NORMAN — Earlier this month, 395 migrating songbirds died in a single night after colliding with a glass-sided tower in Galveston, Texas.
Shortly thereafter, the building shut down its nighttime floodlights to help prevent future deaths, but fatal interactions between birds and glass buildings have become a major concern in many cities.
Most bird deaths occur between ground level to 40 feet which the American Bird Conservancy calls the primary bird collision zone.
Between 350 million and 1 billion birds die annually as a result of building strikes in the U.S. with about 56 percent of those at low-rises, 44 percent at residences and less than 1 percent at high-rises, according to a 2014 study by Scott R. Loss, Tom Will, Sara S. Loss and Peter P. Marra (“Bird–building collisions in the United States: Estimates of annual mortality and species vulnerability,” bioone.org).
Awareness is the first step toward a solution, according to avid birder and Norman resident Nathan Kuhnert.
“Here in Norman, we don’t really have what I call a large concentration of high glass buildings close to a migrant track, but, at the same time, these new glass buildings are going up in a hurry,” he said “We are in a zone that can catch both eastern and western migrants. We’re only a night’s flight away from the Gulf of Mexico, so a lot of birds do fly over central Oklahoma all of the way from the boreal forest in Canada down to Central and South America. Some of these birds have that long of a migration.”
Cities like San Jose, California, San Francisco and New York City have worked with the Aububon Society and the American Bird Conservency to create bird-safe building standards.
The bird-safe standards are often voluntary, but the dialogue is important in bringing the issue to the public’s awareness, Kuhnert said.
As Norman continues to grow and develop, the city has a chance to be proactive and turn a global problem into an opportunity, he believes. While he hasn’t monitored Norman for bird fatalities based on window collisions, Kuhnert has been tracking and documenting bird deaths in downtown Oklahoma City for a decade.
“I went to work downtown in Oklahoma City in 2006, and I started seeing signs of this problem, especially in the spring and fall,” Kuhnert said. “It struck an emotional chord in me. The more I learned about these occurrences, the more I wanted to study them. It became personal.”
• Preventing fatalities: Lights and landscaping can exacerbate the high risk of bird deaths.
“Most of these occurances can be prevented,” Kuhnert said. “Not all glass is created equal. Some glass already has properties in it that may not be conducive to bird strikes.”
Using guidelines from the American Bird Conservancy, San Jose adopted its voluntary bird-safe building standards in 2014 as a proactive measure.
“What I like about it is it identifies that there is a global problem with bird window collisions, and it provides good high order information on how to start addressing the problem,” he said.
The American Bird Conservancy identifies glass collisions as “the single biggest known killer of birds in the United States, claiming hundreds of millions or more lives each year. Unlike some sources of mortality that predominantly kill weaker individuals, there is no distinction among victims of glass. Because glass is equally dangerous for strong, healthy, breeding adults, it can have a particularly serious impact on populations.”
Advances in technology allowing for glass walls in construction has greatly increased the number of glass buildings.
“The general rule of thumb is, the greater amount of glass, the higher the incident rates and especially where there are large tracts of glass,” Kuhnert said.
The American Bird Conservancy identifies reflection, transparency and the passage effect as key factors in collisions.
Reflection is dangerous when glass buildings reflect the sky or nearby habitat, causing birds to fly into the reflection.
Birds strike transparent windows when they see interior landscaping such as plants or water features which lure them toward what looks like a friendly habitat. Skywalks and glass walls surrounding an atrium with vegetative landscaping are also danger points.
In nature, birds fly through the small spaces between leaves and branches. In some lighting, glass can appear black, creating an illusion of a passageway.
“Generally speaking, birds migrate at night, and when you have a lot of light pollution it attracts birds and might bring them down,” Kuhnert said. “Some of them are crashing in the middle of the night, but research has shown that many of them die the next day (when they take off). Bird window collisions can happen any time during the day.”
• Local fatalities: Kuhnert has monitored bird deaths during early morning hours in the OKC downtown business district, where there are several tall, glass-faced buildings. The lush vegetation at Myriad Gardens and large buildings just north of it, create a hazard, he believes.
“As OKC continues to beautify and bring in additional landscaping, with untreated glass you’re making it more dangerous for birds,” he said. “It’s all about context, not just the amount of glass.
“I’ve documented in a fairly systematic manner a large number of strike victims and, based on conversations I’ve had with folks who clean up the sidewalks around these buildings from the security crew to landscaping, just in that approximate quarter mile grid north of the Myriad Gardens, I believe there are about 1,000 migratory birds that are window strike victims annually.”
There are solutions. Glass with etched designs take away from the reflection and the transparency. Fritting (ceramic dots) has been used to reduce heat and break up light, resulting in a building that is more energy efficient but that may also be safer for birds, according to the American Bird Conservancy.
In other cases, it’s not clear why a building isn’t posing a hazard.
“I haven’t found any evidence of window strike victims at the downtown OKC library,” Kuhnert said. “I don’t know if it’s because of the property of the glass or how the building is oriented or the landscaping, but there’s something — it’s not having a high incidence of window strikes.”
Did you know?
The American Bird Conservancy identifies glass collisions as “the single biggest known killer of birds in the United States."
Between 350 million and 1 billion birds die annually as a result of building strikes in the U.S. with about 56 percent of those at low-rises, 44 percent at residences and less than 1 percent at high-rises, according to a 2014 study.