Mark Robbins says he now has proof – it really was an ivory-billed woodpecker that scientists saw this spring in Arkansas.

Robbins, collections manager at the Kansas University Natural History Museum, and several colleagues were set to publish a paper challenging whether the bird – thought to be extinct for more than 60 years – really had been sighted.

But recordings provided Sunday convinced Robbins and Richard Prum, a Yale University ornithologist who was lead author of the paper, and others that the ivory-billed woodpecker is alive and well, according to a Yale press release.

“The thrilling new sound recordings provide clear and convincing evidence that the ivory-billed woodpecker is not extinct,” Prum said.

Robbins, who could not be reached for comment Monday evening, and his colleagues had submitted a paper to the Public Library and Science journal. The paper questioned whether fuzzy video collected in April by researchers led by Cornell University was enough to prove the ivory-billed woodpecker wasn’t extinct.

Instead, scientists believed the group saw a common pileated woodpecker.

But the new recordings, Robbins said in the press release, provided undeniable evidence. The recordings, which the group challenging the sighting first heard Sunday, were a series of “double raps” made with the woodpecker’s bill. The Cornell group plans to release the recordings in August at the meeting of the American Ornithologists’ Union.

Those raps, along with answering raps from a second bird, are unique among the ivory-billed species.

“These recordings of the double raps sound very natural,” Robbins said, “and they were totally consistent with the behavior of the Central and South American relatives of the ivory-billed woodpecker.”