"You don't have to be a genius to do this kind of work," says wildlife biologist John Tautin. "But it's a tight market. There are very, very few jobs and a good number of people who are interested in doing this type of research."

Tautin is one of a handful of U.S. Fish and Wildlife Service employes who are experts on migratory birds. Since last summer, he has served as acting director of the agency's bird-banding program.

In the past 30 years, the unit -- based at the Patuxent National Wildlife Refuge and Research Center -- has played an increasingly important role researching the habits, psychology, social order and life span of migratory birds.

Tautin's office is responsible for certifying the qualifications of people who want to band birds and for coordinating information from people who have found such birds.

It's a specialized field. Bird banders generally have to serve an apprenticeship to ensure that they learn how to capture, band and release the birds safely.

"All of our applicants must have at least three references from ornithologists," Tautin said. Whenever a story is published about the program, he added, "school kids write, wanting to help us band birds. We have no choice but to say 'no,' unless they want to get some experience first."

There are about 2,500 active bird banders in the United States and 500 in Canada. The two countries cooperate on migratory-birds studies, and their certification processes are virtually identical.

Although the biologists at Patuxent do only a limited amount of research themselves, other parts of the Fish and Wildlife Service draw heavily on their studies to write the regulations that protect migratory birds -- especially those that are endangered or are hunted.

As an example, George Yonkle, who headed the program for a decade until earlier this year, cited efforts to bolster flocks of the endangered Aleutian Canada goose.

Foxes, imported from Russia in the 1800s, had preyed on the geese in their normal breeding ground in northern Canada. In the 1980s, the U.S. and Canadian governments removed the foxes from many islands there and put geese that had been bred in captivity back into their native environment. The newcomers quickly joined the remaining birds and readopted their traditional flyway pattern, wintering in California.

"But they ended up in some counties that didn't have bans on shooting the goose," Yonkle recalled. "so we were able to use the data gained from having banded the birds to ask the localities not to hunt the endangered goose. They agreed."

"You can't do an adequate job protecting the birds," he added, "if you don't know their habits."

Bird bands come in about 20 sizes, ranging from one the size of the necklace clasp that fits a hummingbird to one an inch across that fits the bald eagle and must be bolted shut.

After the birds are released, the research effort relies on the good will of hunters, bird watchers or people who simply find a dead bird by the side of the road.

Inscribed on all the bands are numbers indicating where the bird was banded and a simple request: AVISE BIRD BAND/WRITE WASHINGTON D.C., USA. The larger bands have room to include "FISH AND WILDLIFE SVC." Because many of the birds are spotted in Central and South America, the service uses the word "avise," which means "tell" in Spanish.

"Believe what you want about the U.S. Postal Service, but we think they do one heck of a job getting all of this mail here with no more address than that," Tautin said, flipping through a carton of more than 500 letters, most of them bearing only that address.

Clerks feed the information into a computer that plots where the birds were found. It then provides the latest information on the birds' migratory patterns.

Bands from North American birds have been collected as far away as Japan, South Africa and France. One was spotted on the leg of a peregrine falcon perched on the radio mast of a Soviet ship off Massachusetts.

Since the program began 62 years ago, more than 39 million bands have been attached, but only 2.2 million have been recovered. In recent years, about a million birds have been banded annually.

Sometimes, those who find a banded bird will cut off its leg -- with the band -- and ship it to Patuxent.

"We definitely don't want that, or the whole bird." Tautin said. "We just need to know exactly where the banded bird was."