A flock of 398 birds hit a high-rise one night in Galveston Texas in May 2017, when a deadly combination of a storm and lights from a high-rise building disoriented the birds. It was devastating for such a large number of birds, nearly all migrating warblers already threatened by habitat loss and climate change, to die en-route to their spring nesting grounds.
The Galveston incident brought national attention to the increasing risk of city high-rises, lights, and reflective windows for birds. Window strikes are killing up to 988 million birds every year across the U.S., according to a 2014 study in the ornithological journal Condor. There are steps that can be taken to lessen the risk, but the gravity of this problem is still going largely unnoticed.
Heidi Trudell and Alice Elliott, coordinators for Washtenaw Audubon Safe Passage (WSP) are working to change this. Trudell and Elliott teamed up in 2016 to take the program, which began in 2006 to increase awareness of the hazards of high-rise buildings killing millions of birds, to the next level as a monitoring-based project. They began documenting bird mortality, and to date, with the help of at least ten more volunteers they’ve collected two years of research data.
The Metro Detroit area and Washtenaw County are within the intersection of two migration flyways—the Atlantic and Mississippi—making the location a ‘hot spot’ for migratory birds and high-risk for window strikes.
Trudell and Elliott volunteer more than ten hours weekly from March 15 through November 1. With a growing team of volunteers they are now able to cover between twenty-five to thirty buildings in Ypsilanti and Ann Arbor, including EMU and WCC’s campuses, North Campus at UM, Ypsilanti District Library, and the Ypsilanti courthouse.
Millions of songbirds and shorebirds migrate through the Great Lakes, travelling to the Boreal and as far north as the Arctic passing through urban areas as they head north, many following Lake Huron’s shoreline. Most songbirds migrate at night using the stars to navigate, and lights in the cities and suburbs lure them off course. Fall migration is the highest risk because of the larger populations of both adults and many recently fledged juveniles migrating south.
Collecting dead birds is not the usual or preferred way birdwatchers begin their day, but Trudell and Elliott emphasize that data documenting location, architecture, season, species, and overall mortality is invaluable for risk and mitigation analysis to reduce unnecessary bird deaths. This is urgent in a world where we’re already losing so many birds to multiple environmental threats.
On a typical spring morning, Trudell will try to check the courthouse building on her way to work. She covers ten buildings on EMU’s campus twice a week, either splitting the route into two parts or dedicating one full evening to it, and again checks it on the weekend. No matter how stretched, she finds time to monitor EMU’s library. “We try to keep the EMU library at 2+ surveys per week because it’s such a problem.” She coordinates with two volunteers to make sure the Ypsilanti District Library is checked every Monday through Friday during migration. Its windows overlook nature offering peaceful serenity, but it’s also a deadly magnet for birds that see a reflection of trees and landscape and fly right into the glass.
Elliott monitors three buildings at WCC five to six times per week and that varies between three and six hours, squeezing this in between UM graduate courses and work. She usually monitors after classes in late afternoon or even at night when necessary, “that’s when the flashlight comes out!”
Ruby throated hummingbirds are killed most often says Trudell, showing fourteen dead from just one Ypsilanti building over 1.5 years of data collection. That’s almost 4 times greater than American robins found at the same building, and robins fly low putting them at higher risk of hitting low-rise buildings. Even common mourning doves were about one-half of the hummingbirds’ mortality. “I find so many ruby throated hummingbirds. They are at the unequivocal top of the strike list for low-rise buildings and diurnal (daytime) strikes.”
Because high-rises with reflective glass and lights are especially deadly. Elliott explains they need to be checked for dead birds at daybreak. “High-rises tend to have a lot of foot traffic as they’re usually located in the middle of a city, and so you have to get out there pretty early to collect the bodies before they get swept away or stepped on.” Dead (and stunned) birds will be quickly taken by predators.
Nocturnal migrating songbirds like warblers, orioles, and tanagers collide with office buildings when disoriented by lights. Storms bring greater risk as in Galveston because birds decrease flying altitude. And even if they don’t collide with windows, migrants lost in the cities are at risk of dying from exhaustion, lack of food, and predators.
Sixteen warbler species have already been documented through WSP, some of the more worrisome fatalities since many are already threatened. Warbler collisions at just one building include blackpoll, Nashville, yellow-rumped, Tennessee, magnolia, black-throated blue, black-throated green, and chestnut-sided. Trudell’s ‘freezer list’ (as she describes her specimens now being used for science) of window collisions for WSP is now at least fifty-three species since September 2015. Rare finds have been golden-crowned kinglet, gray catbird, oven bird, scarlet tanager, red-eyed vireo, indigo bunting, song sparrow, Swainson’s thrush, yellow-billed cuckoo, and familiar backyard species like cedar waxwing, Northern flicker, and red-bellied woodpecker.
Prevention is the core mission of Safe Passage. Trudell meets with architects and facility managers to consult on mitigation and design strategies for bird-safe buildings. Turning off lights reduces bird mortality and saves electricity. “For high-rise buildings or any building over five floors, turning off non-essential internal lights from ten or eleven p.m. until 6 a.m. year-around, and especially if decorative exterior lighting is turned off as well, would be tremendous.” It’s a win-win solution.
Unnecessary lobby and atrium lighting can be minimized at night, and night staff should turn on lights in individual rooms only as needed. If certain lights must be left on, use curtains and blinds to block light.
Plants are a hazard when visible through windows because birds see a false natural landscape and try to fly-through it, hitting the glass. “For all buildings, moving plants away from windows and into the interior portions of the building helps. If plants can’t be moved, adding a curtain or room divider between the plant and windows prevents birds from trying to fly toward the plants on the inside of the building.”
In 2016, Washtenaw Safe Passage and Detroit Audubon Society began to collaborate on Safe Passage Great Lakes with the help of Erin Rowan, Detroit Audubon’s research coordinator. This was a crucial step to standardizing data collection and training protocol for volunteers in addition to sharing combined education and outreach forces. Washtenaw Safe Passage is now recruiting a volunteer coordinator to help expand monitoring and outreach.
We can protect birds including threatened species with window modifications, minimized lighting, and by advocating for Safe Passage and Lights Out programs.