Double Knocks from the Big Woods of Arkansas

In more than 17,000 hours of recordings, thousands of double-knock sounds were detected. After eliminating noises made by raindrops, gunshots, and other sources, researchers at the Cornell Lab of Ornithology found about 100 double knocks that sound tantalizingly similar to the double knocks of other Campephilus woodpeckers. Listen to the three examples below.

Double knock, December 25, 2004

Three double knocks, January 24, 2005

Three double knocks, February 5, 2005




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