A - C
CBC
The CBC "is the oldest and largest wildlife survey in the world" (Butcher 1990). The National Audubon Society sponsors the survey and publishes results. It is designed as a series of circular count areas, and birders count birds within these "circles" each year on a prespecified day around 25 December. With lots of circles (over 1,500) and a long history (the CBC was started in 1900), it is hard to dispute Greg Butcher's "oldest and largest" label for the survey (Butcher 1990). For more information, link to "http://www.mbr-pwrc.usgs.gov/bbs/int1cbc.html"