To reduce bird-window collisions, Salt Lake Valley volunteers undertake a grim survey
As Chris Merritt moved into the new office space for the Utah State Historic Preservation Office — a building with big, reflective windows — he made a discovery.
“We started noticing piles of dead birds on the different aspects of the building,” he said.
Merritt, the state’s historic preservation officer, had been working from home during the pandemic. He put a bird feeder out to enjoy his home office a little more, and grew fond of the birds it attracted.
“And then seeing them being killed by the dozens by my office building just spurred me to want to do something,” he said.
Merritt began taking inventory of all the dead birds he found there – what species, where and when he found them.
“I'm an archeologist and so I'm a scientist.” So he decided “there needs to be some way of understanding where the impacts are occurring to then approach solutions to those impacts.”
Merritt reports that he has found about 30 to 40 dead birds since moving into the building in Millcreek last July.
The building has been around for decades, and so, “that is a significant impact that one building has had on a bird population of multiple species,” he said.
“If you drive up and down Highland Drive, there’s lots of other buildings built at that same period that have the same type of windows.”
Merritt concluded that his building represented “a microcosm of a much bigger problem.”
Across the U.S., between 365 million and nearly 988 million birds die each year from colliding with buildings – especially windows. That estimate comes from a 2014 study done by researchers from the Smithsonian Migratory Bird Center and the U.S. Fish and Wildlife Service.
Birds are susceptible to such collisions because “glass is a relatively new invention” relative to the existence of birds on the planet, explained Linda Johnson, outreach chair for Great Salt Lake Audubon and a member of its working group for bird-window collisions.
“They haven't evolved with [glass] and they don't understand that they need to avoid it,” she said.
The reflection from a commercial building’s windows often looks like a bird’s environment, Johnson said.
“They think, ‘OK, hey, I see trees. Let's go.’ And they crash into the window.”
Collisions often occur at night during migration seasons, added Cooper Farr, director of conservation at Tracy Aviary.
“When they fly over areas with a lot of light pollution – areas like the Salt Lake Valley – they get kind of drawn down into these areas,” she said. “They get kind of pulled off course, disoriented.”
To study the effect of light pollution on collisions, the aviary began conducting the Salt Lake Avian Collision Survey.
Twice each year, volunteers document all the dead birds they observe during the early morning hours in a specified area in downtown Salt Lake City.
“This is not one of our more fun projects,” Farr said. But the survey helps the aviary identify species that are particularly vulnerable to building collisions.
Farr said the survey has found “really high numbers” of hummingbirds, warblers and sparrows. That’s at least somewhat consistent with Merritt’s observations.
“Probably 60 to 70% of what I've noticed are hummingbirds – sometimes in pairs, maybe even breeding pairs,” he said.
Farr said the survey also helps to identify building characteristics that are especially problematic, as well as ‘hot spot’ buildings that see a high number of collisions.
According to the survey’s 2022 project report, six buildings accounted for just over half of all collisions observed downtown this year: 101 Tower, One Utah Center, Ken Garff Tower, 102 Tower, the Public Library and the Public Safety Building.
The aviary, in partnership with the bird-window collision working group, will then approach building owners and ask them to employ mitigation measures. So far, those conversations have yielded “limited success,” Farr said, though some buildings have committed to turning off their lights at night.
“I think generally people want to do good for the birds,” Farr said. “But if there's a cost in there — monetary or people doing extra work — it's really hard to motivate them to do it.”
Merritt, for his part, may be motivating change at his building. He reported that the state’s Division of Facilities and Construction Management has taken quotes on treating the 70-plus windows with “feather friendly” tape that leaves behind dots when it’s peeled away. This helps the birds differentiate between the windows and the reflected environment.
“The state's been pretty responsive in my experience, trying to work with our solution to fixing this,” he said. “But that's fixing our building, not the thousands of other buildings throughout the Salt Lake Valley that are killing all these poor birds.”