Thousands of volunteers have a new assignment from the Cornell Lab of Ornithology – documenting the impact of West Nile virus while counting birds for the 2002-03 season of Project FeederWatch. This is the second time the volunteers have been asked to help scientists track an epidemic. Previously they kept notes on the spread of house finch conjunctivitis.

Since 1987 the Cornell lab has run the winter FeederWatch survey, asking bird enthusiasts of all ages, skill levels and backgrounds to record the numbers and kinds of birds that visit feeders across North America from November through early April. Cornell researchers then analyze the data to determine changes in population, distribution and abundance of some 100 species of birds.

Although crows and jays were among the first species known to be affected by West Nile virus, more than 110 species of birds have been infected, according to the Centers for Disease Control and Prevention (CDC). Ornithologists anticipate that bird enthusiasts will share their curiosity about what the rapid spread of West Nile virus will mean for North America's beloved feeder birds.

"Because Project FeederWatch has more than 15 years worth of data, we have a strong baseline to determine population changes in recent years that may be attributable to West Nile virus," says David Bonter, project leader for Project FeederWatch. "But to be able to make an accurate assessment, we need as many people as possible to tell us which bird species they are seeing at their feeders and in what numbers."

The CDC points out that the virus is transmitted to birds and to people by mosquitoes and that there is no risk to humans from casual contact with infected birds. Crows have been the most obvious avian victims of West Nile virus because of their size. But uncounted numbers of smaller birds also have succumbed to the virus, although their bodies are less frequently found by the general public or health authorities. Project FeederWatch hopes to document the virus's impact by comparing 2002-03 bird-count numbers with those from previous years.

The request is not unusual for veteran FeederWatchers. When a new strain of an established poultry disease was first detected in songbirds on the East Coast in the late 1980s, Project FeederWatch immediately asked participants across the continent to report birds showing signs of infection by the bacterium Mycoplasma gallisepticum : swollen, crusty eyes and blindness. The year-by-year, region-by-region spread of what became known as house finch eye disease was chronicled in great detail by FeederWatchers. Their reports helped scientists understand and analyze the dynamics of a bird disease that has become an epidemiological model for infections of many kinds, both in humans and animals.

Currently almost 17,000 citizen-scientists from across the United States and Canada are signed up for Project FeederWatch, and ornithologists at Cornell hope to add more in the coming winter season. Participants count birds for as long as they wish on selected days throughout the winter. They can submit their observations over the Internet or on mailed forms. Data are combined, and findings are published in scientific journals, magazines and on the lab's web site at http://www.birds.cornell.edu/ .

Project FeederWatch also was the first study to document cyclical changes in varied thrush abundance and the irruptive movements of the common redpoll. "These findings have been possible simply because so many bird-feeding enthusiasts are serving as our eyes and ears, since researchers can't be everywhere at once," says Wesley Hochachka, assistant director of Bird Population Studies at the Cornell lab. Adds Hochachka, who is a co-author of scientific reports that are based on FeederWatch findings: "Involving the public in our research is the best way to acquire vast amounts of data."

Participants in Project FeederWatch receive a research kit with a full-color feeder bird poster, a calendar and the FeederWatcher's Handbook containing bird-feeding tips and other useful information. They receive summaries of FeederWatch data and other findings published in the Lab's quarterly newsletter, "Birdscope." A $15 fee helps cover the cost of materials and data analysis.

The Cornell Lab of Ornithology is a nonprofit membership institution interpreting and conserving the Earth's biological diversity through research, education and citizen science focused on birds. For more information about Project FeederWatch or to sign up, call the Cornell Lab of Ornithology at (800) 843-2473 (Canadians, contact Bird Studies Canada at (888) 448-2473), or visit the FeederWatch web site at http://www.birds.cornell.edu/pfw.