Birdwatchers ready to count 

Local birdwatchers are dusting off their binoculars and guidebooks and getting ready to count the birds in their neighborhoods, from the commonest of crows to the rarest of wrens.

The 10th annual Great Backyard Bird Count, organized by the Cornell Lab of Ornithology and the National Audubon Society, takes place Friday through Monday. Because the count is held in mid-February, it gives bird experts an opportunity to learn where migratory birds are congregating from year to year — which can help them track everything from West Nile virus patterns to the effects of global warming.

"It’s a really fun event that individuals can do alone or with their families," said Burlingame resident Carol Masterson, who usually treks to Washington Park, where she’s spotted rare woodpeckers and nuthatches.

Even locally, bird populations can vary from place to place. Foster City residents, for instance, are likely to see more ducks and water birds, Masterson said. And, over time, Peninsula bird lovers have taken note of important changes, such as a local increase in crows, which are more aggressive and can scare smaller birds away.

San Mateo participants counted Canada geese, mourning doves and rare fox sparrows in 2006, while those in Redwood City and South San Francisco spied hundreds of greater scaups (a species of duck). Twenty cedar waxwings were spotted in Burlingame, along with sparrows and finches.

On a national level, the bird count has revealed a 65 percent decline in crow populations, which experts attribute to the prevalence of West Nile virus, according to Pat Leonard, a researcher at Cornell University. But the survivors roost in large flocks, which could explain the apparent increase in San Mateo County.

After 10 years, the count has revealed some patterns that could indicate the effects of climate change.

"If it stays warmer, birds that normally go south will stay farther north, and we are already seeing some change," Leonard said. "Last year, hummingbirds stayed farther north rather than going to Mexico and South America, and some species are laying eggs a little sooner."

Researchers compare the February count with one performed each year at Christmas, which helps them track migration.

Last year’s count included checklists from 60,000 people nationwide, said Paul Green, director of citizen science for the National Audubon Society. To participate this year, visit

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Beth Winegarner

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