'Like a little tornado': Nesting season for endangered chimney swifts begins

If you hear a rustling sound in your chimney, it may be cause for celebration rather than worry.

And if, upon investigation, you find hundreds of little birds, well, you might have really hit the jackpot.

This is nesting season for the endangered chimney swift, a small bird that makes its home inside chimneys.

The birds, which have just returned to the Maritimes from their wintering spots in South America, are spending the next couple of weeks looking for a place to build a nest.

But before they pair off and find their own chimneys to nest in, they gather in flocks of hundreds and roost temporarily in so-called roosting chimneys.

Report sightings

Amy-Lee Kouwenberg, the project co-ordinator of Maritimes SwiftWatch, is encouraging people in the region to keep an eye out for chimney swifts and report any sightings.

"If you see a chimney swift, even if it's not going into a chimney, we're interested to know," she said.

Volunteers with Maritimes SwiftWatch, a conservation program of Bird Studies Canada, gathered Saturday at the McGowan Lake fish hatchery near Caledonia, N.S. There's a roosting chimney there — one of only 10 known roosting chimneys in Nova Scotia. Others are in Middleton, Wolfville, Mabou, Oxford, Falmouth and Truro.

Kouwenberg and the volunteers are part of a cross-country effort to track the numbers of chimney swifts. Between now and early June, bird enthusiasts aim to count the swifts as they funnel into roost chimneys.

"The swifts put on a wonderful show because ... they all swirled around our heads chittering and then they go almost like a little tornado into the roost chimney that's there," Kouwenberg said.

National count

But how do you count a "tornado" of little birds that disappear down a chimney in the blink of an eye?

"This is definitely challenging, and why we're always looking for more SwiftWatch volunteers, because the more eyes the better," Kouwenberg said.

Some volunteers use video cameras so they can watch the birds later at a slower speed and get a more accurate count. Another strategy is to estimate groups of 10 as they enter a chimney.

The final count at McGowan Lake was 218.

Chimney swifts are endangered in part because of habitat loss. Centuries ago, the birds used to roost in hollowed-out tree trunks, but later turned to chimneys. The birds can't get inside capped chimneys, and even metal liners make a chimney unsuitable habitat, as the birds use their claws and spiny tail to cling to vertical surfaces, and they're unable to grasp the metal and build a nest.

'Cigar with wings'

Kouwenberg said chimney swifts are commonly described as "a cigar with wings."

"They have sort of a narrow body and long wings," she said. "They really look ready for flight. They're great acrobats in the air — very much like a swallow, sort of swooping around."

Unlike similar birds such as tree swallows, chimney swifts don't have white markings.

They can also be identified by their chittering sound and by their flocking habits, as they flock together near dusk.

Chimney swifts are not able to perch on anything, so that's another distinguishing feature, Kouwenberg said.

If you've spotted a chimney swift, you can report the sighting to Bird Studies Canada.