TORONTO -- In the shadow of the massive black towers of a bank's downtown Toronto headquarters was an almost indistinguishable puff of dark gray fluff on the sidewalk.
It was the body of a golden-crowned kinglet, an unlucky one, that had crashed into the iconic Toronto-Dominion Center building somewhere above.
There is no precise ranking of the world's most deadly cities for migratory birds, but Toronto is considered a top contender for the title. When a British nature documentary crew wanted to film birds killed by crashes into glass, Daniel Klem Jr., an ornithologist at Muhlenberg College in Allentown, Pa., who has been studying the issue for about 40 years, directed them to this city, where huge numbers of birds streaking through the skies one moment can be plummeting toward the concrete the next.
"They're getting killed everywhere and anywhere where there's even the smallest garage window," Mr. Klem said. "In the case of Toronto, perhaps because of the number of buildings and the number of birds, it's more dramatic."
So many birds hit the glass towers of Canada's most populous city that volunteers scour the ground of the financial district for them in the predawn darkness each morning. The group behind the bird patrol, the Fatal Light Awareness Program, known as FLAP, estimates that 1 million to 9 million birds die every year from collisions with buildings in the Toronto area. The group's founder once single-handedly recovered about 500 dead birds in one morning.
Though Toronto's buildings are particularly lethal, Mr. Klem was also quick to say that the city also leads North America when it comes to addressing the problem.
After years of conducting rescue and recovery missions and prodding the city to include bird safety in its design code for new buildings, FLAP has recently begun using the courts to help keep birds alive. It is participating in two legal cases using laws normally meant to protect migratory birds from hunting and industrial hazards to prosecute the owners of two particularly problematic buildings.
One especially effective, if unpopular, method of reducing the threat to birds is simply to cover the outside of windows up to the height of adjacent trees with the finely perforated plastic film often used to turn transit buses into rolling billboards, said Michael Mesure, who founded FLAP 19 years ago.
For new buildings, the solution can be as simple as etching patterns into its glass. A German glass company is also developing windows that it hopes can take advantage of the ability of birds to see ultraviolet light, by including warning patterns that are invisible to humans.
But even after nearly two decades of drawing attention to the problem, Mr. Mesure acknowledged that the threat to birds is still rarely considered by architects and developers. Along the morning search route was a hotel that was one of the last buildings approved before Toronto's new rules took effect. Its extensive use of irregularly shaped reflective glass will most likely make it "quite lethal to birds," Mr. Mesure said.