Nature's air show awes nightly crowds below a Fredericton chimney

They arrive just after sunset near the leafy, downtown Fredericton neighbourhood. You can't miss them.

They bring tripods and cameras and binoculars and notebooks and group together in the parking lot outside the red brick building at 700 McLeod Ave.

To a person, they're looking skyward, watching for any signs of activity above the large chimney. From a distance, it looks like a scene in a UFO movie, where people gather and wait for the mother ship.

In fact, it's an almost equally awe-inspiring night of chimney-swift chasing in Fredericton.

I'd never seen a bird fly directly into a chimney in such high numbers like that, right? They're beautiful.- Andrea Addison

Fred Beairsto says the thrill never wears off. And he owns the building.

"Oh, it's amazing, it's just an amazing sight, " he says.

"When you first get here there are no birds, And then you'll see one bird come, and there will be clear blue sky, and then another one, and then 10, and then another dozen and then 20 and then a hundred, and then more and more."

Sometimes the number of birds flying in reaches2,000, according to some counts.

The birds made this their springtime haunt years ago, afterBeairstoswitched the building over to natural gas, and the chimney was no longer used.

"They're not going down the chimney," he says. "What they're doing is making a big circle around the chimney, a big circle,like hundreds of feet in diameter ... then somehow, one of them says, 'It's time to go in'. Then they start going in and it actually looks a little like smoke going back down the chimney."

Every night in late May and early June, the nightly spectacle draws small gatherings.

Some people, like Andrea Addison, show up just by fluke.

"My kids and I were driving by one day in the car, and we saw birds flying in what seemed to be a circle, over and over again in a circle, over the same spot," she says. "And I thought I saw one fly straight up and then straight down.

"I'd never seen a bird fly directly into a chimney in such high numbers like that right? They're beautiful."

Species at risk

The chimney at 700 McLeod is considered the largest roosting spot in the Maritimes for the tiny insect-eating bird from Peru, which makes its way to Canada to breed.

The bird's numbers have dropped by more than 95 per cent since the 1960s and it's now classed as a species at risk, according to Bird Studies Canada's Swift Watch program.

The Canadian government's species at risk registry estimates there are about 12,000 chimney swifts in Canada.

In the crowd of onlookers is Joe Nocera, a biologist and assistant professor of wildlife management at the University of New Brunswick.

Nocera fell for the chimney swift many years ago as an undergrad in Wolfville, N.S., where there was a big roost that people used to watch.

"Then later on after the PhD, I moved to Ontario, where I was the species-at-risk scientist, and once that species was listed it became an opportunity for me to study them. So I jumped at it and I've been studying them the past 10 years."

A home for chimney swift

Nocera says the chimney swift spends all of its waking hours in flight and eating insects. Its feet are designed to latch onto surfaces and at one time it roosted in the hollowed trunks of old growth forest.

With that disappearing, chimneys are the next best thing. But now chimneys, too, are disappearing, as more homeowners cap them on the advice of insurance companies, depriving the swifts of a home.

Nocera hopes the chimney at 700 McLeod can be preserved. It's not just a home but a potential source of research.

It's a sentiment Beairsto shares but at 78, he can't make any guarantees about the building.

"Well, that would be nice to save the chimney, but I have it on good authority that I'm not going to be on this earth forever, and so somebody else will own this some day, " he says.

"There are two types of people that would buy this. One would bring a bulldozer. And the other would try to manage the building better than I did probably. And I kind of hope it ends up being somebody who wants to keep the chimney."

Beairsto sayshe'd miss the crowds around the building if the chimney were to disappear, along with its status as a significant roosting site.

"I can hardly believe it actually, and to see all the people come here in the evening and get such joy out of it. It is a very spectacular sight and one that you just don't see often, where you see many, many animal or birds in one place."