Analysis of more than 4,000 hours of digital data captured by 12 acoustic recording units (ARUs), developed by the Cornell lab's team of bioacoustics engineers, have shown no indication of the species' presence.
"As you can imagine, this is not what we had hoped for," says John Fitzpatrick, director of the Cornell Lab of Ornithology and a leader of the expedition. "Although we're disappointed by the results so far, it is important from a biological as well as a historical standpoint to determine once and for all the status of this magnificent bird."
From late January through mid-March, the ARUs recorded sounds, natural and otherwise, from 12 different positions throughout the forests of the Pearl River drainage, where they had been deployed by researchers following rugged hikes through bayous, brambles and mud. At one point during the exploration, two different research teams independently heard loud double raps that sounded suspiciously like the distinctive display drum of the ivory-billed woodpecker.
Sadly, analysis of the ARU data proved that the sounds were distant gunshots, with reverberations that sounded to human ears like drumming on a hollow snag. "If there is good news here, it is in knowing that the ARU technology could provide independent and conclusive evidence as to the nature of these sounds," says Fitzpatrick.
Fitzpatrick adds that he does not consider the results of this winter's work to be conclusive as to the presence or absence of ivory-billed woodpeckers in southern Louisiana, or even in the Pearl River forests. Persistent accounts bearing a reasonable level of credibility suggest that the possibility demands continued scientific inquiry. Ivory-billed woodpeckers were known to be highly mobile, sometimes moving great distances as their principal resources (large, recently dead trees) became available or aged beyond use. The bottomland hardwood forests of the lower Pearl River are extensive, and they are in better condition to support large woodpecker populations today than they have been for 100 or more years. "We do not view it as impossible that one to several pairs of ivory-bills could be using portions of the Pearl River forests that were outside the geographic scope of our search," says Fitzpatrick.
The Cornell Lab of Ornithology and Zeiss Sports Optics have had preliminary discussions about how to proceed with follow-up research. "The ivory-billed woodpecker continues to be of great interest not only to those of us involved in this recent research but to millions of people worldwide," says Anthony R. Cataldo, vice president and general manager of Zeiss Sports Optics North America. "We look forward to working with our partners at Cornell and the Louisiana Department of Wildlife & Fisheries to map out the next stages of this important research."
According to Fitzpatrick, today's renewed interest in the ivory-billed woodpecker should kindle much more than dim hopes of a dramatic rediscovery. He says that whether or not the bird still exists, the ivory-billed story demands full attention as a vivid symbol of what many view as the most comprehensive conservation failure of 20th Century America. By 1900, millions of acres of virgin pine and hardwood still existed in the southeastern United States, including in Louisiana. For a variety of reasons, those who had opportunities to do so failed to save even a single tract of this primary forest.
As a result of the expeditions, the Cornell Lab of Ornithology researchers are working with others to draft recommendations on how best to manage the habitat for continued regeneration toward old-growth conditions. "Today's generation of Louisianans will never see bottomland forests of the stature that were occupied by ivory-billed woodpeckers. Nor will their children, nor their grandchildren," says Fitzpatrick. "Conditions in the Pearl River are steadily improving but they have a long way to go before they reach the age-classes and volumes of standing dead wood that were present when the ivory-billed woodpecker was active. And, these forests are still at our mercy. We need to treat them as such."
The Cornell Lab of Ornithology is a nonprofit membership institute interpreting and conserving the Earth's biological diversity through research, education and citizen science focused on birds.