is the cornerstone evidence for the Lab's claim that the ivory-bill is still alive in the southeastern United States.

Sibley, author and illustrator of the best-selling Sibley Guide to Birds, has now challenged the Lab's analysis of the footage, known as the Luneau video, saying the image could be a Pileated Woodpecker, not the ivory-bill. Science magazine published the article by Sibley and colleagues in the March 17 issue, along with a response by Lab director John Fitzpatrick and colleagues.

"It's almost like a gentlemen's disagreement at this point," said Ken Rosenberg, director of Conservation Science at the Lab and a coauthor of the paper refuting Sibley's analysis. "It is fascinating that we could look at this together and have such huge differences in interpretations of what we are seeing."

Comparison of the upper and lower wing patterns of the Ivory-billed Woodpecker (left) and the Pileated Woodpecker.

John Schmitt

The Lab's experts maintain that the pattern of white in the wings and the way the bird flies in the video are entirely consistent with characteristics of an ivory-bill.

In one sequence of video, Sibley and collaborators believe that the white seen on the wings of the bird flying away from the camera shows the patch of white on the underside of a Pileated Woodpecker, and that the wings were twisting in flight, hiding a pileated's mostly black upper side. The Lab's experts counter that the video sequence shows all the classic ivory-bill markings--extensive white on the top side of the bird's wings, black wing tips and no black along the rear edge of the wing. They add that the idea that the wings are twisted in flight contradicts all models and photographic analyses of how birds flap their wings.

"There isn't anything out there that makes us think you can see the underside at all times in the flight," said Rosenberg. "Every single frame is a white-winged bird with a black wing tip."

The Lab's team also commented that the filmed bird flies in a direct, straight manner similar to a pintail duck and characteristic of an ivory-bill, whereas Pileated Woodpeckers flap with an undulating motion.

"One of the most important things is the flight of the bird," Rosenberg said of the video. "That thing barrels off the tree. A pileated does not fly that way."

Although Sibley and colleagues claim the video evidence is not definitive proof, they do not deny that Ivory-billed Woodpeckers may well exist in the Big Woods of Arkansas, where the video was recorded. The experts from both sides of the debate have been committed to the conservation efforts since the woodpecker's rediscovery was announced in April 2005.

The Lab has posted a link to the Science articles and an in-depth analysis of the Luneau video at www.birds.cornell.edu/ivory.

--Krishna Ramanujan, Life Sciences writer, Cornell Chronicle

Hope Raised by Possible Ivory-bill Encounters

In February 2006, the Ivory-billed Woodpecker Recovery team released new details of six possible visual encounters with ivory-bills in the Big Woods of Arkansas, reported by the Cornell Lab of Ornithology's search team, birders, hunters, and refuge employees.

These encounters do not rise to the level of confirmed sightings, which require better documentation. "There is nothing more definitive than anything we've reported previously and we certainly are not claiming any new confirmation of the bird," said Ken Rosenberg, the Lab's director of Conservation Science. "But when you put these encounters together there is a very interesting pattern--there has been a flurry of encounters from a couple of key areas."

In another 10 instances this field season, people have reported hearing possible ivory-bill sounds--double-knocks and kent calls. In two cases, the sounds were recorded on videotape. Analysis shows the double knocks are well within the expected range of the ivory-bill's drumming cadence and frequency.

Meanwhile, the search is continuing in full force. "Our hopes are high because of what we know about the nesting ecology of Ivory-billed Woodpeckers," said Ron Rohrbaugh, director of the Ivory-billed Woodpecker Research Project. "Now is when we would expect to find them."

--Pat Leonard