See a swoop of swifts? Here's why a group of birders is trying to count them all

At dusk in September, Winifred Wake can often be found sitting on a lawn chair in London, Ont., watching hundreds of birds circle chimneys.

She's counting chimney swifts, threatened tiny black birds that pass through southwestern Ontario during their fall migration journey to Central and South America.

"I think they're a fascinating part of nature," she said. "This time of year, hundreds will spend nights together in old unlined brick chimneys."

Wake is a member of Nature London, a group of 50 volunteers who work to monitor and protect the birds and other species.

The chimney swift is of great interest, as their populations have declined by more than 90 per cent since 1970, according to Birds Canada, landing them on the federal Species at Risk Act list.

Nature London, which is affiliated with Ontario Nature and Nature Canada, monitors 18 chimneys in the city, keeping track of swift populations from year to year.

"They're continuing to decline, and it's important we provide protection for birds," said Wake.

"They're very much dependent on the goodwill of humans to preserve some of these chimneys for them to have habitat to nest in or to rest for the night and roost. 

"We don't have as many or any old growth forests with hollow trees where they could nest or roost anymore, so that habitat is gone."

Each bird also eats about 1,000 insects a day, but with insect population in decline, habitat loss and extreme weather, their food source is dwindling. 

Earlier this week, volunteers counted over 300 swifts at a warehouse sporting chimneys in south London, while another 300 were counted near the downtown. The numbers change day to day as new birds arrive and others continue to migrate.

London has earned a reputation as a hub for chimney swift knowledge and advocacy.

In the past two weeks, wildlife rescues from Quebec and eastern Ontario came to the city to release orphaned chimney swifts with Nature London volunteers.

Connie Black drove to London from north of Kingston, Ont., to release seven orphaned chimney swifts into a group of roosting swifts. She runs a home-based bird rescue, Destined to Fly, focusing on species at risk.