Background information

Christmas Bird Count (CBC)

The Christmas Bird Count (CBC), coordinated by the National Audubon Society and now over 100 years old, monitors the status and trends of winter bird populations through an all-day, annual census conducted by groups of volunteers throughout North America. These data reflect the distribution and numbers of winter birds over time.

CBC data were provided by the National Audubon Society and are thanks to the generous efforts of Bird Studies Canada and countless volunteers across the western hemisphere. The graph presents the annual population index and the upper and lower 95% credible intervals. CBC results presented here are the result of new hierarchical Bayesian analyses (see Soykan et al. 2016 and Meehan et al. 2018).

Data from CBC complement the North American Breeding Bird Survey (BBS) by providing results for some species that cannot be monitored in Canada on their breeding grounds. On this website, CBC results were mainly used for those species in Canada that breed in areas not well covered by the BBS, but that spend their winters in the United States and more southerly parts of Canada, where their populations can be monitored by the CBC.

Please visit the Christmas Bird Count website for more information.


Meehan, T.D., G.S. LeBaron, K. Dale, N.L. Michel, G.M. Verutes, and G.M. Langham. 2018. Abundance trends of birds wintering in the USA and Canada, from Audubon Christmas Bird Counts, 1966-2017, version 2.1. National Audubon Society, New York, New York, USA. (link)

Soykan, C.U., J. Sauer, J.G Schuetz, G.S. LeBaron, K. Dale, and G.M. Langham. 2016. Population trends for North American winter birds based on hierarchical models. Ecosphere 7(5):e01351. (link)