This video from the USA says about itself:
Research update: New chickadee study shows climate change affecting distribution
6 March 2014
The zone of overlap between two popular, closely related backyard birds—the Carolina Chickadee and the Black-capped Chickadee—is moving northward at a rate that matches warming winter temperatures, according to a March 2014 study by researchers from the Cornell Lab of Ornithology, Villanova University, and Cornell University. Read the full article here.
The Cornell Lab of Ornithology writes:
Way to Go, Chickadees!
NestWatchers just broke the record for number of Carolina Chickadee nests submitted to NestWatch! So far this year, 462 nests have been submitted. The state submitting the most nest attempts, fittingly, is South Carolina.
While still quite common, the Carolina Chickadee has undergone significant population declines in recent years. If you live in the appropriate range and habitat for Carolina Chickadees, you can put up a nest box to encourage nesting. This is one of our focal species, and we are grateful for more data on this species’ nesting success.
Carolina Chickadees are also moving north, and they are nesting in more northern areas now than they were a decade ago.
Black-capped chickadee: here.