http://www.nytimes.com/2012/10/28/world/americas/casualties-of-torontos-urban-skies.html?hp&_r=0

TORONTO — In the shadow of the massive black towers of a bank’s downtown headquarters here was an almost indistinguishable puff of dark gray fluff on the sidewalk.

Ian Willms for The New York Times

A rescuer collects an injured white-breasted nuthatch. More Photos »

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 here, 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,” Professor 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. They carry paper bags and butterfly nets to rescue injured birds from the impending stampede of pedestrian feet or, all too often, to pick up the bodies of dead ones.

The group behind the bird patrol, the Fatal Light Awareness Program, known as FLAP, estimates that one million to nine million birds die every year from impact with buildings in the Toronto area. The group’s founder once single-handedly recovered about 500 dead birds in one morning.

Toronto’s modern skyline began to rise in the 1960s, giving it a high proportion of modern, glass-clad structures, forming a long wall along the northwestern shore of Lake Ontario. That barrier crosses several major migratory flight paths, the first large structures birds would encounter coming south from the northern wilderness.

Though those factors make Toronto’s buildings particularly lethal, Professor Klem was 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.

Briskly walking on a recent morning with a volunteer bird patrol, Michael Mesure, who founded FLAP 19 years ago, pointed out many examples of killer buildings. As he neared one particularly troublesome spot, on the eastern edge of the financial district, he pointed to a gaggle of sea gulls sitting in trees across the street from an office building. They were waiting, he said, to dine on the smaller birds maimed or killed by the building.

The building has a glass facade that disorients birds by reflecting the surrounding trees. Perceiving the reflection as habitat, birds zoom at it full throttle without regard for the danger.

The victims are largely songbirds. Perhaps because of familiarity, the urbanites of the bird world, like house sparrows, pigeons and gulls, are much less prone to crashing into glass, Professor Klem said.

All the birds collected by FLAP, dead or alive, go into paper bags. Though there were no survivors that recent morning, the merely stunned or frightened would have been released in a park near the shore of Lake Ontario. The injured would have been taken to one of two animal rehabilitation centers outside the city.