Safer Flights

We’ve all heard that awful moment: We might be in our kitchen, brewing an early morning coffee, or working late on the 10th floor of an office building when suddenly a bird flies head-on into a window with a sickening thwack.

Buildings pose an enormous threat to birds; according to the U.S. Fish and Wildlife Service, window strikes kill up to 976 million a year. At UMD, faculty members and students are studying how to make buildings friendlier to birds and are surveying carcasses to count these deadly collisions on campus.

Structures and windows pose several dangers to fliers. Many birds migrating in the fall and spring—the deadliest times for the animals—use stars to navigate, flying at night or near dawn. “They’re disoriented by light pollution and end up being diverted toward cities, so when they land to rest at the end of the night, they’ve ended up in a potentially dangerous location,” said Stephanie Dalke, program manager at the School of Architecture, Planning and Preservation’s Environmental Finance Center. Birds are attracted to buildings that are lit up internally—like office buildings with lights left on overnight—and steer themselves directly into windows, often in the hour before sunrise.

Reflective windows are also a hazard. If a building is near trees, that vegetation could be mirrored in the window, giving birds the illusion that it’s safe to keep on flying.

“Fortunately, glass can be manufactured in a range of ways that make it visible” to birds, said Michael Ezban, a clinical assistant professor of architecture who’s taught students to design bird-friendly edifices. One option, he said, is fritted glass, made with lines or dots that act as a stop sign for birds.

Ultraviolet pigmentation, another option, can make glass visible to avians but not humans. The effect could be glass that appears hot pink to our feathered friends, indicating to them that it’s perilous to fly there. Ezban and his students have also explored ways in which designs can serve as habitat: In the United Kingdom, many architects utilize what are known as “swift boxes,” named after the endangered common swift. These are bricks that have been hollowed out, making them an ideal habitat for birds.

At UMD, Shannon Browne, a lecturer in the College of Agriculture and Natural Resources, leads student volunteers—often members of the university’s student chapter of the Wildlife Society—around campus in autumn and spring, tracking how many and what kind of birds have died. The data can be used to determine which buildings are most threatening to birds and may contain clues on how to prevent deaths.

“It hurts your heart a little bit, but we know that bird-gathering data and analysis is going to help,” she said. “So even though it’s sad at the moment, we know (this long-term project) is for a greater good.”