In a little more than two months, with throngs of people in Ottawa for Canada Day celebrations, the National Arts Centre is expected to unveil its new façade, a glittering transparent sheath of bird-safe glass that’s meant to resurrect the reputation of a building long derided for its brutalist architectural style.

But a local bird advocacy group in Ottawa is skeptical about how effective that glass will be in preventing birds from colliding with it. “I know there was an attempt to make it bird-friendly,” says Anouk Hoedeman, founder of Safe Wings Ottawa. “But it’s not as bird-friendly as I would like to see.”

The majority of the new glass on the building has a ceramic pattern called a frit baked into it, which is meant to be visible to birds and thus deter them from flying into the glass. But Hoedeman says the frits are spaced too far apart to be effective. A post she wrote about the building says that the guidelines that the architects adopted are outdated and do not reflect the current suggestions for bird-safe glass. The glass addition also includes a tower, which doesn’t have a frit pattern but will house a large LED display, which should mitigate collisions.

Because the city of Ottawa has no guidelines or requirements to make buildings safe for birds, architects had to look elsewhere for recommendations. They used the city of Toronto’s mandatory bird-safe guidelines for how to best prevent birds from crashing into the glass.

“If you make a glass building, there’s a responsibility to environmental concerns, and that’s one of them. Even though Ottawa doesn’t have a standard, it’s only prudent. We wanted to be forward thinking on it,” says Jennifer Mallard, the lead architect on the project. “It’s an evolving science. We are still in the test period to see what mitigations work.”

“We think we’ve struck a balance between the environment and the concerns about the bird-friendly building,” says Carl Martin, a spokesperson for the National Arts Centre, adding that the centre will monitor the building to see what happens once the renovation is complete.

Hoedeman remains unconvinced but hopeful. “I’d love to be proven wrong,” she says, “and to find that there aren’t any collisions.”

Safe Wings Ottawa estimates that 250,000 birds died after hitting windows in the city in 2016. Fatal Light Awareness Program Canada, an organization that works to safeguard migratory birds in urban environments, estimates that across North America the number of migrating birds killed annually in collisions with buildings ranges from 100 million to one billion birds.