Quick quiz question: What is the number one cause of mortality in wild birds, outside of old age?
It’s a trick question, really. Even scientists are still debating the answer.
That’s because scientists estimate that both house cats turned loose outdoors and window strikes kill more than a billion wild birds each year. Some recent studies estimate that cats kill between 1.4 and 3.7 billion birds a year, and collisions with buildings claim another billion a year in the United States alone.
But with numbers that high, why split cat hairs?
In days gone by, architects could claim ignorance in designing buildings. Even 30 years ago we didn’t know what we do now. Birds are made of blood and bone and feathers. Buildings are made of concrete and steel and increasingly more glass. When the two meet, birds lose.
In places like downtown Chicago or New York City, migrant birds — confused and drawn in by artificial lighting — collide with skyscrapers, particularly on cloudy spring or fall nights. But Chicago and New York aren’t the only places where concrete and glass kill.
Lynn Janik, greenhouse manager/animal care facilities manager at UW-Eau Claire started finding dead birds when she began working at Phillips Science Hall in 1999.
“Most window strikes seem to be outside the southeast glass stairwell of Phillips,” Janik said, “but I’ve also found dead birds from window collisions outside the main entrance of Phillips (north side) and also Centennial Hall (south and east sides).”
Here’s the thing; songbirds like warblers, thrushes and orioles migrate at night to avoid diurnal predators. But they fly high, not low, often thousands of feet above the ground.
UW-Eau Claire’s Phillips Hall is only four stories tall. The birds that Janik finds are not actively migrating. They’re taking a break from migration to forage for food nearer the ground. When surprised or startled, however, they fly beak-on into a window.
To a bird, large reflective glass looks like clear passage. It often augments the illusion by reflecting foliage or sky. Phillips Hall is adjacent to Putnam Park, where trees, not glass, offer safe refuge.
In today’s architectural world, there’s a new term: bird-safe. It means that buildings are built to specifications that reduce the threat to flying birds, day or night.
Humans love big plate glass windows that let in the view and the sunlight. But large windows, even on single-story homes, are toxic to birds.
Usain Bolt, the Olympic sprinter, can achieve land speeds of 23-plus miles per hour. An average human might be able to top 10 miles an hour. Even at that sub-Olympic-speed, running into a building would hurt.
When a half-ounce bird flying at a dozen miles per hour impacts glass, its beak is shoved violently back into its brain case.
Janik has found a wide variety of bird casualties outside campus buildings. Northern waterthrushes, purple finches, warblers, thrushes, even a belted kingfisher and a pileated woodpecker.
A 2014 study found that white-throated sparrow, dark-eyed junco, ovenbird and song sparrow were among the species most commonly killed by collisions with buildings. The study also reported that several species of national conservation concern seem to be especially vulnerable to collisions, birds such as the wood thrush, painted bunting and golden-winged, Canada, and Kentucky warblers.
A bird-safe design is conscientious about not only how tall the building is, but whether or not the lights are left on at night, which direction the building is facing, and how much of the building’s surface is glass.
Cities like Chicago, Toronto, and Milwaukee have instigated a “Lights Out” program. They turn the lights off in their skyscrapers on autumn evenings. And glass needn’t kill; there are ways to make it less reflective, or more visible to birds.
Janik tried applying decals to the Phillips stairwell in an attempt to prevent window strikes. But the stickers can’t keep up with the growing glass surfaces on campus. The most effective long-term solution is for architects to commit to bird-friendly at the blue-print stage.
“Bird populations are declining at an alarming rate,” said Janik. “The causes seem to be well established: climate change, habitat destruction — here in their summer home and in their winter home — pesticides, cats and window/building strikes. Some of these causes seem entirely preventable.”
UW-Eau Claire has yet to commit to a bird safe design. Centennial Hall is a glassy nightmare for birds, and there’s talk of replacing aged Phillips Hall with a new science building. What’s the plan?
“As the design process cannot begin until the project is enumerated in the 2019-21 state budget, we are not currently considering any design concepts,” said Mike Rindo, the university’s assistant chancellor for facilities and university relations. Rindo said that if and when the project moves forward, more conscientious construction is a possibility.
“Regarding bird friendly features in new buildings, each design process is unique and many different factors are considered, including sustainable and environmental, but I am not aware of any specifically bird related criteria,” he said. “Bottom line is that it is far too early in the process to speculate what design concepts would or would not be considered.”
With Democrats now in control of the House at the federal government level, there has once again been conservation legislation resurrected in Congress. In January, a Democrat and a Republican co-sponsored the Bird-Safe Buildings Act, H.R. 919, where it was referred to the House Committee on Transportation and Infrastructure. This bipartisan proposal is designed to reduce bird mortality by calling for federal buildings to incorporate bird-safe building materials, design features, and lighting.
That ethos and logos is taking shape at UW-Eau Claire as well.
“Last year we formed a committee, met with a student from sustainability and other campus and community folks to try to find a way to add stickers or tape to windows of Phillips Hall,” said Jan Stirm, associate professor of English at the university. “We tried to contact the facilities office on campus through email several times but never got a response.”
Stirm would like to see bird collision prevention as one of the starting points, along with other areas of sustainability, when new campus buildings are proposed.
“The campus community needs to require sustainability to be a priority in design,” she said.
Janik said she agrees.
“I am hoping when building plans are drawn up,” Janik said, “that appropriate glass will be used. “For example, bird-safe glass, with an ultraviolet reflective coating that can be seen by birds but not by us. This is a significant issue, and there’s lots of new technology that addresses it.”
The U.S. Fish and Wildlife Service has published a pamphlet with suggestions and examples, and architects are working on designing buildings to enhance sustainability and reduce bird collisions. To access it, visit fws.gov/migratorybirds/pdf/management/reducingbirdcollisions withbuildings.pdf.
Betchkal is a bird expert and a freelance writer who lives in Eau Claire.