Larry Schwitters, a fit 70-year-old in black Ray-Ban sunglasses, climbed a narrow, 40-foot ladder to the top of an old brick chimney on an elementary school. It was a sunny day in Monroe, Washington, and heat radiated off the flat, tar roof. Schwitters, uncertain whether or not the extension on the ladder was locking securely, jiggled it warily. Schwitters looked vulnerable so high in the air, even rigged to a climbing rope held by a friend. “Larry takes his life into his hands when he does this,” said the man holding the rope, Jim Rettig, president of a nearby Audubon Society chapter. “No, I take my life in your hands,” Schwitters called down.

Schwitters is a retired science teacher and former mountain climber who no longer thrills to heights. But he needed to repair a microphone he had fitted to the top of the chimney along with a video camera. When it’s working correctly, the equipment records the activity of birds called Vaux’s swifts. Like their cousins the chimney swifts, which live in the Eastern United States, these Western birds gather in huge groups inside old brick chimneys. The sounds and images from the equipment stream live over the Internet. The swift is Schwitters’ idée fixe. He spends at least 30 hours a each week on swift-related projects like this one.

No one knows exactly where Vaux’s (pronounced “vauks”) swifts spend the winter, or the details of their migration route. It’s not even known whether they migrate at night, as most birds do. But we do know the birds need chimneys. Schwitters has discovered that this one at Frank Wagner Elementary School might be the most important chimney in the region—more than 26,000 birds have been counted entering it in one evening.

Four years ago, this unused, 1939 chimney was a candidate for demolition as an earthquake hazard. Countless other old swift-sheltering chimneys, obsolete in buildings with modern heating systems, have already been lost to renovations or collapse. Schwitters and a growing band of others want to uncover more of the swifts’ secrets, and in the process stop more of the birds’ chimney stacks from falling.

On a busy night, the birds would be clinging to the bricks on the inside of the chimney in overlapping layers. But today Schwitters saw only one inside the stack. “Well, hello, birdie,” he piped.

Standing on the roof, I found a dead swift, remarkably intact, and scooped it up. Hold a soft, soot-brown Chaetura vauxi in your hand and you’ll feel how light it is—no heavier than a handful of cotton balls. You’ll also get a sense for what kind of flier it might be—the bird is mostly wings, two scimitar-shaped extensions that give loft to a stubby body and short, squared-off tail.

“They’re some of the most aerial of all birds,” says Charles Collins, a swift researcher and professor emeritus at California State University, Long Beach. “If they’re not feeding young, they’re probably on the wing all day.” In the air, they feed on insects and ballooning baby spiders. The birds’ high-flying ways may be one reason we know so little about this species.

The birds gather in huge numbers in the sky in the evening, swooping and whirling together on those elegant wings, then forming a gyre and plunging into the chimney for the night. “There are prettier birds, like the warblers, or bigger birds, like the great blue heron,” says Rettig. “But just to watch the swifts all together, well, it takes my breath away.”

Vaux’s swifts originally roosted and nested not in chimneys but in the hollow trunks and branches of old or dead trees. But those are few and far between on the modern migration route. Looking south from the Wagner School roof, there’s a bald patch on the foothills of the Cascade mountain range, a clear-cut in a spot where swifts might once have slept over. That’s why chimneys like these have become essential habitat.

Swifts are agile in the air, but not on land. They’re in the family Apodidae, a group of birds that can’t perch or walk—they can only cling. Since around the time of World War II, brick chimneys have been lined with metal or other materials to meet modern fire codes, and Vaux’s can’t use them. Chimneys older than that are generally crumbling, and therefore endangered.

The Monroe chimney may have hosted swifts, unnoticed, for years. “People who lived right there didn’t know about it,” Schwitters said. If they did, they thought the birds were some other species. An unidentified wag had even posted a sign on one of the school’s windows: “They’re not bats.”

Audubon members approached Schwitters and asked if he could help make the case for saving the chimney. “Just pulling your car up beside a school with a chimney on it looked pretty easy for this old guy,” he said. So he set to work counting the birds on evenings in spring and fall. His first visit in 2006 wasn’t especially promising—only 1,000 birds. But every night he returned—eventually with other people he’d recruited and trained in the art of counting birds by tens—he saw more. “We discovered that the numbers here dwarfed those at the Chapman School,” a more famous roosting site in Portland. “If this chimney was removed, the birds would have to roost elsewhere.” As he soon learned, there weren’t a lot of other elsewheres.

Schwitters, local Audubon chapters and school officials organized into a group called Vaux’s Happening to begin fund-raising for a hazard assessment and retrofit. They also held their first public event, a Swift’s Night Out. Audubon volunteers showed people what a swift’s wing looks like. Schwitters gave a presentation inside the school auditorium, and near the end of it someone threw open the door at the back of the auditorium and cried, “The swifts are here!” Outside, people gasped and squealed at the bird acrobatics, and cheered as they finally began circling the chimney, and then funneled in.

Schwitters decided to expand his range, calling bird organizations up and down the migration route, seeking more volunteers to look for other chimneys and count their swifts. He used Google Earth to identify likely chimneys in the bird’s range and e-mailed strangers nearby, asking if they’d be willing to go to a chimney some evening and look to see if little birds were gathering around it.

Collins, the swift professor in Long Beach, says the research Schwitters is aggregating is not only good for saving chimneys, it’s also useful science. “On a year to year basis, it’s a way of keeping an eye on whether or not there’s a dramatic decrease that might be an early warning that there’s something going wrong in their collective environment,” he said.

The project to save chimneys has already had several successes. Mark Sylbert, a painter and Hollywood art director who lives in a converted 1918 factory building in Los Angeles, learned about the project through a series of forwarded e-mails. Years ago he had stood with his wife and infant daughter on their fire escape and watched birds flying over another old brick building at sunset. The birds’ high-pitched twittering was often drowned out by city noise, but nothing overshadowed the visual drama as they swirled into a huge brick chimney. “It was so thick with birds it was staggering,” said Sylbert. When he heard about the Vaux’s Happening project Sylbert e-mailed Schwitters, sure that this was the same species. But Sylbert had lost track of the birds with a second kid and busy career. The building the birds had used had been converted to lofts, and the chimney knocked down. Schwitters convinced him to look for another likely chimney.

“To me that was just like a treasure hunt,” Sylbert said. He drove around downtown Los Angeles with his head tilted up at the sky. “It’s not really a safe activity,” he said. “I don’t recommend copying me.”

He found the birds, though, flying over City Hall at sunset. He followed them to the 12-story brick Chester Williams building and got out to watch them. An article about it ended up in the Los Angeles Times, and Jeff Chapman of the Audubon Society in Los Angeles has gone on to organize events for public school kids to come out and see the Chester Williams Vaux’s. Sylbert compares the event to taking his kids on a whale watch expedition. “But you have to have money to go out and whale-watch—this is something that brings itself right into the core of L.A."

Other volunteers have similar stories of finding sites in San Diego, San Francisco and elsewhere along the migration route. But few locations so far have been protected. Out of the 12 biggest roost sites Schwitters has identified, five have been torn down or capped since the study began. Several others, while not under immediate threat, could be torn down at any time.

But not the chimney in Monroe. Last fall, repairs there were finally completed. As it turned out, the stack didn’t need rebuilding, only stabilizing with angle iron, brackets on all four corners of the chimney which extend up its length. There was even money left for a kiosk in front of the school, where the community and Vaux’s watchers can learn more about the birds’ lives. “In fact, the chimney has added value to the school,” said Ken Hoover, superintendent of Monroe public schools.

“I’ve traveled far to watch birds,” said Christopher Adler, a music professor in San Diego who helped find a roost site in a nearby church chimney. “Thailand, Laos, Cambodia. But seeing those 10,000 Vaux’s in one night,” he said. “I’ve really never seen anything like that. Every direction I looked, they were as far as the eyes could see.”

If Larry Schwitters gets his way, more and more people will have that thrill. “We took him on to help save the chimney,” said Mike Blackbird, president of the Pilchuck Audubon society, at a recent celebration of the Monroe chimney win. “He went on to try to save the species.”