Christmas Bird Count Circles in the Western Hemisphere.

The data collected by observers over the past century allow researchers, conservation biologists, and other interested individuals to study the long-term health and status of bird populations across North America. When combined with other surveys such as the Breeding Bird Survey, it provides a picture of how the continent's bird populations have changed in time and space over the past hundred years.

The long term perspective made possible by the Christmas Bird Count is vital for conservationists. It informs strategies to protect birds and their habitat - and helps identify environmental issues with implications for people as well. For example, local trends in bird populations can indicate habitat fragmentation or signal an immediate environmental threat, such as groundwater contamination or poisoning from improper use of pesticides.

In the 1980's CBC data documented the decline of wintering populations of the American Black Duck, after which conservation measures were put into effect to reduce hunting pressure on this species. More recently, in 2007, the data were instrumental in the development of two Audubon State of the Birds Reports - Common Birds in Decline, which revealed that some of America's most beloved and familiar birds have taken a nosedive over the past forty years, and WatchList 2007, which identified 178 rarer species in the continental U.S. and 39 in Hawaii that are imperiled. These two reports helped scientists and policy-makers to both identify threats to birds and habitat, and promote broad awareness of the need to address them.