About the Christmas Bird Count

The Christmas Bird Count (CBC) is more than just a bird census—it is a conservation legacy reaching back more than 125 years, combining community, conservation, and science. As one of the world's longest-running community science projects, it provides an irreplaceable snapshot of bird populations across the Americas and the Pacific.  

What is the Christmas Bird Count?

The CBC is an annual bird census in which thousands of volunteers across the United States, Canada, Latin America, the Caribbean, and the Pacific Islands count every bird they see or hear in a designated area within a 24-hour period.

Every year local counts take place from December 14 to January 5. Each count occurs within designated circles that are 15 miles/24 kilometers wide. Volunteers join counting groups that are assigned to specific areas or bird feeders within the circle boundaries. Volunteers count every bird they see or hear while participating.  

From world-class birders to those beginning to watch birds at a backyard feeder, all are welcome to join the CBC. The CBC Community Principles* outline how CBC community members support each other and care for the birds and habitats that comprise the count.

History of the CBC: From Hunting to Counting

Before the 20th century, a Christmas holiday tradition known as the "Side Hunt" saw participants compete to see who could shoot the most birds and small mammals. On Christmas Day, 1900, ornithologist Frank M. Chapman, an early officer in the nascent Audubon Society, proposed a conservation-minded alternative: a "Christmas Bird Census." That first year, 27 dedicated birders conducted 25 counts in the United States and Canada, tallying around 90 species. Today, that small spark has grown into a hemispheric movement of more than 85,000 participants annually, proving that the power of community can change the course of conservation.

For more than a century, the results of the CBC have been meticulously documented in publications from Bird-Lore (the original CBC publication) to Audubon Field Notes, American Birds, and now digital summaries* available to everyone.

Why It Matters

Every bird counted contributes to our understanding of how bird populations are changing and what actions we need to take to protect them. CBC data don’t just sit in a database—they drive real-world conservation action and policy decisions, including the following:

• Population Trend Detection: CBC data have revealed dramatic declines in grassland birds like Eastern Meadowlark and Bobolink, which contributed to targeted habitat conservation efforts and informed the landmark 2019 study showing North America has lost 3 billion birds since 1970.
• Climate Change Documentation: CBC data have documented northward range expansions of species like Red-bellied Woodpecker and Carolina Wren, providing early evidence of climate change impacts on bird distributions and informing climate adaptation strategies.
• Species-Specific Conservation: CBC data detected population declines in American Kestrels decades before other monitoring programs, triggering research into causes and conservation interventions.
• Public Decision-Making: In addition to scientific articles, CBC data have been used by government, non-profit, and community agencies as an important basis for making decisions about bird conservation and management.

CBC by the Numbers

• 127+ years of continuous data collection
• 2,700+ active counts across the Americas and Pacific
• 85,000+ annual volunteers
• 300+ peer-reviewed scientific papers published using CBC data
• CBC results and population trend data available online*

CBC Partners

The CBC is a massive collaborative effort that transcends borders. While the National Audubon Society leads the program, its success relies on a vibrant network of partners. Visit our partnership page to learn more.  

Want to dive deeper?

For a full program overview, detailed counting protocols, and volunteer roles, check out our comprehensive Christmas Bird Count Guide*.