The first-ever freestanding roosting tower built for Chimney Swifts in Canada saw its first inhabitants as the sun was setting on May 11.
“We have much to learn from it,” said Ally Manthorne with Bird Studies Canada.
Twenty-seven Chimney Swifts made their home in a new brick structure recently completed on what used to be the front lawn of the old Bridgetown Regional High School.
“This is very exciting news and I hope they continue to roost in the new chimney over the next few days and weeks,” said Manthorne in an email to the Annapolis Valley Register May 11.
Manthorne is the Maritime SwiftWatch coordinator with Bird Studies Canada with an office in Sackville, N.B. She received an email from a Bridgetown SwiftWatch volunteer who witnessed the 27 Chimney Swifts circle the chimney and then dive into the structure between 8:40 and 9 p.m.
The artificial roost was built by the Department of Transportation and Infrastructure Renewal as a condition of their federal Species at Risk permit to demolish the old chimney at BRHS.
“The Canadian Chimney Swift population has declined by 90 per cent since the 1960s, and Chimney Swifts are now listed as Endangered in Nova Scotia and Threatened nationally under the Species at Risk Act,” said Manthorne. “The drivers of this steep decline aren't fully understood but the large-scale loss of habitat -- both natural and human-made -- is thought to be one of the major threats to Chimney Swifts.”
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Bird Studies Canada and Mersey Tobeatic Research Institute are conducting weekly Chimney Swift counts at the new chimney in Bridgetown from May until September to study how the swifts take to their newly built roost.
Research biologist Natalie Thimot is with MTRI.
“I’m hoping to see some Chimney Swifts tonight, “ she said May 9 at the new chimney. She had a video camera and a stack of pamphlets on a picnic table in case members of the public came along. “We have a new chimney that was built here in Bridgetown and we’re monitoring the chimney to see whether swifts will move over from the old chimney to this newly built one.”
She admitted it might be a tiny bit early in the season. “Tonight is a really nice night though,” she said. “It’s warm. Skies are clear. So I’m hopeful.”
She said if the Chimney Swifts use the new chimney, then it would be great information since they’re at risk in Nova Scotia. “And this is something that could be used elsewhere,” she said. “If old chimneys are taken down then we know that we can build new ones and the swifts might use them.”
Two nights later the swifts arrived.
In a recent newsletter to Bridgetown SwiftWatch volunteers, Manthorne explained that Bird Studies Canada was involved throughout the process and had urged preservation of the old chimney as the best possible outcome for swifts as there are very few examples of successful roosting structures in North America.
“However, after demolition of the roost was approved and plans for a new structure were announced, we were invited to provide advice on the design of the new chimney,” Manthorne said. “We shared the valuable monitoring data collected by volunteers in Bridgetown in 2017 and 2018, provided information on characteristics of existing roosts in Canada, and advised on design features that we think will increase the chances of swifts adopting the structure, as well as provide opportunities to study the structure now or in the future.”
The new chimney has two data ports built into the structure to permit the installation of loggers or cameras, she said. An access hatch at the base will provide ventilation, drainage, and access for collecting guano, feathers, or other material for study.
That the first flight of Chimney Swifts seemed to have adopted the new $85,000 structure is a major relief to all involved.
“Once swifts discover a roost chimney they return to that roost year after year (or decade after decade), so maintaining these sites for Chimney Swifts is hugely important,” Manthorne said in an email interview. “The advance of heating and venting technology has rendered large brick stone chimneys more or less obsolete, and chimneys that no longer serve a purpose for humans are often capped or demolished.”
She said with the ongoing loss of both human-made and natural habitat, Chimney Swifts are likely to decline further in Nova Scotia and beyond unless steps are taken to address this, and other threats to Chimney Swifts.
Manthorne said Chimney Swifts seek out dark, sheltered structures that are thermally stable and protected from potential predators.
“Historically, large dead and decaying white pine, sugar maple, yellow birch and other trees with hollowed out centres would have provided this habitat,” she said. “However, very little old-growth forest remains on the landscape today.”
The large chimneys of churches, schools, factories and industrial buildings now support impressive flocks of roosting swifts during cold spring nights when the birds are returning from their winter home in South America, Manthorne said.
“A roost chimney like the BRHS structure serves as a sort of hub for the birds to gather overnight in large numbers, huddle together for warmth, and potentially find a mate” Manthorne said. “People may be surprised to learn that the BRHS is not full of nests. In fact, as the weather warms and insects become plentiful in early June, Chimney Swifts depart from the roost in search of smaller chimneys.”
Each nesting chimney only contains a single Chimney Swift nest, which is defended against intruders by the breeding pair, Manthorne explained.
“Birds that fail to find a mate or are too young to breed, remain at the roost chimney over the spring and summer, while pairs that successfully fledge chicks return to the roost in July and early August to prepare for the long migration south,” she said. “So the roost chimney serves an important purpose throughout the spring and summer months, until Chimney Swifts depart from the breeding grounds.”