The annual event, now approaching its 111th season, involved counting teams across Canada, all 50 United States, the Northern Mariana Islands, Guam, Mexico, Belize, eight countries in Central and South America, Trinidad, the Bahamas, Bermuda, the Dominican Republic, Puerto Rico and the Virgin Islands.
The Audubon Society’s Christmas Bird Count
The National Audubon Society was founded in 1905, but the Christmas Bird Count (CBC) was initiated five years earlier by Frank Chapman, an ornithologist at the American Museum of Natural History. Chapman proposed the bird count as an alternative to an annual event called the “side hunt”, where participants chose sides and competed to see which side could shoot and kill the most number of birds. Fortunately, the CBC outlasted the “side hunt”, and has continued to grow for 110 years.
The CBC is a volunteer, citizen science event open to everyone. Designated counting sites, 15 miles in diameter, are predetermined by the Society, and a field party under the coordination of an experienced leader (compilier) conducts the count in each CBC circle. Each group spends one day between December 14 and January 5 recording every bird seen or heard that day, and the group leader summarizes all counts by species on special forms which are returned to the Society for final tabulation. Participants over the age of 18 pay a five dollar fee to help offset census costs.
Data collected by these counting groups have proven invaluable, providing statistics for biologists, conservationists and other researchers. CBC data have been employed in many useful ways, including documentation of declining populations, which has led to increased conservation measures.
Counting Birds during Adverse Winter Conditions
Counting birds in Norh America in the winter can be challenging, and since most of the counting activity takes place in the U.S. and Canada, many of the field teams encounter tough weather. This year, counting teams in the northeast had to deal with severe snowstorms, up to 20-inch, 24-hour snowfalls in eastern Ontario, 40-mile per hour winds in New York and deep snow, freezing temperatures and fog in the Washington, D.C./Virginia area.
Keeping things in perspective, however, the journal includes a fascinating article by Paul Hess, Birding in the Twilight Zone, which describes extreme conditions encountered during prior CBCs in the Arctic and Antarctic. Some of the counts described by Hess make the challenges of the 110th count pale, including windchills of 70 degrees below zero Fahrenheit, birdless days, whiteouts, bears and 24-hour twilight where the sun sets in November and doesn’t break the horizon until February.
In spite of conducting these counts at year’s end, however, participation continues to grow and records continue to be set.
Highlights of the 110th Annual Audubon Christmas Bird Count
Geoffrey S. LeBaron, the Society’s CBC Director, opens the journal’s findings with a piece that calls this count “record shattering.” Total counts, at 2,160, set a new record, exceeding the prior year’s number, which was itself a record. 1,671 of these were in the U.S., 382 in Canada and 107 from the other areas, with Colombia taking third place at 35 counts. A record was also set for the number of observers, 60,753, of which 79% were in the U.S.
The total number of birds counted was nearly 56 million, significantly less than recent years, but this is likely the result of combined factors, including severe weather, lack of Irruptive U.S. species and fewer communal roosts.
Helped no doubt by increased participation in Latin America, total bird species climbed to 2,319, an increase of 8.6% (about 200) over the prior year. This number represents about 23% of the roughly 10,000 bird species worldwide. 165 species of hummingbirds and 147 species of tanagers were tallied, or about half of the world’s total for these western hemisphere specialties. 379 species were documented in Canada, and 654 species plus 42 additional forms recorded in the U.S. One of the more remarkable U.S. recordings was a Bare-throated Tiger-Heron at Anzalduas-Bentsen, Texas, a first-ever record for the CBC, Texas and the American Birding Association areas. This bird was discovered prior to the count, on December 21, and was considerate enough to stick around for the official count date on January 5.
Amazingly, 112 counting teams tallied 150 or more species. Texas took the top North American spot (Matagorda County-Mad Island Marsh, with 231 species) and the top 17 North American counts were recorded in either Texas or California. South of the border, bird-rich Ecuador took the top two spots (418 and 414 species), followed closely by five Costa Rican counts, and a total of 13 Latin American teams recorded counts higher than the highest count recorded above the U.S./Mexican border.
Trends suggested by the counts include a continuing decline in the Northern Bobwhite and Gray Partridge, and a continued expansion, both in range and numbers, of the Eurasian Collared-Dove, a bird which colonized in Florida in the 1980s. Vermilion Flycatchers and Broad-winged Hawks appear to be overwintering in the U.S. in increasing numbers, a development that will be tracked by the CBCs of the future.
Volunteering to Join Audubon’s 2010-2011 Christmas Bird Count
Anyone can volunteer to join a CBC team. Audubon maintains a CBC web page where, beginning in November, you can search for the nearest count circles. Actual count dates are entered as compilers determine them, and it may be necessary to monitor the site if count dates for circles of interest are not posted immediately.