Carolina or Black-Capped Chickadee? Sometimes It’s a Hard Call

By Zach Ladin

A black-capped chickadee in Monocacy National Battlefield.

NPS

Chick-a-dee-dee-dee…………….chick-a-dee-dee-dee! Hear that? It’s a chickadee. Obviously. But is it a black-capped or a Carolina? If you’re a birder, you might be able to tell, but around here it can be tricky. That’s because the National Capital Region (NCR) intersects with a “zone of overlap” where Carolinas and black-cappeds can hybridize, or might just have learned each other’s vocalizations.

Chickadees are songbirds in the family Paridae. They flit through forests in small gangs like tiny, feathered, perpetual motion machines. They may be small, but they have big personalities. Chickadees are year-round residents here, and can often be seen foraging at backyard bird feeders. Of the five species of chickadees found in North America, the two most abundant species of chickadees in the eastern US are the black-capped (Poecile atricapillus) and Carolina (Poecile carolinensis).

Carolina Chickadee (Poecile carolinensis) calls are a higher and faster chick-a-dee-dee-dee. The song is four notes, fee-bee-fee-bay.

NPS/ Neal Lewis

Most of the NCR lies within Carolina chickadee territory, but Catoctin Mountain Park and the upper reaches of Chesapeake & Ohio Canal National Historic Park are in or very near where the area where the two species ranges overlap. Hybridization in the overlap zone reduces reproductive success rates, and produces birds with intermediate plumage and modified songs that combine primary song characteristics of both species. It can also lead to one species singing the unmodified songs of both species. Discerning a Carolina from a black-capped within this zone of overlap can be tricky, even for experienced birders.

Black-capped Chickadee (Poecile atricapillus) calls are a lower and slower chick-a-dee-dee-dee, while the song is a clear fee-bee.

NPS

The NCR Network’s Inventory and Monitoring (NCRN I&M) program has monitored forest-breeding land birds since 2007, providing not only valuable information on bird populations but also data on the health of forest ecosystems. Monitoring has shown that Carolina chickadees are some of the most abundant and densely occurring species within the NCR. Chickadees typically have a single brood per breeding season, which is one life history characteristic used to evaluate forest quality according to a measure called the Bird Community Index.  This index provides a way to measure forest quality based on the community of bird species detected within the NCR. Continued monitoring will enable us to evaluate changes in the health of forests and better understand the factors and implications of bird population trends over time.

References

• Brewer, Richard. Ecological and Reproductive Relationships of Black-Capped and Carolina Chickadees. The Auk, vol. 80, no. 1, 1963, pp. 9–47. JSTOR, https://doi.org/10.2307/4082581.
• Ladin, Z. S., and W. G. Shriver. 2011. Avian Monitoring in the National Capital Region Network: 2007 – 2011. Natural Resource Technical Report NPS/ /NCRN/NRDS—2011/***. National Park Service, Fort Collins, Colorado, USA.
• Reudink, M. W., S. G. Mech, S. P. Mullen, R. L. Curry, and J. Klicka. 2007. Structure and dynamics of the hybrid zone between black-capped chickadee (Poecile atricapillus) and Carolina chickadee (P. carolinensis) in southeastern Pennsylvania. The Auk 124:463-478.
• Connor, Jack. 2008. Some Chickadees Are Bilingual—But Why? Cornell Lab of Ornithology.

More on Birds

The NCR Inventory & Monitoring Network monitors birds in forests and grasslands. To learn more about this monitoring, visit the NCRN I&M bird monitoring page to view the latest reports and resource briefs.

This material was originally published in a newsletter in 2012, and was republished in an online format in 2024.