Christmas Bird Count
Encyclopedia
The Christmas Bird Count (CBC) is a census of bird
s in the Western Hemisphere, performed annually in the early Northern-hemisphere winter by volunteer birders. 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 America
ns 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. At the end of that century the U.S. ornithologist Frank Chapman
, an officer in the recently formed National Audubon Society
, proposed counting birds on Christmas instead of killing them.
In 1900, 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). The 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
.
Counts can be held on any day from December 14 to January 5 inclusive.
The results are by no means as accurate as a human census. Not all the area even in the count circles is covered, and not every bird along the routes is seen or identified. Big flocks can't be counted precisely. Also, telling whether a bird has been counted twice can be difficult. The rules address this problem by prohibiting counting birds when retracing one's route, except for species that the party hasn't seen before. Also, when a large roost of some species occurs in a count circle, an expert estimates the number for that species during the morning or evening and usually no individuals are counted at other times. Observers can attempt to keep track of flocks of mobile birds such as crows, and can use their judgement, even sometimes recognizing an individual bird or at least that two birds of the same species are different individuals.
The results, providing data on winter ranges of birds, are complementary to those of the Breeding Bird Survey
s.
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s in the Western Hemisphere, performed annually in the early Northern-hemisphere winter by volunteer birders. The purpose is to provide population data for use in science, especially conservation biology
Conservation biology
Conservation biology is the scientific study of the nature and status of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction...
, though many people participate for recreation.
History
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
ns participated in the tradition of Christmas
Christmas
Christmas or Christmas Day is an annual holiday generally celebrated on December 25 by billions of people around the world. It is a Christian feast that commemorates the birth of Jesus Christ, liturgically closing the Advent season and initiating the season of Christmastide, which lasts twelve days...
"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. At the end of that century the U.S. ornithologist Frank Chapman
Frank Chapman
Frank Michler Chapman was a U.S. ornithologist and pioneering writer of field guides.Chapman was born in West Englewood, New Jersey and attended Englewood Academy. He joined the staff of the American Museum of Natural History in 1888 as assistant to Joel Asaph Allen...
, an officer in the recently formed National Audubon Society
National Audubon Society
The National Audubon Society is an American non-profit environmental organization dedicated to conservation. Incorporated in 1905, Audubon is one of the oldest of such organizations in the world and uses science, education and grassroots advocacy to advance its conservation mission...
, proposed counting birds on Christmas instead of killing them.
In 1900, 27 observers took part in the first count in 25 places in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
and Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, 15 of them in the northeastern U.S. from Massachusetts
Massachusetts
The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...
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). The Audubon Society now partners with Bird Studies Canada
Bird Studies Canada
Bird Studies Canada is Canada's national bird conservation organization.-Summary:The organization began as the Long Point Bird Observatory in 1960, changing its name in 1998 to reflect the growing national scope of its research programs...
, the Gulf Coast Bird Observatory of Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
(responsible for CBCs in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
), and the Red Nacional de Observadores de Aves (RNOA, National Network of Bird Observers) and the Instituto Alexander von Humboldt of Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
.
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
Matagorda, Texas
Matagorda is an unincorporated community in Matagorda County, Texas, United States. It had a population of approximately 710 in 2000. Matagorda is at the end of State Highway 60 and beginning of Farm to Market Road 2031, which runs over the Intracoastal Waterway and south to the Gulf of Mexico...
and Palacios, Texas
Palacios, Texas
-Demographics:As of the census of 2000, there were 5,153 people, 1,661 households, and 1,244 families residing in the city. The population density was 1,021.4 people per square mile . There were 1,976 housing units at an average density of 391.7 per square mile...
.
Methods
Each individual count is performed in a "count circle" with a diameter of 15 miles or 24 kilometres. 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 are by no means as accurate as a human census. Not all the area even in the count circles is covered, and not every bird along the routes is seen or identified. Big flocks can't be counted precisely. Also, telling whether a bird has been counted twice can be difficult. The rules address this problem by prohibiting counting birds when retracing one's route, except for species that the party hasn't seen before. Also, when a large roost of some species occurs in a count circle, an expert estimates the number for that species during the morning or evening and usually no individuals are counted at other times. Observers can attempt to keep track of flocks of mobile birds such as crows, and can use their judgement, even sometimes recognizing an individual bird or at least that two birds of the same species are different individuals.
The results, providing data on winter ranges of birds, are complementary to those of the Breeding Bird Survey
Breeding Bird Survey
A breeding bird survey monitors the status and trends of bird populations. Data from the survey are an important source for the range maps found in field guides. The North American Breeding Bird Survey is a joint project of the United States Geological Survey and the Canadian Wildlife Service...
s.
Participation
Participation is open to all. Observers pay a $5 fee (except feeder watchers, U.S. and Canadian participants under 19 years old, members of Bird Studies Canada, and Latin Americans in their home countries). The fee supports compilation and publication of the data. U.S. participants who pay or who are 18 or under receive a copy of the issue of American Birds that summarizes the results and includes articles on trends and regions.See also
- Australian Bird CountAustralian Bird CountThe Australian Bird Count was a project of the Royal Australasian Ornithologists Union . Following the first and successful Atlas of Australian Birds project, which led to the publication of a book on the distribution of Australian birds in 1984, it was suggested by Ken Rogers that the RAOU...
(ABC) - BioBlitzBioBlitzA BioBlitz, also written without capitals bioblitz, is an intense period of biological surveying in an attempt to record all the living species within a designated area. Groups of scientists, naturalists and volunteers conduct an intensive field study over a short, usually 24 hour, time...
("24-hour inventory") - Breeding Bird SurveyBreeding Bird SurveyA breeding bird survey monitors the status and trends of bird populations. Data from the survey are an important source for the range maps found in field guides. The North American Breeding Bird Survey is a joint project of the United States Geological Survey and the Canadian Wildlife Service...
- Tucson Bird CountTucson Bird CountThe Tucson Bird Count is a community-based program that monitors bird populations in and around the Tucson, Arizona, USA metropolitan area...
(TBC) (in Arizona in the US)