ITHACA, N.Y. -- The Lab of Ornithology's Citizen Science Program at Cornell University is the largest program of its kind in the world. It puts 35,000 volunteers from around the world to work collecting data on the behavior and characteristics of birds.

"The Citizen Science Program, which is something we started here and named, has now matured into becoming a way of doing science on its own," said André Dhondt, the Edwin H. Morgens Professor of Ornithology at Cornell. Cornell, he notes, is the only university in the world that uses volunteers to collect data on a continental scale. The Lab of Ornithology's citizen science projects to date have more than two dozen scientific papers to its credit.

The idea of using volunteers to collect data began 14 years ago with a project to study birds in winter. Now, thousands of people of all ages, locations and experiences are involved in 11 major projects. Anyone can become a citizen scientist; all that is required is a passion to learn and study birds. Project FeederWatch, for example, has 16,000 citizen scientists who periodically count the birds that visit their feeders from November to April. During the Great Backyard Bird Count during four days in February, about 50,000 citizen scientists reported observing more than 6 million birds of 600 species in their backyards.

In the Urban Bird Studies program, many children are among participants counting specific birds while walking in a straight line. The data on the density of birds in different urban areas around the world help scientists in bird conservation. 

"I decided to try out the program as a way of showing children that they can be real scientists," said Alissa Daniels, the science program manager at the Boston Children's Museum, which is participating in the program for the second time this year, using primarily 6- to 12-year- olds. "The program teaches children how to make observations and collect data," said Daniels. "It encourages them to slow down and take a look at the world around them. Last year we watched gulls, and this year we are watching doves." 

For the Birdhouse Network, volunteers place birdhouses, or nest boxes, in their yards during the summer and monitor the birds nesting inside. 

"I've learned what boxes to install, how to build them, how to monitor them and what habitat requirements work for different species," said Michael Wiegand of Pearl, Idaho, who has been participating in the program for five years. "I've had successful fledging from various nesting boxes scattered about the yard, including northern saw-whet owls, a pair of kestrel fledgings, a house wren, a house sparrow and a pair of house finches." 

Participants record their data on the Lab of Ornithology's interactive Web site, where staff members can easily detect faulty data. 

"If you report you've seen 10 downy woodpeckers, we know it is not possible," Dhondt said, noting that about 5 percent of the data is deleted based on what the Cornell experts know about the characteristics and social behaviors of birds. "We know that woodpeckers are territorial. You'll never see more than two at the same time."

Once citizen scientists enter their data, they can check their entries, contact program staff if they have questions or read about the various projects in Birdscope, a quarterly newsletter summarizing data and answering problems or questions. 

"It is very important both for the scientific content of the data and for the educational value of participating in a research project that people have access to somebody at the lab," Dhondt pointed out. "The main idea is that by participating in research, you learn how research is done. You learn about the frustrations of research as well as the joys."

The Citizen Science Program continues to spread its wings around the world. For example, Raúl Festari, a teacher in Montevideo, Uruguay, works with his high school students on Project PigeonWatch, which seeks to discover why city pigeons have so many colors and how color plays a role in mating. "As an initial motivation, we let the students choose their scientific project," said Festari in an e-mail. "The fact that the students can work with a North American university like Cornell results in a special interest for them." 

Theresa D'Andrea is a junior English major in the College of Arts and Sciences.