The Black-capped and Carolina chickadee’s range only barely intersects, so identification is typically as easy as finding out which side of the line you are on. Unfortunately, for those within a few tens of miles of the line, a confident ID may not be possible. The following paper contains a map showing the location of the hybrid zone: https://doi.org/10.1002/ece3.5497 Do you want to learn more bird songs, frog calls, and insect noises? Join Voice of the Wild every Friday to explore a new wild voice. We’re available on most podcast platforms, including Apple Podcasts, Spotify, and YouTube. Subscription links Here Subscribe to the Newsletter Listen online on our Homepage  The following Cornell Lab | Macaulay Library recordings were used in this episode: Black-capped chickadee song by Matthew D. Medler (ML508153) Black-capped chickadee call by Geoffrey A. Keller (ML508154) Carolina chickadee song and call by Wil Hershberger (ML508127)  Sources and more: https://www.allaboutbirds.org/guide/Black-capped_Chickadee https://www.audubon.org/field-guide/bird/black-capped-chickadee https://www.allaboutbirds.org/guide/Carolina_Chickadee https://www.audubon.org/field-guide/bird/carolina-chickadee Dobson C, Kassenbaum D, Oehmke D, et al. 2023. Field guide to hotspots and birds in Illinois. Champaign-Urbana: Scissortail LLC. Kroodsma DE, Albano DJ, Houlihan PW, et al. 1995. Song Development by Black-Capped Chickadees (Parus Atricapillus) and Carolina Chickadees (P. Carolinensis). The Auk. 112(1):29–43. https://doi.org/10.2307/4088764. National Audubon Society videoguide to the birds of North America. 2004. Fullscreen. Carrboro, NC: Godfrey-Stadin Productions. Peterson RT, Peterson VM. 1980. A field guide to the birds : a completely new guide to all the birds of eastern and central North America. Fourth edition, completely revised and enlarged. Boston: Houghton Mifflin Company (The Peterson field guide series ; 1). Robbins MB, Braun MJ, Tobey EA. 1986. Morphological and Vocal Variation Across a Contact Zone between the Chickadees Parus Atricapillus and P. Carolinensis. The Auk. 103(4):655–666. https://doi.org/10.1093/auk/103.4.655. Sibley D. 2016. Sibley birds East : field guide to birds of eastern North America. Second edition. New York: Alfred A. Knopf (Field guide to birds of eastern North America). 

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