In Chapel Hill, an Iconic Tree Becomes a Rare Natural Roost for Migrating Chimney Swifts

It’s almost unnoticeable at first: A chittering sound here, a glimpse there. But within the span of half an hour, the sky over UNC-Chapel Hill’s McCorkle Place is full of them—thousands upon thousands of tiny, dark shapes descending on the quad, drowning out the last cicadas of summer with their own cacophony.

As the flying creatures circle a single tree at the center of the quad, even students stop to gawk.

“What’s going on?” one asks.

“Are they bats?” wonders another, a common mistake.

The mysterious creatures aren’t bats; they’re chimney swifts coming in to roost. The throngs of birds circle ever closer to the ground and then, one by one, funnel into the hollow center of the iconic Davie Poplar tree. The display is almost threatening, a tornado of birds. It’s no surprise it conjures Halloween-like images of swarming bats.

It’s a Planet Earth -level spectacle of nature, right on UNC’s campus.

Chimney swifts are small, insect-eating migratory birds that inhabit the East Coast during the summer before migrating back to South America for the winter. In Chapel Hill, they tend to linger from late March through October , but these mass roosting events do not start until August after they’ve raised their young.

From August through October, Triangle birders flock to swift viewing events in Durham, Raleigh, and now Chapel Hill. New Hope Bird Alliance (formerly New Hope Audubon) is hosting two “Swift Nights Out” at the Davie Poplar in conjunction with the Avian Society at UNC-Chapel Hill: one on September 18 and another on October 2.

Among the fastest fliers in the world, chimney swifts clock a rate of about sixty miles an hour. They spend the days flying before coming to roost, en masse, overnight.

Historically, swifts huddled in the hollows of trees like the Davie Poplar, where they roost in the thousands to conserve their body heat when the nights begin to grow colder. Then, the Europeans arrived to settle the Americas.

Deforestation and urbanization wiped out many of the trees suitable for roosting habitats.  Because chimney swifts are unable to perch like most birds and must cling to vertical surfaces to rest, the species resorted to nesting and roosting in chimneys—hence, their name.

The eradication of this species’s ancestral roosting sites is so complete that the Davie Poplar could very well be the only documented case in the state of swifts roosting in a tree, according to Barbara Driscoll, the New Hope Bird Alliance member who discovered the site.

“I’ve been trying to find any information about other trees, and nobody has any real data on other trees being used,” Driscoll says.

Driscoll has been counting swifts in downtown Chapel Hill since 2017. After a career with the Environmental Protection Agency (EPA), she’s been a member of the New Hope Bird Alliance since she and her husband Thomas moved to the Triangle in 1996. A former president of the group, she is now the chair of their conservation committee and co-chair of the bird-friendly habitat committee.

Counting the birds, which can number into the thousands, is no easy task—especially since the best time to do it is after sunset.

“Usually, you start counting by ones, and then 10s, and then 20s,” Driscoll says, “and then you’re estimating by kind of grouping them as they drop in.”

One night in September 2023, Driscoll was out on a swift count at Porthole Alley on Franklin Street, where chimney swifts had been known to roost in nearby chimneys. New Hope Bird Alliance had been concerned about a sudden drop in swift count numbers the previous year.

“I was really worried that just in general, the numbers were dropping. And I’d gone to do a count there, because that’s one of our typical count locations. And there were only three birds, and they just kind of flew around, and they flew off,” Driscoll says. “And I thought, well, that’s really weird, but I could still hear birds.”

Driscoll followed the sound of the birds to McCorkle Place. Thousands of the birds circled above the quad but she couldn’t figure out where they were going.

“I kept thinking, well, what chimney are they going into?” Driscoll remembers.

Then she realized that they weren’t circling a chimney at all: They were funneling into Davie Poplar. The tree, likely already more than a century old when the university’s cornerstone was laid in 1793, is a symbol of the university: legend has it that when the Davie Poplar falls, the university will fall with it.

This is precisely why the tulip poplar remains standing to serve as a place to rest for thousands of chimney swifts. Struck by lightning in 1873, any other tree would likely have been felled long ago.

“We’re just lucky that it’s the Davie Poplar,” Driscoll says.

The chimney swifts are lucky, too. Having lost access to their original tree roosts, chimney swifts are almost entirely reliant on human structures to roost through the cool fall nights and raise their chicks. While thousands of birds might share a chimney to roost, earlier on in the season only one pair will use a given chimney to nest and raise their young. With chimneys falling out of fashion due to the advent of central heating and air conditioning, chimney swifts are left with fewer and fewer viable places to raise their young.

This, along with the decline of insects, has led to a precipitous decline in chimney swift populations over the years. According to American Bird Conservancy’s “State of the Birds” report, the chimney swift is among an unfortunate list of bird species that have lost 50% of their population from 1970-2019 and are at risk of losing another 50% in the next 50 years.

Homeowners can mitigate the loss of chimney swift populations by leaving suitable chimneys made of brick or another rough surface uncapped for swifts to use year-round, or at least during the breeding season from mid-March through the summer.

Artificial towers can also be constructed in backyards or as projects with local churches, parks, schoolyards, and other public places. Turning off lights at night while chimney swifts and other summer migrants are passing through North Carolina from August through November also reduces the risk of window strikes, which can kill hundreds of swifts at a time. Durham, Raleigh, and Chapel Hill have all instituted “Lights Out” policies to protect migratory birds.

Haven Wiley, a professor of ecology and biology at UNC-Chapel Hill, has been compiling breeding bird surveys in the area for years. He says local chimney swift populations have dropped to about 40% of what they were 25 years ago.

The Davie Poplar has stood as a campus landmark for hundreds of years. If well taken care of, it could serve as a respite for the chimney swift for a few centuries more, giving visitors and students alike a chance to experience an incredible natural spectacle for generations to come.

“I think that most people have absolutely no idea about nature, and they kind of see it as something that’s over there, or you go to a state park and it’s there or a national park,” Driscoll says “But you know, nature is all around us all the time.”

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