Map of the Chickadee Hybrid Zone (image) Cornell University Caption The two chickadee species overlap in a narrow band across the eastern United States. This band has moved northward by seven miles in the last decade. Image courtesy Cornell Lab of Ornithology. Credit Cornell University Lab of Ornithology Usage Restrictions Include credit when publishing. Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.