Christmas bird count volunteer braving the cold Photo: Gabriel Willow
This holiday season marks the 111th year of the Christmas Bird Count (CBC). The 111th CBC runs from December 14, 2010 through January 5, 2011. It is the longest running citizen science survey in the world. Thousands of volunteers, "binocular brigades," have already braved winter's chill, rain and snow to record changes in populations of bird species. This tradition was started by ornithologist Frank Chapman on December 25, 1900. Chapman, an officer in the National Audubon Society, suggested starting a Christmas trend of counting birds instead of killing them. Previously, people would spend their Christmas day competitively hunting birds and small mammals. Chapman's group counted and recorded the birds they saw, thus seeding a conservation effort and database that has grown over the last century.
For that 1st count, there were 27 bird observers who participated in 25 places in North America. Since then, the CBC has been held every year. In recent years, there have been more than 60,000 observers involved in over 2,100 places and 17 countries counting more than 2,000 species and 56 million birds. The Audubon Society, who sponsors the CBC, now partners with organizations in other counties such as Bird Studies Canada, the Red Nacional de Observadores de Aves (RNOA, National Network of Bird Observers) and the Instituto Alexander von Humboldt of Colombia.
The CBCs are conducted by volunteers attempting to record every bird they encounter within a designated 15-mile diameter "count circle" on a given calendar day. The volunteers split into small groups and follow assigned routes, which are fairly consistent each year, counting each bird they see. In some count circles, people also watch feeders. Not all the area in the count circles is covered, and not every bird along the routes is identified. The rules prohibit counting birds when retracing one's route, except for species the group hasn't seen before, in an attempt to avoid double counting. Flocks are difficult to count precisely, so an expert will estimate the number for that species during the morning or evening and usually no individuals are counted at other times. Accuracy is also assured by having new volunteers join an established group that includes at least one experienced birdwatcher.
The volunteers come for the fun, but the surveys are actually valuable for science and used in peer reviewed studies. The surveys (available back to 1900) are added to a growing database that provides information to researchers who study winter bird populations across North America. Local CBC data are then sent to the National Audubon Society. In aggregate, they're used to monitor the fluctuating populations of species, by extension the health of the birds and their environment, and what needs to be done to protect them. The data informs the U. S. State of the Birds Report, issued by the Department of the Interior each year. CBC analyses also reveal how some species have been experiencing declines. For example, the Common Grackle has declined by 60% over the past 40 years. In parts of California, the yellow-billed cuckoo, clapper rail, willow flycatcher and burrowing owl have been in decline, largely because of loss of wetlands and salt marsh habitats. But on occasion, the CBCs also show recoveries.
The New York City CBC was held last weekend on December 18th and 19th. On December 18th, birders met in South Brooklyn and Queens and counted 53 species in Canarsie and Bergen. On December 19th, they met in Central Park and counted 62 species. A highlight in Brooklyn was a red-shouldered hawk. Highlights in Central Park were a Carolina Wren and a young Red-tailed Hawk.
Out West, 200 volunteer birders gathered for the Oakland CBC. The Oakland CBC typically records more than 170 bird species. This CBC culminates with a celebratory dinner where final counts are tallied and rare-bird sighting stories are exchanged. A highlight in Oakland was a Yellow-billed Loon. Other uncommon species reported included: Snow and Ross Geese, a Bald Eagle, a Black-throated Gray Warbler, Baltimore Oriole, and an Evening Grosbeak. Yellow-billed Loon, Violet-green Swallow, and Baltimore Oriole were new to the Oakland CBC (none of the rarities has yet been reviewed by the count's Rare Bird Committee). The final Oakland numbers are still being tallied.
Other CBCs are also still taking place over the next week so check your local Audubon's event calendar if you would like to participate. For instance, if you missed the Oakland CBC- the San Francisco CBC is scheduled for December 28th and includes the north tower of the Golden Gate Bridge to the wetlands north of SFO. The San Francisco count typically records 160 species. The greatest number of bird species reported in U.S. location during a single count is 250, observed on December 19, 2005 in the Matagorda County-Mad Island Marsh CBC in Texas.
Whatever your motivation for participating, for the love of birding or the competition of counting the most species, the CBC demonstrates both the power of citizen science and that volunteers really do count!
Here is to 111 years and counting!
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This post is dedicated to Professor W.John Smith who taught me how to mistnet