Christmas Bird Counts

Project Description
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