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By Paul SiscoHummingbirds2 are among the most fascinating creatures in the avian world. The male Anna hummingbird1, the most common on the U.S. west coast, makes a high-pitched chirp3, or screech4, when it dives to guard its nest. But it doesn't use its voice. How it makes that sound has been a mystery until now. Two young researchers at the University of California have solved it, using a clarinet, the bird's tail feathers and a wind tunnel. VOA's Paul Sisco explains.
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