Families, school children and community groups throughout North America are expected to participate in the seventh annual Great Backyard Bird Count (GBBC), Feb. 13-16, to document the numbers and kinds of birds they see.

The event will create a continentwide "snapshot" of which bird species are where and in what numbers -- information critical to monitoring the health of populations, according to scientists at the Cornell Lab of Ornithology. The annual count was developed and is managed by the Cornell University laboratory and by the National Audubon Society. The count is sponsored, in part, by the Natural Resources Conservation Service, a division of the U.S. Department of Agriculture, and by the retail-store franchise Wild Birds Unlimited.

Participants simply keep track of the birds they see on any or all of the count days, then log their sightings into the BirdSource database at http://www.birdsource.org/gbbc .

Because the event is Internet-based, researchers and participants alike can see which birds are being reported where, all across the continent, says John Fitzpatrick, director of the Cornell Lab of Ornithology. "It's extremely satisfying to see that your observation is significant. These individual observations are critical to building a broad-scale database of North American bird populations, and the GBBC is the only count that provides a late-winter perspective," Fitzpatrick says.

Last winter, GBBC participants submitted some 50,000 checklists totaling more than four million birds of 512 species. The event, one of the largest citizen-science projects in the world, documented regional declines of the American crow that may be the result of West Nile virus in those regions. In addition to speedy results and easy-to-follow instructions, the GBBC Web site is packed with information about birds. This year's count encourages participants to become more "bird-friendly" in their day-to-day lives - everything from getting their families interested in birds to creating bird habitats in their backyards.

"Backyards are an important way to create greenways for birds between parks and wild areas," says Frank Gill, Audubon's director of science. "They allow for the cultivation of native plants and provide essential sanctuary to migratory and resident birds. Participating in projects such as the Great Backyard Bird Count gives people a first-hand view of how important bird-friendly backyards are to many bird species."

There is no fee or registration for GBBC. Participants without access to the Internet can try their local library, Internet café or other public online location. Many Wild Birds Unlimited stores accept reports. Questions should be addressed to the Cornell Lab of Ornithology at (800) 843-2473, or cornellbirds@cornell.edu .