Flight risk

Every autumn, as birds make their way south, they face a major obstacle to their flight path: windows.

Environment Canada estimates as many as 42 million birds die from collisions with windows every year — and that number could be even higher, according to new research.

Such accidents tend to peak in fall, when young birds that hatched in the boreal forest fly south for the first time.

On their journey, birds have difficulty distinguishing both reflective and transparent windows from the open air, particularly below the treeline.

Among a sample in the northeastern United States, just 40 per cent of birds injured in a window collision survived, a lower number than previously thought, according to a study published last month in the journal Plos One.

The researchers say that means more than one billion birds may die each year from flying into buildings in the U.S.

As researchers learn more about the devastating toll of bird-window collisions and how they can be prevented, some communities in Canada are making changes.

In Montreal, the borough of Saint-Laurent passed a bylaw this summer with new rules for large buildings.

Doris Potter, a retired bird lover and photographer, urged the Saint-Laurent borough government to make changes after she noticed several had died after crashing into a glass railing at her local library.

“I started to see this as a pattern,” she said.

“I know there's killing in nature, but this is very preventable and it's just very sad.”

The new rules for Saint-Laurent require building owners to reduce the reflectivity of the glass surface and make clear glass more visible by applying a film, visual markers or switching to frittered glass.

Alan DeSousa, the mayor of Saint-Laurent, acknowledged they won’t fix the problem altogether and described it as a “first step.”

“I don't have a magic wand that would make every building change across the board,” he said.

“If we can improve upon it over time, we will.”

But the rules do not apply to new and existing single-family homes, where research suggests the bulk of the bird fatalities occur.

DeSousa said the borough will also fix its own buildings over time, including the glass railing at the library.

“I think we need to build up education and awareness to be able to develop the right type of techniques and technology,” DeSousa said.

More than two dozen municipalities in Canada have some kind of rules to make their city more bird-safe, according to Nature Canada.

Richmond Hill, Ont., recently committed to changes at its own library and other city buildings.

Halifax has also taken strides, and recently passed a unanimous motion to research bird-friendly design standards.

Toronto was the first city in Canada to make changes with a bylaw in 2007. It requires bird-friendly windows — such as those with patterned markers — on new, larger commercial, industrial and residential buildings.

Kaitlin Brough, the volunteer co-ordinator of FLAP, a Canadian bird-protection charity, said the changes have proven effective for new buildings, but the city remains a hazard for birds.

“The biggest problem is buildings that are already there,” she said. “Those ones don’t have bird-safe markers at all.”

These 10 species-at-risk are common victims of window collisions in the Toronto area, according to FLAP.

Brough and her volunteers spend several mornings a week in the fall patrolling downtown Toronto, looking for birds.

They share their findings with building managers and try to persuade them to make their windows safer.

“On the mornings when it’s a really busy migration, it can be brutal,” she said. “There are mornings when I’ve picked up 50 birds. You hope that some are alive.”

Bird populations have declined in North America by roughly one-third since the 1970s.

Collisions with windows are a primary driver of that drop, along with habitat loss, pesticides and cats. Samuels said it’s hard to say which one is the leading cause.

“These threats are interacting and they are taking a toll at the same time,” said Brendon Samuels, a PhD student at Western University in London who studies bird-window collisions.

Last October, nearly 1,000 songbirds perished in a single night in Chicago, when they crashed into a lakeside convention centre. 

Experts said the collision was caused by a combination of prime migration conditions, rain and the exhibition hall’s large windows and bright lights.

Brough sees the effects of light pollution in downtown Toronto, as well. Birds are drawn to bright office towers during flight, she said, and even if they don’t crash into them, they remain at risk once they are in the city.

Single-family homes and smaller condos present their own risks, and overall account for more bird fatalities,  as they outnumber larger buildings.

“While we can pick up a lot of birds at a single tall building, if homeowners are having a couple of strikes a year, if you extrapolate that the total is way higher than at a commercial building,”  Brough said.

For homeowners and renters, there is an array of cheap and simple fixes available for windows, such as spaced-out dots that make them less reflective, said Samuels, who is also a researcher with FLAP.

“It adds a visual signal like, ‘Hey, birds, you can't fly through here,’ and you don't actually have to muck up the glass,” he said.

Samuels has been trying to persuade provincial governments to make changes to their building codes, so that new single-family and multi-family homes would also be required to comply.

“Ultimately what will save the most birds is having people engage with decision-makers in their government,” he said.

“If we're thinking about climate change and biodiversity and taking care of the environment, this is a very simple, inexpensive, easy thing that we can do.”

Autumn Jordan, who advocates for bird-friendly cities with Nature Canada, said, “Treating your windows at home, and just preventing one bird from colliding with one window, goes a long way in helping to protect our birds.”