Friday, August 26, 2005

ENV: Ivory-bills sounds Part II

Birders Hear Call Linked to Good News on Ivory Bill
By JAMES GORMAN, The New York Times, August 25, 2005


SANTA BARBARA, Calif., Aug. 24 - For half a century, bird-watchers have longed for a glimpse of the ivory-billed woodpecker, a bird long given up for extinct but recently rediscovered in Arkansas. Now they may be able to hear it.

On Wednesday, at the annual meeting of the American Ornithologists' Union here, a Cornell researcher played newly recorded sounds that were believed to come from an ivory bill: a toy-trumpet call sounding like the word "kent" and a double knock on wood, made when the woodpecker hammers a tree.

It was these sounds that persuaded some skeptics this month to withdraw a critical paper and state that they were now convinced of the bird's existence.

The sounds are online at the Web site of the Cornell Lab of Ornithology: www.birds.cornell.edu.

Russ A. Charif, a research biologist at the lab who played the sounds at the meeting, did not claim that they were conclusive proof of the bird's existence. There is further analysis to do and more acoustical evidence to gather, Mr. Charif said.

But together with a blurred, heavily analyzed video, and personal sightings, the evidence for the bird's existence is now conclusive, he said.

John Fitzpatrick, the head of the Cornell lab, said after the presentation that the researchers were not retreating from their conclusion that at least one ivory bill existed in Arkansas, that it was the weight of the combined evidence that had convinced him.

The ivory-billed woodpecker, the largest American woodpecker, starkly patterned in black, white and red, had acquired near mythical status as a reminder of lost Southern forests until it was sighted twice in February 2004 in the Cache River National Wildlife Refuge.

Although other sightings had been made since the last documented one - roughly 50 years ago in Louisiana - none were confirmed and accepted by ornithologists.

In 2004 an ivory bill was sighted by Timothy Gallagher of the Cornell lab and Bobby Harrison of Oakwood College in Huntsville, Ala., as they searched the Cache River refuge in a canoe. Both men had been pursuing the bird for years and had gone to this area because of a report from Gene Sparling of Hot Springs, Ark., who thought he had seen it while kayaking earlier in the month.

The sighting by two expert birders led to a extensive but secret search and an announcement in April 2005 at a news conference and in an article in the journal Science that the bird had been found.

Serious doubts were later voiced by other ornithologists and birders, including Richard O. Prum of Yale and Mark Robbins of the University of Kansas about the evidence presented in the science paper.

But Dr. Prum and Dr. Robbins were convinced of the bird's existence after they were provided the recordings that Mr. Charif played on Wednesday.

The recordings were from the Cache River and the White River National Wildlife Refuges, and Dr. Prum and Dr. Robbins were still not convinced that the Science paper, which had not used the recordings as evidence, was conclusive. But since the larger point was moot, they withdrew a critical response to that paper.

Mr. Charif said after his talk that the "kent" sounds alone were not conclusive because scientists could not completely rule out a blue jay mimicking the sound of an ivory bill, and that there was no earlier definitive recording of the double rap.

"Our interpretation is that they provide suggesting and tantalizing evidence," he said of the recordings.

"We regard the video as being conclusive," he said, even though it was the acoustic recordings that had persuaded skeptics who found the video analysis lacking.

The recordings were made from December 2004 to May 2005 with remote recording units in the Cache River and White River refuges.

The 18,000 hours of recordings were combed, first by computer and then by humans, to pick out more than 50 double knocks and several "kent" calls.

These were more thoroughly analyzed and compared to known ivory bill recordings, and double knocks of similar species outside of the United States.


Tags: , , ,

0 Comments:

Post a Comment

<< Home