They can resemble a flying cigar. The acrobatic aerial show of the chimney swift is like a choreographed tornado, at speeds up to 150 miles per hour.
"At some point, these birds collectively decide to go in. The mass of birds goes from tornado to just pouring into the chimney," said Jennie Gilraine, of Bethlehem.
A show Gilraine caught this past summer as thousands of chimney swifts landed in the chimney of the old Masonic Temple on Cherokee Street. The old building is now being demolished.
When migrating to and from South America, swifts rely on chimneys to roost. So, two weeks ago, Gilraine contacted the building's owner, John Noble.
"He said 'so I heard about these birds what's going on here?' So, I told him and the amazing thing was he was actually interested in these birds," she recalled.
Noble also owns the neighboring Wilbur Mansion and Hotel and is expanding on the temple's site. True to his name he agreed to keep the chimney, or at least build a new one if necessary, as part of his new project.
"The goal is to have these birds when they come back in spring ideally have something in place either the original or a replacement so it's ingrained in their traffic pattern," Noble said.
Head of the Lehigh Valley Audubon Society and Ornithologist Peter Saenger says the swift population has decreased 70% since the 1960s as chimneys have been capped or removed.
Due to their long claws, resting sites are limited. They return to the same area year after year and if their site is gone, they can be very vulnerable to the weather, Saenger said. He adds leaving the chimney will save tens of thousands of birds.
A Save the Swifts GoFundMe page has been set up.
"What Mr. Noble is doing is so incredibly unusual and incredibly good for the environment," he said.
"We have the opportunity to actually save something that has an impact on a species that up until two weeks ago I didn't know existed," Noble explained.
When renovation turns to conservation. A building plan that's taking flight.