Room for 2,400? Chimney swifts check into a Fredericton chimney

CBC

31-05-2025

You might not want to live in a chimney, but for a chimney swift, it's the ideal place to rest — and a Fredericton chimney was a recent pit stop for more than 2,400 of the tiny birds.
"They're stopping at these roost chimneys along the way, almost like hotels on a road trip," said Allison Manthorne, an aerial insectivore conservation strategist with Birds Canada.
But while chimney swifts like to warm up and nest in chimneys, it isn't necessarily common to see 2,400 fly into a single chimney anymore, Manthorne said.
"The national population of chimney swifts has declined by about 90 per cent since the 1970s," she said.
This is why counts like the Fredericton one are a good sign for the population.
A chimney swift is most likely to be found high up in the sky, Manthorne said. From below, the bird appears as a boomerang-shaped, black silhouette.
Their legs are short but they have relatively huge feet, helping them cling vertically to surfaces.
Nationally and in New Brunswick, the species is threatened.
Birds Canada has a national roost monitoring-program that puts staff and volunteers at roost sites to count the birds entering particular chimneys. Manthorne said this helps the group get a sense of whether the population is increasing or decreasing.
Last weekend, Emma Lennox, a Birds Canada technician, was at the Fredericton roost near Queen's Square as part of the national count. She took a video so the organization could play it back in slow motion and get an accurate count.
WATCH | Birds make pit stop at Fredericton chimney:
How many swifts can fit in a chimney? At least 2,400!
4 days ago
Duration 2:15
A technician with Birds Canada captured more than 2,400 chimney swifts flying into a Fredericton chimney on May 25.
That video captured more than 2,400 swifts entering the chimney.
"That is only the second highest number or total of chimney swifts that we've counted at that roost," Manthorne said.
"The last time we counted anything close to the 2,400 … was in 2018 and the record was 2,700 birds.
"All of those birds are funnelling into that one chimney, and they're roosting together overnight. Now this happens across the Maritimes and across … Eastern Canada, but not really anywhere close to those numbers."
Chimney swifts are relatively small birds, about 12 to 15 centimetres long, with a wingspan of only about 30 centimetres. Once they get into the chimney, Manthorne said as the night goes on, they cuddle closer together, helping them to regulate their temperatures and conserve energy.
"They can pack in so close that it's almost like ... house shingles," she said.
"Occasionally, you'll see that kind of band of swifts in their little snuggle puddle ... go up or down the wall based on what the temperature is."
Manthorne said the birds fly to the region from South America and stop at roost chimneys along the way. When they reach their destination, they meet up with their partner and, once the weather is good enough, each pair will find its own chimney to nest in.
She said the best chimneys are unlined and in their original condition, and it's important to preserve the chimneys that do exist. Masonry, stone or concrete chimneys aren't really being built anymore.
"If you are lucky enough to have a nesting pair in your chimney, you could expect year after year that that same pair will come back, and it's likely that their offspring will then come back in generations in the future."
And because the birds are a threatened species, Manthorne said, it's also crucial to not harm them if they roost in your chimney.
It's a good idea to close your damper once you've stopped heating for the season, so the birds can't get inside.
And if your chimney is lined with metal, it's a good idea to have a cap on it because often the birds, or other animals, will go down the chimney and can't get out.
Most of the time though, people don't even know if they have swifts in their chimney.
"They're really good house guests," Manthorne said.