They swooped into town from Philadelphia or New York or maybe even Canada, hoovering up mosquitoes and dragonflies in flight.

To South America, they were headed! Where the insect-eatin’s good all winter. They bred in North America over the summer, so they wouldn’t even have that pressure when they made it south.

Chimney swifts, they’re called, because they roost in chimneys. They can’t see at night, so they tuck in each evening at sunset. It’s a sight to behold, a vortex of hundreds of black birds diving into a small hole at dusk. Once inside, they take little pieces of twigs and mix them with their saliva to create a cement-like adhesive that helps them stick to the wall.

Charlotte doesn’t have as many chimneys as it once did. Apartment buildings and condos have replaced many old homes, and it’s hard to find a resting place if you’re a traveling swift.

This particular colony checked into some dark cavity somewhere around Second Ward on or before the night of Tuesday, October 15. Left undisturbed, they’d have stayed until sunrise. But something happened just before 11 p.m. A noise in the hole, or someone sweeping them out. Whatever it was, they couldn’t roost there anymore, and they shot out, more than 300 birds, blind in the dark, going toward whatever light they could find.

When we’re kids and we wish that we can fly, it’s never without eyesight, is it? It’s easy to imagine coasting above the earth and looking down on everyone. Rarely do we consider the view of the visually impaired, flapping toward a blurry streak.

That night, the streak was the NASCAR Hall of Fame building, large-paneled windows wrapped around a bunch of old race cars.

The thumps started around 11 p.m. One after the other. Thump. Thump. Thump.

A security guard rushed outside. Another woman recorded video.

“I feel like this is the end of the world right now,” someone said as another chimney swift hit the glass, then fluttered and fell just on the other side of the window from Richard Petty’s blue No. 43 race car.

The video hit Facebook and immediately flung around the internet, a sign of end times for people who think like that.

Seeing the little black birds scattered on the ground in Charlotte, outside of a shrine to manmade machines those birds have to dodge daily, people wondered: Is this it?

For the chimney swifts, it’s a real question. Like many other bird species, they’re declining. The trouble isn’t usually windows, or even hot fireplaces, but something else that involves people: insecticides.

Swifts eat up to 12,000 mosquitoes a day, and when those mosquitoes are all filled up on chemicals, so are they. The chimney swift’s population has dropped more than 72 percent in the past 50 years.

And now here were 310 more. Charlotte-Mecklenburg Animal Control gathered the ones that looked to be alive and put them in dog crates. They’d do this for all but 13, which were obviously dead, leaving 297 in need of medical attention.

Keenan Freitas was at his home in Indian Trail when his phone rang: Hundreds of birds down in Uptown, coming your way. Freitas is the on-staff rehabilitation expert at the Carolina Waterfowl Rescue, a quirky little compound of feathers and goose poop just outside of the 485 loop.

Some animals come here after being picked up by strangers. Some are dropped off because owners can’t take them anymore. Others are hurt by cars or some other accident. Sometimes, animal control seizes exotic animals that shouldn’t be living in subdivisions. CWR doesn’t take cats and dogs, but a couple of donkeys named Jack and Diane live outside the bird area.

Inside, there’s a Muscovy duck named Bruiser and another named Godzilla. A trio of Dewlap geese travels together everywhere, their pillows dragging on the ground. The staff calls them Fat, Fatter, and Fattest. There’s Frankie the blind goose who comes when you call her name. Casper the Canada goose has no beak, but he still fosters other frightened Canada geese when they arrive. And the staff gives Frank, another white Muscovy, hugs before they leave each night.

It’s a loving place. Outside the front door is a small memorial to some of their favorite birds from years past. Local Girl Scout Troop 571 helps maintain the garden and the plastic headstones. There’s one for Mr. T, the “World’s Best Turkey,” who died in 2015 just shy of his fifth birthday; Clarence Mother Goose, who lived to be 18; and Pringles, Max, and Groucho, ages unknown.

In other words, it’s a fine place to be dropped off if you’re a dazed and bruised chimney swift.

Of the 297 that arrived, 92 were dead. Freitas and his team assessed the rest and devised medical plans. Ten more had to be euthanized right then. That left 195, about 66 percent of the colony, from this species of bird that’s been declining at a rate of more than 2 percent a year.

He told the animal control workers he’d take care of them, but they had to do one thing: call off the chicken seizure they had planned the next day.

Now the hard part: Chimney swifts eat every meal “on the wing,” meaning in the air. They’re hardly robins, hopping around on the ground and pecking at worms like unruly slobs. The staff and volunteers would have to hand-feed these birds.

Using tongs, they grabbed waterlogged mealworms one by one and tried to convince the sore songbirds to swallow.

Each swift had to be fed once every 30 minutes. It was close to 3 a.m. when the team settled into a rotation: dazed birds in one holding cell, fractured legs or wings in another, eye and head damage in another, fractured pelvis and spinal injuries in another.

“I’ve never heard of anything like this,” Freitas kept thinking or saying; he can’t remember which in the blur of it all. “I’ve heard of 10 or maybe 15 birds crashing into a window at one time.”

“Next to an oil spill, this is probably the craziest thing that can happen,” he says. “Now watch, we’ll get an oil spill tomorrow.”

At 4 a.m., everybody went to bed, humans and birds.

The next morning, the video from the NASCAR Hall really took off online. People posted screenshots of Hitchcock scenes. Others were reminded of bird incidents elsewhere: There was the blackbird invasion in Scotland Neck in eastern North Carolina in 1969 when the entire sky went dark, according to legend. And the great hawk pass of a couple of years ago, when 6,000 migrating hawks passed over the Blue Ridge Parkway near Sparta in a single seven-hour stretch.

By midday CNN fanned the story: “Over 300 Migrating Birds Smashed into the NASCAR Hall of Fame.”

Some viewers jumped to blame NASCAR, which had just finished a long weekend in Talladega, for leaving the lights on and inviting the carnage. The criticism grew so intense that the local visitors’ bureau released a two-paragraph statement that included a line: “We are willing to evaluate potential adjustments that we hope would mitigate future occurrences.”

“It’s not their fault,” Freitas tells me.

Other downtown businesses called the Audubon Society to ask how they could help in the future. They were telling on themselves. Each year in fall, the Audubon begs those same businesses to turn off their lights at night, to help migrating warblers pass through overnight. Few listen. Without lights, after all, how would people see those tall buildings?

The migrating birds’ worst nightmare became a marketing and awareness opportunity, even if everybody knew the chimney swift accident was a freak occurrence. Last year the Audubon Society found a little more than 95 birds dead from window crashes Uptown in the entire fall migration. This was 300 in a half-an-hour.

Thirty minutes away in Indian Trail, the bleary-eyed Carolina Waterfowl Rescue staff assessed the birds in daylight of Wednesday morning.

Five more had to be euthanized, leaving 190. But then the good news. One-hundred thirty-five could be released. The team loaded them up and took them to Freedom Park and watched them go.

With any luck, they’d be out of Charlotte before the first frost and on their way to South America again.

The remaining 55 needed more treatment. More food, every 30 minutes.

“Can you swallow it?” volunteer Jacque Junk said, holding a bird in her left hand and a tong pinching a mealworm in her right.

William Dixon, a pharmacist, was next to her.

“They don’t have a voice in our society,” he said, sliding the mealworm down the bird’s throat.

“Hey guys,” Freitas interrupted at one point, “we’re gonna have to keep our voices down. We’re seeing a lot of open-mouthed breathing in the birds.”

Open-mouthed breathing means the birds are stressed.

Just before 5 p.m., news crews showed up for live shots. One reporter asked to hold a bird, and Freitas agreed. The next asked his photographer to take a video of him feeding a swift for social media.

Freitas agreed and kept feeding, now with a syringe and soft food.

Outside the cage, Bruiser and Godzilla and Frank and Frankie and Casper and Fat and Fatter and Fattest and Casper the no-beaked Canada goose waddled around in the dirt. Four buzzards sat on the wildlife center’s rooftop.

The 55 remaining chimney swifts won’t be here long enough for names. They can’t stay past the first frost, which kills the insects, and the staff can’t feed them like this all winter. At about 6:30 p.m. Wednesday, as the sun set over the trees, the injury report looked like this:

Twenty-six had wing fractures; they’d probably make it.

Fourteen had head and eye trauma; they’d probably make it.

Four had leg fractures; they’d probably make it.

Eleven had pelvic and spinal injuries; they probably wouldn’t.

Back in Charlotte, the Audubon Society members went out to assess the chimney situation in this development-obsessed city. If you live in a home, they understand your desire to cap your chimney these days. But they’d ask that you’d consider an alternative — not capping your chimney.

And, of course, not using insecticides.

And turning off your lights.

And you know what would be a big help? Sending a donation to, or volunteering with, the Carolina Waterfowl Rescue, or joining the local Audubon Society. They still have a lot of birds to feed, and mealworms, you might be surprised to hear, are not free.

As darkness crept over the Charlotte area Wednesday evening, it had been 24 hours since the visiting colony of 300 or so unknown chimney swifts settled into some small hole somewhere near Second Ward.

Freitas sat in a chair in Indian Trail, feeding the birds and setting up heat lamps.

“I’ll probably be here all night,” he said.

At the same time, Audubon Society president Malia Kline and her members gathered outside of Big Ben Pub in South End, looking up at a chimney. Several others are worth monitoring each evening this time of year – one’s at Dilworth Elementary, another’s at Covenant Presbyterian.

If you look up and you’re lucky, you’ll see what Kline and her team saw Wednesday night: one hundred chimney swifts arrived at once, whirled around like a cloud against the pink sky, then dropped into the pub’s chimney, as if sucked out of the air until tomorrow.