Birds Fly into Windows

Bird-killers abound, but the top assassins are not your usual suspects.

Dr. Daniel Klem Jr., a Professor of Ornithology Conservation Biology at Muhlenberg College,³ estimates that glass-lined skyscrapers are responsible for the death of 200 birds each day.⁴ In the United States alone, ornithologists estimate that between 97 million and 975 million birds are killed every year due to collisions with windows.⁵ Dr. Klem has identified over 270 different species of birds that have collided with glass windows or plastic in the U.S.,⁶ with 866 bird species in total recorded as having collided into windows worldwide.⁷

The Glass Problem
Glass is a danger to birds primarily due to its reflectivity. Birds often see escape routes or “intruders” mirrored in reflective glass. The speed and force of the impact can cause instant death or fatal injury—traumas such as brain hemorrhages or other internal bleeding.⁸ Transparent glass is also hazardous.⁹ Birds often collide into unseen windows en route to some target on the other side of the pane.

Another major problem are the lights that building operators leave on overnight. Michael Mesure, an activist in Toronto, runs a group called FLAP — the Fatal Light Awareness Program.¹⁰ FLAP focuses on convincing big buildings to turn out the lights at night because they attract migrating birds.¹¹ As author Anne Matthews describes it (in one of my favorite nature articles of all time):

The bright lights of office towers seem to short-circuit the natural navigational abilities of birds in flight. Sophisticated city breeds like pigeons and sparrows stay calm when they see a city skyline at night. Songbirds travel late, when air currents are calmest, and steer by the stars. But Manhattan buildings can be a quarter-mile high. Migrants see lights directly in their flight path, follow them trustingly, then circle the Chrysler Building or the World Trade Center, mesmerized, until exhaustion claims them.¹²

Glass Hazard Solutions
The National Audubon Society offers several suggestions to help homeowners safeguard their feathered neighbors, including:

1. Move bird feeders, bird baths, and perches to within 3 feet of your windows — Birds often fly into windows after being startled off of a feeder. When feeders are within three feet of windows, birds can’t fly into them fast enough to get hurt.
2. Pull the drapes — Light colored window coverings help to decrease the reflectivity and transparency of windows.
3. Place decals or strings on the outside of windows — This breaks up reflections in the glass.
4. Use screens, films or bird safe glass.
5. Tilt windows — Tilted windows show the reflection of the ground, not perceived escape routes or enemies.
6. Take care when installing new landscaping — Consider placing trees, shrubs, water fountains, and features that attract birds far away from windows.¹⁴

Window companies are starting to take some initiative to address the problem as well. A German company called Arnold Glas makes Ornilux, a glass inspired by the designs of spider webs. A special ultraviolet reflective coating makes the webbed pattern of the glass visible to birds (birds see well in the ultraviolet range), but invisible for humans.¹⁵ According to the Max Planck Institute for Ornithology, the coating reduces bird strikes by an estimated 75 percent.¹⁶

In addition to these widely adoptable solutions for residential dwellers, building designers are also starting to integrate bird-friendly strategies into larger commercial building projects. For example, the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED) system awards points for including bird safety considerations in building design.¹⁸ Moreover, some cities in the United States and Canada either have, or may soon have, new building codes that require bird-friendly materials.

Guy Maxwell, an architect in Manhattan, is one of the leaders in the field of designing bird-friendly commercial buildings. He told an NPR reporter, “the notion that a building that we’ve built is causing harm is really troubling to me.” Inspired by his love of birds, Maxwell is trying out some new bird-friendly concepts at Vassar College, in Poughkeepsie, New York. Vassar’s new science building will stretch across a stream in the woods, “right in the middle of an area where we know there will be birds flying, so we had to do something about it,” he says. Maxwell plans to incorporate “fritted” glass into the design. A frit is a run of thin ceramic embedded in or on glass. When set in rows that are no wider than two inches apart horizontally or four inches apart vertically, the pattern deters birds. Although corporations and building managers have traditionally shied away from such features, some are coming around now that glass designers are making their products more aesthetically pleasing.²¹ After all, patterned glass will always be more attractive than happening upon a fallen songbird.