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Maintaining a habitat for NPD’s Chimney Swift population

Chimney Swifts, as their name suggests, are known to nest and roost in chimneys and other hollow manmade structures. These small birds, with a unique cigar shape, are migratory insectivores, returning each spring to breed in Canada and the United States, and flying down to South America in the fall.

According to the COSEWIC Assessment and Status Report on the Chimney Swift, the population has decreased by 95 per cent since 1968, qualifying the bird as a Species at Risk. The cause of the decline is thought to be brought about by a combination of changing weather patterns, food scarcity and a reduction in roosting habitat.

Unpaired birds and juveniles roost communally in larger structures with the number of individuals growing during the course of the season as fledglings and parents join the group. A single stack can provide a home to thousands of birds. Between the Maritimes, Quebec and Ontario, 750 roosts have been identified, one of which is at the Nuclear Power Demonstration (NPD) reactor in Rolphton.

What attracts the Chimney Swifts to NPD?

Ontario Hydro operated the NPD reactor, mostly as a training facility for generations of CANDU® reactor engineers and operators, for a quarter of a century – from 1962 until 1987. After reactor shutdown, the ventilation stack became home to a large number of Chimney Swifts who roost annually in the chimney-like structure. The NPD ventilation stack is now an important stop-over during the spring migration and the number of Chimney Swifts can reach more than 2000 birds.

In 2010, biologists from CNL’s Environmental Protection Program began an evening roost counts program annually to track the trend in the numbers of Chimney Swifts inhabiting NPD’s ventilation stack. Every year, as a part of monitoring protected species, CNL counts the roosting Swifts as they enter the ventilation stack at sunset. In a way, the Chimney Swifts have chosen an ideal host to investigate their behaviour. Research into this bird species is an important step to understanding the best conservation methods.

Habitat is also an important part of conservation. With the preparations for the final decommissioning phase for NPD underway, CNL had to make a decision about the Chimney Swift habitat. After hosting a workshop to deliberate over proposed options, including building a new-engineered habitat, CNL decided to keep the existing ventilation stack as a home for the Chimney Swifts. CNL came to this decision with valuable input from knowledgeable and interested groups, including Environment and Climate Change Canada, the Shawville Roost Initiative, Bird Studies Canada Ontario SwiftWatch, the Canadian Nuclear Safety Commission, Trent University, the Ontario Ministry of Natural Resources and Forestry, and Brock University.

Retaining the ventilation stack as a habitat will ensure minimal disruption for the Chimney Swift population that migrate to this stack. By 2020, the anticipated year for completion of NPD’s decommissioning, the Chimney Swifts will be the sole inhabitants of the NPD site.

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