Last Wednesday, at the annual meeting of the American Ornithologists' Union, 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.

Mr Charif, a research biologist at the lab who played the sounds at the meeting, 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." he said.

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.

Charif did not claim they were conclusive proof of the bird's existence. There is further analysis to do and more acoustical evidence to gather.

(Xinhua News Agency August 29, 2005)