The two chickadee species meet and hybridize in a narrow zone that has shifted northward 7 miles in the last decade.
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Ithaca, N.Y.-The zone of overlap between two popular, closely related backyard birds is moving northward at a rate that matches warming winter temperatures, according to a study by researchers from the Cornell Lab of Ornithology, Villanova University, and Cornell University. The research was published online in Current Biologyon Thursday, March 6, 2014.
In a narrow strip that runs across the eastern U.S., Carolina Chickadees from the south meet and interbreed with Black-capped Chickadees from the north. The new study finds that this hybrid zone has moved northward at a rate of 0.7 mile per year over the last decade. That’s fast enough that the researchers had to add an extra study site partway through their project in order to keep up. Read more