Ivory-Bill "Knock-Knock" Puts Joke on Skeptics

James Owen
for National Geographic News

August 4, 2005

Now even the skeptics agree that the ivory-billed woodpecker lives.
The proof? Audio recordings of the birds' telltale knocking that
suggest there are at least two ivory-bills living in an area of
Arkansas swamp forest.

The new evidence comes some three months after researchers announced to the world that an ivory-billed woodpecker, a bird thought extinct for 50 years, had been seen in the Big Woods region of Arkansas.

The rediscovery of (Campephilus principalis) was hailed as the birding-world equivalent of finding Elvis alive.

The original identification rested on analysis of brief and blurry video footage of an ivory-bill recorded last year.

Last month three ornithologists said they planned to challenge the video evidence, arguing that the bird shown was actually a pileated woodpecker, a much smaller but otherwise similar-looking species.

This week, however, the experts made an about-face after listening to the new recordings. Richard Prum, a Yale University ornithologist who led the skeptics, said the tapes are conclusive.

"We were very skeptical of the first published reports and thought that the previous data were not sufficient to support this startling conclusion," he said. "But the thrilling new sound recordings provide clear and convincing evidence that the ivory-billed woodpecker is not extinct."

Double Raps

Prum says the unpublished recordings include a series of distinctive "kent" call notes and an exchange of telltale "double raps" between two individual ivory-bills.

Fellow former skeptic Mark Robbins, of the University of Kansas, says the rapping sounds are similar to those made by ivory-bill relatives native to Central and South America.

The sounds were recorded in January in Arkansas's White River National Wildlife Refuge and Cache River Refuge, according to Scott Simon, director of the Nature Conservancy in the state.

Both refuges lie in the Big Woods region, a 550,000-acre (220,000-hectare) corridor of forested swamps and floodplain in the Mississippi Delta.

Full details of the new audio evidence will be presented later this month at the American Ornithologists' Union meeting in Santa Barbara, California.

Simon says researchers were able to identify the ivory-bill's raps, which are used for communication, by calculating the time between each knock. He says the rapping speed is very fast (70-80 milliseconds) for many species of Campephilus.

"Because they have such a large bill, they can communicate very far by rapping," he added.

Simon belongs to the ivory-bill research team that announced the bird's rediscovery in April.

Holy Grail

At the time, team leader John W. Fitzpatrick, director of the Cornell Lab of Ornithology, described the red-crested, black-and-white woodpecker as the holy grail for U.S. birders. The last previous confirmed sighting occurred in 1944 in Louisiana.

Despite the recent challenge, Fitzpatrick remained confident that the bird's survival in the Big Woods region would be confirmed.

"We remain fully convinced that at least one bird was present in 2004 and early 2005," he told National Geographic News last week.

Karen Foerstel, spokesperson for The Nature Conservancy, said, "We are glad that the scientific consensus of the bird's existence is continuing to grow. Now, more than ever, it is critical to continue our work to conserve the forest habitats of Arkansas for the ivory-bill and the hundreds of other species that rely on the woods for survival."

The team plans to continue their search this fall when reduced leaf cover should increase the chances of catching further glimpses of the elusive bird.

Meanwhile, the Cornell Lab of Ornithology has produced a new, online guide to assist amateur birders keen to search for the woodpecker themselves. The Web site includes tips on how to tell an ivory-bill from a pileated woodpecker and a place to report sightings.

The ivory-bill's historic range covers much of the southeastern U.S. However, the bird only inhabits mature lowland forests, where it strips bark off dying trees with its powerful beak to reach insect grubs.

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