Multiple lines of evidence suggest that the Gray-headed Chickadee (Poecile cinctus lathami), a population endemic to Alaska and northwestern Canada, has declined and/or been extirpated from locations where they were considered historically common. In contrast, the Boreal Chickadee, a native congener, has recently colonized locations where Gray-headed Chickadees once occurred. This project focuses on whether hybridization (and subsequent transfer of genetic material from one species into another with continued breeding events overtime) between these two closely related chickadee species may be responsible for Gray-headed Chickadee declines. Specifically, our objectives are to: 1) Conduct call-playback surveys to detect chickadees (Boreal and Gray-headed) within our study area of the Kelly River region in the Noatak National Preserve, and 2) Take blood samples from Boreal Chickadees and Gray-headed Chickadees within the study area and subsequently evaluate the spatial and temporal extent of hybridization between Gray-headed Chickadee and Boreal Chickadee.