Eastern Chickadee Populations Moving North Fast In Response To Warming World
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A group of East Coast university researchers probably felt that way as they studied the breeding areas of Carolina and black-capped chickadees. Along a narrow zone in the eastern U.S., the two species interbreed, and that overlap zone is moving northward at 0.7 miles per year — a full-on sprint by geological time standards.
“A lot of the time climate change doesn’t really seem tangible,” said lead author Scott Taylor, a postdoctoral researcher at the Cornell Lab of Ornithology. “But here are these common little backyard birds we all grew up with, and we’re seeing them moving northward on relatively short time scales.”
The birds moved so fast the scientists had to add an extra study site partway through their project in order to keep up. In Pennsylvania, where the study was conducted, the hybrid zone is just 21 miles across on average. Hybrid chickadees have lower breeding success and survival than either of the pure species. This keeps the contact zone small and well defined, making it a convenient reference point for scientists aiming to track environmental changes.
“Hybridization is kind of a brick wall between these two species,” said Robert Curry, a professor of biology at Villanova University, who led the field component of the study. “Carolina Chickadees can’t blithely disperse north without running into black-caps and creating hybrids. That makes it possible to keep an eye on the hybrid zone and see exactly how the ranges are shifting.”
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http://summitcountyvoice.com/2014/03/08/study-eastern-chickadee-populations-moving-fast-in-response-to-global-warming/
