Christmas bird count

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.

Up through 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, regardless of whether they had any use for the carcasses and of whether the birds were beneficial, beautiful, or rare. 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.

That year, 27 observers took part in the first count in 25 places in the United States and Canada, 15 of them in the northeastern U.S. from Massachusetts to Philadelphia. Since then the counts have been held every winter, usually with increasing numbers of observers. For instance, the 101st count, in the winter of 2000–2001, involved 52,471 people in 1,823 places in 17 countries (but mostly in the U.S. and Canada). During the 113th count (winter 2012–2013), 71,531 people participated in 2,369 locations. The National Audubon Society now partners with Bird Studies Canada, the Gulf Coast Bird Observatory of Texas (responsible for CBCs in Mexico), and the Red Nacional de Observadores de Aves (RNOA, National Network of Bird Observers) and the Instituto Alexander von Humboldt of Colombia.

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. The greatest number of bird species ever reported by a CBC circle in the world is 529, observed on December 21, 2013 in the Cosanga-Narupa count (previously known as the Yanayacu count) on the eastern slope of the Andes in Ecuador.

...
Wikipedia