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On Christmas Day in 1900, small groups of birdwatchers across the U.S. spent a day listing all the birds they could see. They may not have known it then, but this marked the start of an annual tradition that – more than 120 years later – helps scientists understand how climate change affects birdlife in the 21st century. Today, the  (CBC) is a prime example of how everyday observations from first-time volunteers and experts alike can make a big difference in understanding our world.

While the first count started on Christmas, the CBC has since become an annual weeks-long community science effort open to all. Last year, we had nearly 82,000 participants in 2,600 groups focused on geographic areas called “count circles” across the Western Hemisphere – including nearly 30 different countries outside the United States and Canada. This winter tradition continues to grow as bird-loving volunteers of all skill levels contribute to more than twelve decades of data.

Long-term trends in that data show dramatic changes in bird communities, even within the past few decades. Thirty-five years ago, about 1,500 count circles recorded 100 million individual birds. In comparison, for the 122nd count last year, more than 2,600 groups counted only 42 million birds. That means that participants are seeing less than half as many birds three decades later, even though the coverage and effort have substantially increased.

Birds are telling us that we are in trouble. CBC counts were among the data used in a groundbreaking study that found that we have lost three billion birds in North America since 1970. We also know that climate change is the biggest threat to birds and people alike – and it is already having an effect.

In a new climate study published this year, ̽����ѡ researchers looked at 90 years of CBC data. They found that winter ranges for many birds of the eastern United States have changed in response to climate-related changes in temperature and precipitation. This is consistent with our 2021 climate study that used CBC data to determine that many duck species that winter in the Southeastern U.S. have shifted northward due to temperature changes. Birds with specific habitat needs will be even more restricted by habitat availability and land-use change in a climate-disrupted future.

While the findings are alarming, they are helping scientists and conservation experts figure out how to protect wildlife. Understanding how wildlife is affected can help us make their habitats more adaptable and resilient to future changes. For example, ̽����ѡ’s National Wildlife Refuge study has prompted the U.S. Fish and Wildlife Service and other federal agencies to manage natural resources differently to effectively help protect the places birds need now and in the future.

The next time you go for a nature walk or explore your neighborhood, record the wildlife you see. Your observations can help improve how we protect our environment. The thousands of birders joining a Christmas Bird Count between December 14 and January 5 aren't just enjoying a day outdoors. They are also serving as community scientists, helping to protect the nature we love for generations to come. We encourage bird lovers of all skill levels and abilities to learn more about how to join by visiting www.christmasbirdcount.org.