The Christmas Bird Count (CBC) is a census of birds in the Western Hemisphere, performed annually in the early Northern-hemisphere winter by volunteer birdwatchers and administered by the National Audubon Society. The purpose is to provide population data for use in science, especially conservation biology, though many people participate for recreation. The CBC is the longest-running citizen science survey in the world.
History
right|thumb|[[Frank Chapman (ornithologist)|Frank Chapman, who first proposed the Christmas Bird Count.]]
In the 19th century, many North Americans participated in the tradition of Christmas "side hunts", in which they competed at how many birds they could kill. In December 1900, the U.S. ornithologist Frank Chapman, founder of Bird-Lore (which became Audubon magazine), proposed counting birds on Christmas instead of killing them.
On Christmas Day of that year, 27 observers took part in the first count in 25 places in the United States and Canada. The participants counted 18,500 birds in 90 species. The greatest number of bird species ever reported by any U.S. location in a single count is 250, observed on December 19, 2005, in the Matagorda County-Mad Island Marsh count circle around Matagorda and Palacios, Texas.
Methods
Each individual count is performed in a "count circle" with a diameter of . At least ten volunteers, including a compiler to manage things, count in each circle. They break up into small parties and follow assigned routes, which change little from year to year, counting every bird they see. In most count circles, some people also watch feeders instead of following routes.
Counts can be held on any day from December 14 to January 5 inclusive.
The results, providing data on winter ranges of birds, are complementary to those of the Breeding Bird Surveys.
See also
- Australian Bird Count
- BioBlitz – "24-hour inventory"
- Breeding Bird Survey
- Great Backyard Bird Count
- Tucson Bird Count
- Citizen science