When Birds and Glass Collide
Each migration season, millions of birds die in cities by crashing into buildings. Now a growing trend toward sustainable design could open the door to safer passage.
Two traits that make glass desirable as a building material--it's reflective and transparent--are also what make it so lethal to birds. Enticed by the reflection of sky or nearby foliage in mirrorlike panes, or tricked by a transparent sheet that looks like a way to an atrium inside a building, for example, birds will fly into the windows, knocking themselves out--sometimes fatally. These are deaths made more tragic by the journey taken to get there. "In the spring the birds you're seeing are the survivors," says Prince. "[They] went a thousand miles south, a thousand miles north, survived it all, and then hit a window.'"
Today there are more and more buildings with all-glass facades in avian airways. "In the 1950s and '60s all the high-rent buildings were made out of white brick," says Bruce Fowle, principal architect at FXFowle, a New York firm that is renovating the city's biggest bird killer, the Javits Center. "Now, in 2008, they're all being made out of solid glass." There's also a widespread push toward "sustainable" buildings designed to maximize performance and minimize operating costs. Perhaps somewhat ironically, some of the attributes that make a building sustainable--such as windows that reduce the need for interior lighting, or native vegetation planted on rooftops to lock in heat or cold--could contribute to bird mortality. More windows mean more opportunities for bird strikes, and for a bird, nearby habitat is like an oasis in the middle of a minefield.
But accounting for bird safety, some advocates argue, is part and parcel of green construction. "As we look at the evolution of sustainable design solutions, it can't just be about the passive components of the environment, like water and what happens with soil," says Michael Bongiorno of the Columbus, Ohio-based DesignGroup, which is incorporating bird-friendly design into Audubon Ohio's new environmental center in Columbus. "The fauna have to be part of the equation." Convincing the design community, developers, and their clients isn't always easy, however. Many people simply aren't aware. Birds that hit buildings at night or during the early morning hours often go unseen, scavenged from the ground by resident predators lurking nearby such as gulls and crows, swept up by sanitation crews, or power-washed out of sight. "They're mostly invisible to us, and we're never really confronted with the hundreds of millions of birds a year that are killed," says Karen Cotton, manager of the American Bird Conservancy's new Bird Collisions Campaign. "At most we maybe hear a thump on a window every once in a while, and we feel bad, and that's kind of the end of it."
Nor is there any silver bullet. A seemingly ideal fix would be a type of glass that's visible to birds but not humans. Glaswerke Arnold, a German company, advertises such a glass, called Ornilux; it has proved effective in laboratory testing, though it has not yet been subjected to field studies on the few buildings where it has been installed (one is at the Bronx Zoo). For his part, Klem isn't entirely convinced by Ornilux's technology, which involves coating the glass with strips that reflect and absorb ultraviolet (UV) light, a wavelength birds, but not humans, can detect. (He is currently conducting his own tests on UV light's effectiveness.)
Motivating the glass industry to make a product no one is demanding also poses a challenge. "It's a chicken-and-egg thing," says Jemssy Alvarez, an engineer at Guardian Glass, one of the world's biggest makers of fabricated glass. "I think the architectural community is saying, 'Well, we're not specifying this product, because it doesn't exist,' and here the technical community is saying, 'We're not building this product, because there's no market for it.' " Alvarez was forced to shelve an experimental glass he produced based on some of Klem's earlier research. "There's actually no technical reason whatsoever why we couldn't develop and commercialize the product," he says. "But I don't see any demands in the marketplace that give my leadership the assurances that they can make this investment wisely."