Black-throated Green Warbler © John Heidecker 2001 Cornell Laboratory of Ornithology, Ithaca, New York.

April 9, 2001 -- As spring comes to New York City’s Central Park, so does an ornithological mystery. For the past few years, birdwatchers heard the song of the Black-throated Green Warbler (“Zee zee zee zoo zee”) several weeks before the bird's seasonal return to the park.

White-throated Sparrow © J Woodard 2001 Cornell Laboratory of Ornithology, Ithaca, New York.

Careful birdwatchers noticed that the warbler’s song was alternating with that of the more common White-throated Sparrow (“Oh Sam Peabody, Peabody”).

The mystery was solved when a veteran birder realized that there was a treetop mimic -- a single white-throated Sparrow was singing both its own song and that of the Black-throated Green Warbler.

 Listen to the Central Park mimic.

 Listen as commentator Brad Klein tells the story for All Things Considered. (Warbler recording: © 2001 Cornell Laboratory of Ornithology. Macaulay Library of Natural Sounds, Ithaca, New York. Recordist: Geoffrey A. Keller.)