Biologists Use Bird Recording to Prove a Point

An ornithological dispute over the fate of a woodpecker thought to be extinct has been solved after experts produced recordings of its distinctive drumming sounds.

The ivory-billed woodpecker was said to be extinct for some 60 years, until US biologists claimed to have rediscovered it in April and captured it on film. Other experts said the brief, blurry video clip was inconclusive, prompting the original team to comb through 17,000 hours of audio tapes.

The recordings have now been released at the American Ornithologists' Union meeting in California by Russell Charif, a bioacoustics researcher at the Cornell Lab of Ornithology.

Richard Prum, an ornithologist at Yale University and a prominent sceptic of the bird's rediscovery, said in a statement: "The thrilling, new sound recordings provide clear and convincing evidence that the ivory-billed woodpecker is not extinct."

One recording suggests the presence of at least two birds: a signature double-rap that sounds like an ivory-billed woodpecker drumming on a tree from a distance, followed by a closer double-rap. This drumming behaviour is typical of many large woodpeckers closely related to the ivory-bill.

Other recordings include sounds that resemble the ivory-billed woodpecker's distinctively nasal calls.

The sounds were discovered by audio experts combing through hours of audio files from recording devices strapped to trees in the Arkansas woods and swamplands.

Mr Charif said the drumming could be ivory-billed woodpeckers communicating with each other by rapping on trees. "I immediately felt a thrill of excitement the first time I heard that recording. It is the best tangible evidence so far that there could be more than one ivory-bill in the area."

After eliminating thousands of noises, including gunshots, the scientists found about 100 double-knock sounds. They were clustered around specific locations at certain times of the day, showing it was not random noise.

John Fitzpatrick, the director of the Cornell lab, said: "We're excited and encouraged ... These sounds give us additional hope that a few ivory-billed woodpeckers do live in the region. But this species is still on the verge of extinction and huge mysteries remain to be solved."

Since the announcement of the bird's rediscovery, the US has announced a £5.5m project to protect its habitat.