Wednesday, April 16, 2014
IVORY BILLED WOODPECKER
Over the years, sightings of ivory-billed woodpeckers -- some more credible than others -- were reported regularly from Louisiana, Florida and more recently, Arkansas. None of these observers managed to get a photograph or movie of the birds.
The chance of confusing a pileated woodpecker for an ivory-billed woodpecker is high, particularly if the sighting is brief. Nevertheless, a spate of sightings from the Cache River in eastern Arkansas were convincing enough for the Cornell Laboratory of Ornithology to mount a large expedition there in fall 2004.
Their best evidence for an ivory-billed woodpecker was a brief videotape, taken by David Luneau, an electronics professor at the University of Arkansas-Little Rock. Luneau kept his videocamera recording on the gunwale of his canoe and by luck captured a brief flight of a large woodpecker.
The Cornell team also had a series of automated recording devices throughout the Cache River swamp. Recordings were captured of the ''kent'' calls that ivory-bills give as well as the double-tap knocks the birds use to communicate.
The elation of a number of ornithologists and birders flagged upon examination of the data. I think the words of Carl Sagan, the eminent astronomer and stalwart of the skeptic movement in the U.S., are appropriate in this case: ''Extraordinary claims require extraordinary evidence.''
A close examination of the Luneau video convinced some ornithologists that the bird was actually a pileated woodpecker rather than an ivory-bill. The acoustic evidence was questioned because blue jays give a ''kent'' call, even in areas where ivory-billed woodpeckers never occurred. Pileated woodpeckers will give double tap signals.
''Ghost Bird'' explores the impact of the claimed ivory-billed sightings on the town of Brinkley, Ark. One citizen said only one person in Brinkley even knew what an ivory-billed woodpecker was before the 2005 announcement. At least six businesses have sprung up in Brinkley, all capitalizing on the ivory-billed woodpecker. Where else can you get a woodpecker haircut for $25?
Crocker reviews the data used to support the claim of living ivory-billed woodpeckers, including multiple showings of the Luneau video. We see lots of footage of the Cache River swamps.
Two skeptical scientists are extensively interviewed. Dr. Jerry Jackson of the Florida Gulf Coast University is the eminent living authority on ivory-billed woodpeckers and has conducted searches for these birds. Dr. Rick Prum of Yale University provides his perspective as well.
David Sibley, author of the best-selling field guide on North American birds, went to Arkansas after the initial announcement. He noted that earlier workers found that ivory-billed woodpeckers preferred to forage on Nuttall oaks. In eight days of dawn to dusk field work, Sibley found no evidence of woodpecker excavations or bark stripping on these oaks.
Crocker does a nice job of documenting the history of the decline of the ivory-billed woodpecker. Jim Tanner studied ivory-billed woodpeckers in the Singer Tract of Louisiana between 1937 and 1941 for his doctoral research at Cornell University. He and his wife, Nancy, saw and photographed ivory-bills there for the last time in 1941. Nancy Tanner is still living and, in the film, offers a fascinating glimpse into history.
The Cornell Laboratory of Ornithology continues to maintain that its evidence is sufficient to demonstrate that the ivory-billed woodpecker still survives. Unfortunately, the lab would not allow any of its employees to be interviewed for this documentary.
The initial excitement over the rediscovery of the ivory-billed woodpecker led to changes in funding for conservation. The U.S. Fish and Wildlife Service provided an initial $10 million to help conserve the ivory-bill. These funds had to be provided by taking money from other projects designated for the protection of other endangered species. An additional $27 million was provided in 2007. A number of conservation biologists have questioned this reallocation of limited funds.
I highly recommend this film, which screens today and Monday. Visit the Maine International Film Festival Web site, www.miff.org for showtimes.
Herb Wilson teaches ornithology and other biology courses at Colby College. He welcomes reader comments and questions at: