Over the next three weeks, about 2,000 binocular-toting volunteers described by the National Audubon Society as "citizen scientists" will fan out throughout the Bay Area for the annual Christmas Bird Count.
The nationwide surveys began in 1900 and are sponsored by the Audubon Society as a way of recording trends in bird populations.
The Bay Area now has 20 regional counts, extending from western Sonoma County to the Calero-Morgan Hill area, among more than 1,700 in the United States and 500 others in Canada and other countries.
"It's a chance to be out and enjoying birding with a purpose," said Dave Quady, who has been the co-compiler, or leader, of about 200 volunteers in an Oakland and East Bay section for the past decade.
"It's fun because it's always a challenge to see what species you will find, how many birds you will find and how thoroughly you have scanned the area," said Quady, a retired chemical engineer who lives in Berkeley.
Each section is a circle 15 miles in diameter and is surveyed on one day during the three-week holiday period. Bay Area counts kicked off with an eastern Alameda County circle today and will end with a Mount Hamilton circle in Santa Clara County on Jan. 2.
Volunteers work in small teams assigned to particular routes or areas within their circle, with experienced birders leading each team.
"People who do it year after year are treasured," Quady said.
Audubon scientists say that while no single year's survey is definitive, because of weather and other variations, the data over a decade or more can show long-term trends.
Christmas Bird Count national director Geoff LeBaron said the surveys are "a gold mine of information" used by scientists and government agencies.
One example, said California Audubon spokesman Garrison Frost, is a 2009 study in which the group used 40 years of Christmas Bird Counts to look at the effects of climate change on bird ranges in the state.
"It showed that up to one third of California's 310 native birds were in danger of significant losses to their geographic ranges," Frost said.
The study projected, for instance, that the Chestnut-backed Chickadee, which is found in the Bay Area, could lose between 16 and 49 percent of its California range in the next several decades, depending on the extent to which greenhouse gases are reduced.
"Having this information helps us make informed decisions on how climate change will affect bird ranges and gives us a much better handle on where are the best places to spend conservation money on preserving habitat," Frost said.
The counts were founded in 1900 by Frank Chapman, an ornithologist at the American Museum of Natural History in New York, member of the New York
Audubon Society and editor of a journal called Bird-Lore, which later became
Chapman proposed the counts as an alternative to a then-declining 19th century custom known as the Christmas side hunt, in which sportsmen with rifles and shotguns would choose teams or sides and compete to see which side could shoot more birds and small animals on Christmas Day.
"Now Bird-Lore proposes a new kind of side hunt, in the form of a Christmas bird-census, and we hope that all our readers who have the opportunity will aid us in making it a success by spending a portion of Christmas Day with the birds," Chapman wrote in the journal.
The first Christmas Bird Count on Dec. 25, 1900, had 27 observers conducting a total of 25 surveys, most in northeastern North America, but also one in Pacific Grove. They tallied 90 species.
LeBaron said the Bay Area plays an important role in the current national count because of the number of species it hosts and the multitude of volunteers who participate.
"It's very diverse biologically and it's blessed with a wonderful birding and scientific community," he said.
"We have a really enthusiastic birding community," Frost said.
Because the terrain includes coastline, marshes, forests and urban areas, the number of species found locally is much higher than the national average of 70 to 80 species per circle, LeBaron said.
Last year, a Point Reyes circle ranked sixth among more than 2,000
circles in the United States and Canada with a count of 206 species.
Also among the 25 highest in North America, spotters in a Crystal Springs area circle catalogued 198 species and those in the southern Marin County, western Sonoma County and Oakland-East Bay circles each found more than 180.
Circles in the Benicia, Hayward-Fremont, San Francisco and northern Peninsula, and San Jose areas reported more than 170 species.
The Bay Area also ranks high in numbers of participants, according to statistics compiled by LeBaron.
The Oakland-East Bay group was the seventh largest worldwide with 220 volunteers and Point Reyes was ninth with 199 last year.
The Oakland-East Bay circle, established in 1938, extends from Treasure Island to the San Pablo Reservoir and encompasses eight cities, regional parks, golf courses and Oakland International Airport.
Quady said most volunteers in the group's Dec. 16 survey will work on foot but some will watch for birds from two fishing boats north and south of the Bay Bridge, from a kayak in San Leandro Bay, and at bird feeders in
"It's all about geography," Quady said.
Eastern Alameda County circle co-compiler Rich Cimino said that group was founded four years ago because of concern about destruction of raptors in Altamont Pass wind turbines as well as an interest in documenting other species in the Alameda Creek watershed.
"There was no real database. The Christmas Bird Count was an opportunity to count these raptors," he said.
Last year, 94 volunteers in the circle tallied 155 species, including songbirds, blackbirds, woodpeckers, golden eagles and owls.
Most circles end their count days with a festive dinner at which volunteers can swap stories and report results.
"Some people have been doing this for five, 10 or 20 years and see each other only at the counts," Frost said.
Frost said that when a species name is called out at a dinner and no sightings are reported, there might be a moment of silence, but an announcement of an increase in sightings is greeted with applause.
The Christmas Bird Count "is very scientific, but it's also very cool," he said.
More information about local counts can be found at California
Audubon's website at www.ca.audubon.org.
--Bay City News Service