24-Nov-14 – It is not easy being a migrating bird these days. Besides running a gauntlet of predators, pesticides, windmills, and violent weather, a bird’s biggest challenge in metropolitan areas comes from collisions with buildings.

Nesting spots have become condominiums, habitats have disappeared, and a once-open flight path is now filled with monumental roadblocks. “Tall buildings with dangerous glass and confusing lights have been present for only a short time in the generations of a bird’s evolutionary history,” says Annette Prince (left), director of Chicago Bird Collision Monitors. “These structures have appeared too quickly for a bird to adapt to them.”

Birds are hopelessly attracted to the light from skyscrapers and it confuses their navigational system. Flocks have been seen relentlessly circling buildings in downtown Chicago. They fly around and around, some crashing into the building and dying instantly while others finally tumble exhausted to the ground.

CBCM is an all-volunteer organization of more than 100 people who are out before dawn seven days a week during migration season, which runs from mid March to early June and from late August to mid November. Working on a grid system, they cross the city with the daunting task of rescuing injured birds and recording the impact locations of the dead ones.

Chicago is on the Mississippi Flyway, a bird migration route along the Mississippi River. Migrating birds have to pass between Lake Michigan on the east and open farmland on the west. Birds fly at night for a number of reasons – they do not overheat as easily, they don’t run into predators, but most importantly they can feed and rest during the day. Chicago, with its trees, shrubs, wetlands, ponds, and parks, has historically been a perfect habitat for them.

The biggest danger for birds in the city is glass, which they cannot see. After a long night’s flight, birds will easily fly into lighted glass as they try to enter the space behind it. (Right) FBI Regional Headquarters south of the Loop. When it opened in 2006, its large areas of glass were hazardous to birds. After consulting with CBCM, building management installed nets across this lobby, on the outside of the building. CBCM says it resulted in “a significant reduction” in bird collisions. Photo by David Seide.

Since 1998, the city’s Lights Out Chicago program has encouraged building managers in the Loop to modify their lighting during migrations. They are asked to turn off all exterior and decorative lighting from 11 p.m. to sunrise, and minimize interior and lobby lighting.

According to Prince, all of the major buildings in downtown Chicago were 100 percent compliant in 2004.

“We know that thousands of bird lives have been saved by this simple act of extinguishing unnecessary lighting,” she says. “Light reduction for darker skies benefits energy saving, human health, and bird welfare.”

If you have a plant by a window in your high-rise apartment, a bird may consider it a great place to land and rest, but will never imagine the glass in front of it. All you need to do is close a blind, Prince recommends.

“The hope of any bird-safe building is to minimize the appearance of a giant piece of glass.”

Architects today are using innovative building designs that eliminate the appearance of large, uninterrupted surfaces of transparent or reflective glass by creating “visual noise,” or a noticeable surface area into which birds are less likely to fly. An example of this is the Aqua tower by Studio Gang Architects.

(Above) Balconies on east side of Aqua. Photo by Steven Dahlman.

Hundreds of birds killed, injured on one day alone

Birds of a feather flock together, especially during migration, but a significant weather phenomenon will make them stop their journey and hunker down to wait it out. Sometimes migrations will stack up like jets over O’Hare, and when the weather clears, huge flocks will hit the sky together, creating a perfect feathered storm, which is what happened one day early this spring.

“We had 400 dead and 400 injured that day,” recalls CBCM monitor Ruth Kurczewski. “It started at sunrise. Suddenly, people were yelling, ‘There’s one, there’s one over there! There’s another one!’ It was mayhem. The exhausted volunteers were still finding birds at sunset.”

The worst part, says Prince, is that the best members of the species are indiscriminately taken down.

“In natural selection, the weak or injured are eliminated and the strong survive to procreate the species. But collisions with glass often kill the strongest, most valuable birds.”

 Website: Chicago Bird Collision Monitors