- Overview
- Light Pollution
- Collisions
- Collisions Research
- Policy
- Architecture
- Enthusiasts
The National Park Service's Night Sky Risk Map, zoomed in closer, highlights Morgan Hill State Forest near Syracuse, NY, and Eagle Rock Reservation near New York City, showcasing the stark contrast between relatively dark areas and regions heavily impacted by light pollution.
To better understand the visual impact of light pollution, this side-by-side comparison, with both images exposed the same (f/5.6), reveals its profound effect on the night sky. On the left, the clear, star-filled sky over Morgan Hill State Forest in Onondaga, NY—just 25 miles from Syracuse—contrasts sharply with the right image from Eagle Rock Reservation in Essex County, NJ, only 15 miles from New York City. Here, urban light, known as "skyglow," obscures nearly all stars. This intense light pollution not only limits our view of the stars but also disrupts migratory birds, which rely on natural darkness to navigate. The artificial glow can lead to disorientation, often resulting in fatal collisions with buildings.
Texas Conservation Alliance member and Assistant Coordinator of Lights Out Dallas!, Heather Bullock (left), leads a team of volunteers during a 6 a.m. collision monitoring walk. From March 1 to June 9, 2024, the spring migration season, an estimated 1,312,174,000 birds have migrated through Texas. “We know that light pollution is extremely disruptive to birds who primarily migrate at night and use the stars to navigate,” says Bullock. “Light pollution causes them to not see those stars—they lose their map. So they come down lower to try to find their way by physiography. And when they do, they’re in great danger of colliding with human-made structures.”
The dark glass facade of a Dallas skyscraper rises into the night, illuminated only by a faint line of lights at the top. By using minimal lighting, the building helps reduce risks for migratory birds, though its reflective glass can still pose challenges. Early morning reflections, when interior lights are switched on, can confuse birds, who may mistake them for open sky or vegetation. “Dallas ranked as the third worst of 125 large cities for exposing birds to light pollution,” recalls Tim Brys, a founding volunteer. To address this, the Lights Out Dallas! campaign—part of the statewide Lights Out Texas! initiative—encourages reducing non-essential lighting across the DFW metroplex. In response to the Texas Conservation Alliance’s call for bird-friendly practices, Dallas continues to make strides, with Reunion Tower and The Hunt Building officially participating in Lights Out this spring. “Aiming to ensure a darker night sky, all business owners and residents are encouraged to go lights out during bird migration seasons,” explains the Texas Conservation Alliance.
Older buildings, such as this one, often pose less risk to birds due to their less-reflective design; however, all structures play a role in urban bird safety. To better understand bird building interactions, collision monitoring has become a crucial component of the Lights Out Texas campaign. While the campaign’s primary focus is to reduce light pollution during peak migration seasons to prevent bird disorientation, collision monitoring provides essential data that highlights the need for these protective measures.
A deceased Song Sparrow (Melospiza melodia) lies beneath the Kay Bailey Hutchison Convention Center skywalk, one of many casualties recorded along the collision monitoring route. Collision monitoring involves early morning walks by volunteers, especially during peak migration seasons that occur each spring and fall, to identify and document birds that have struck buildings overnight, providing valuable data on how urban structures impact migratory species. Initially, Brys and Ben Jones from the Dallas Zoo mapped out hotspots across downtown, gradually adding buildings to the survey based on observations and expert insights. Today, the collision monitoring teams cover a 7-mile route spanning 23 buildings, gathering data to advocate for bird-friendly urban design and reduce these preventable collisions.
Heather Bullock and Lights Out Dallas! intern Brendon Williams walk their portion of the collision monitoring route, checking behind barricades and shrubs and pausing at large windows where bird strikes are common. Although they initially find no casualties, they approach the Kay Bailey Hutchison Convention Center—a known hotspot. "The Convention Center is the worst collision source in downtown Dallas. Over a quarter of all collisions we’ve recorded since the start of Lights Out Dallas! have happened here," Bullock explains. Soon after, they find a deceased Lincoln's Sparrow (Melospiza lincolnii) near a large meeting room window. They document the scene, label the bag “Convention Center Stairway,” and store the bird for data collection. “The Convention Center is being renovated, and Texas Conservation Alliance has reached out to the architects involved,” Bullock adds, noting this as a prime opportunity to install bird-friendly designs. So far, there has been no progress.
The Skywalk, or “Skybridge,” connects the Kay Bailey Hutchison Convention Center to the Omni Dallas Hotel. Built in 2011, the Omni’s untreated glass poses a serious threat to migratory birds. Dallas is not alone in facing this issue; Chicago’s McCormick Place Convention Center has become notorious for large-scale bird collisions, with nearly 1,000 birds striking the building in a single night during the fall of 2023. A study published in the peer-reviewed journal Proceedings of the National Academy of Sciences (PNAS) on McCormick Place found that "reducing lighted window areas could lower bird mortality by about 60%." Since October 2023, McCormick Place has begun lowering window shades nightly, following recommendations from the U.S. Fish and Wildlife Service. New York’s Javits Convention Center saw similar success, achieving a "90% collision reduction after implementing bird-friendly measures in 2013," according to the National Audubon Society.
Bullock stands beside the back of the convention center skywalk, wearing a volunteer leader vest and pin. Though not entirely made of glass, this part of the structure still poses a significant hazard for birds. According to the National Audubon Society, “internal plants near windows, glass corners, and greenery close to buildings can all be deadly as birds are unable to distinguish reflection from open flyway.”
After the survey route is completed, volunteers gather around Tim Brys’s truck, preparing to document the morning’s findings for Lights Out Dallas! Brys distributes clipboards, specimen tags, and the bird log binder, instructing volunteers to record details like species, location, and casualty ID. Each entry is logged both physically and in an online database, iNaturalist, where the data remains accessible to researchers and the public. Occasionally, the team finds birds that can still manage to be saved, "Stunned and injured birds get taken to Rogers Wildlife Rehabilitation Center for 'repairs' and hopefully are hopefully re-released," says Brys.
Brys holds the collection of birds documented on April 22, 2024. “We wanted this information to stay open source, where it was transparent,” says Brys. “There’s actually a number of people that pull data from that information, including the city of Dallas.” The iNaturalist entries help researchers map collision sites, offering valuable insights into patterns and hotspots across the city.
Tim Brys stands in front of a freezer in the Perot Museum’s teaching collection, where the deceased birds are temporarily stored. "All the deceased birds get frozen individually with their respective data tag that matches their iNaturalist entry," Brys states adding, "Birds get saved until either someone is traveling to College Station or until a full freezer creates need for an extra trip down. Drop-offs are all loaded into a giant cooler filled with bags of ice for the drive down."
Since taking on a leading role with Lights Out Dallas!, the Texas Conservation Alliance has expanded its mission beyond collision monitoring to include education and community engagement. "We’re working with teachers to develop a Lights Out Texas! curriculum for 7th and 8th grade, though it’s still in progress," explains Mei Ling Liu, Texas Conservation Alliance's Community Conservation Director. "An Austin team from Defenders of Wildlife and Travis Audubon has created a curriculum for 3rd to 5th grade, currently in testing. In the future, we hope to encourage older students to advocate for change by reaching out to city officials, writing letters to mayors or councils, and promoting Lights Out initiatives in their communities."
When asked about the growing impact of Lights Out Texas!, Tim Brys shares how the initiative is expanding beyond Dallas: “We had someone reach out who used to work with us on the project here in Dallas. She’s now in Austin with Defenders of Wildlife and asked for help. It’s kind of spreading out.” Bullock emphasizes that collaboration among scientists, citizen scientists, and community enthusiasts forms the backbone of the program. “We know what the problem is. We know what the solution is,” she says. “The biggest thing is just raising awareness. Our role is to spread the word, inviting people to stand with us to protect these birds that are essential to our ecosystem.”
Heather Prestridge organizes preserved Common Yellowthroats (Geothlypis trichas) in a drawer in one of the many cabinets that store specimens collected throughout the years at the lab. Dallas isn't the only location that the lab collects collision monitoring samples from. "Houston, Austin, San Antonio, Galveston, Fort Worth. They spend a little bit of time in our freezer, and we rely on a volunteer crew of students to prepare the specimens to our museum standards," says Prestridge.
Prestridge opens another drawer, revealing a variety of bird specimens, each of which migrates through Texas. "The gold standard for museum specimens is to retain all diagnostic characteristics," she explains. "Birds are identified by plumage, which is why we preserve the skin. Our specimens hold significant value because we can record mass, measurements, reproductive condition, age, and body condition. All of these data points are cataloged in our database, linked to each specimen, enhancing their scientific utility."
Prestridge's hand reaches toward the pinned bird specimens arranged on a foam board, each tagged and meticulously organized for study. The yellow pins hold the birds in place, allowing researchers to examine features like plumage, body condition, and other physical characteristics as part of ongoing research. "We take the skeleton and all of the insides out of the bird, so you're left with just the skin," Prestridge explains. "The skin is filled with cotton and then carefully sewn shut, so it’s still a floppy piece of empty bird. Pinning them onto the board allows them to dry in a really neat fashion... they'll be sturdy for a long time. Once it's dry, you can't go back and change it."
A close-up of labeled bird wing specimens, carefully tied and stored for study. "Spread wings are important too, because you can't spread the wing of a prepared bird specimen," says Prestridge. The preserved wings, tagged with identification numbers, allow researchers to examine molt patterns, age, and other morphological details without needing a full specimen. "When we get, say, 109 white-throated sparrows from Dallas in a season, we sort through them and decide to turn some into spread-wing specimens. The spread wings are quicker to prepare. They also serve as good training for newcomers to specimen preparation, helping them understand how delicate the process is."
A frozen storage unit houses rows of meticulously organized drawers filled with preserved bird samples, each carefully labeled and cataloged. These samples, collected as part of Texas A&M’s biodiversity efforts, are invaluable for both research and collaboration. "We've spent a lot of time collaborating with other colleagues here at Texas A&M but also UT San Antonio, and a couple other universities," says Heather Prestridge. "The Lights Out! birds... provide a large sample size in a small amount of time." These specimens have allowed researchers to explore a variety of pressing issues, from avian influenza and avian Borna virus to the presence of microplastics in bird populations. "We here at our collections save a tissue sample, typically a piece of heart and a piece of breast tissue... data are shared for those alongside the specimens, for anyone who wants to use the data or wants to request tissue samples," she adds, emphasizing the usability of the samples. "We believe our collections will endure indefinitely, as our primary focus is documenting biodiversity across space and time," Prestridge concludes. The specimens provide valuable insights into ecological changes of the past, present, and future.
The Powdermill Avian Research Center’s flight tunnel, developed with the American Bird Conservancy, allows researchers to study bird behavior around various window treatments. Birds from the center's banding program briefly participate in controlled flights toward two panes with different materials, helping assess bird-safe glass options. "American Bird Conservancy, and Dr. Christine Shepherd," Anikó Tótha explains, "adopted the glass testing tunnel over 10 years ago. Our two tunnels are based on the first built in Hogan, Austria, which tests transmission. [These] are the two tunnels we have now, one at Powder Mill and the second at Forman Branch Bird Observatory affiliated with Washington College."
A bird safely makes contact with a net inside the flight tunnel at Powdermill Avian Research Center. This controlled setup allows researchers to test and identify effective bird-safe glass solutions to help reduce collisions in real-world environments.
Dan Piselli, Director of Sustainability at FXCollaborative Architects, points to bird-friendly decals applied to his office building's glass façade. These decals were added after observing bird collisions during migration seasons near the 7th-floor terrace, which faces neighboring green roofs. The retrofit uses a proven collision-mitigation product that balances bird safety with maintaining clear views and daylight.
Piselli evaluates bird-friendly decals similar to the ones installed on the façade. "It’s clear that human impact on Earth is devastating the ability of life to continue," he stated in an email. "Bird-friendly glazing is a rare example of a material with a very direct effect, literally saving the lives of birds every day," Piselli emphasized, illustrating the immediate impact of sustainable design choices.
A close-up view of bird-friendly glazing, often implemented into building designs by architects at FXCollaborative, highlights the intricate patterns designed to prevent collisions. "There are a number of available technologies to mitigate bird collisions with glass in new buildings," Dan Piselli explains. "Each can be applied to make patterns on the glass that birds can see. Technologies include ceramic frit, which is baked onto the surface of glass, etching achieved with lasers or acid application, and UV-reflective coatings."
Rising along Brooklyn's Greenpoint waterfront, 1 Java Street is a new construction project designed with bird-friendly Guardian Glass to help prevent bird collisions. This building is part of New York City's commitment to environmentally conscious construction through Local Law 15. The installed glass is UV-treated, similar to the glass being tested at Powdermill, and is intended to deter birds.
A close-up of the bird-friendly glass materials used at 1 Java Street. Here, the UV patterns are faintly visible due to the angle of reflection at sunset, which enhances the visibility of the UV-reactive materials.
Bird-friendly design solutions often extend beyond their primary purpose. At the Columbia School of Nursing, translucent frit patterns are applied to private room windows, which not only mitigate bird collisions but also enhance privacy, reduce glare on the street, and decrease solar heat gain to lower air conditioning loads. "The frit was primarily used to provide privacy for students and faculty, as well as for residential apartments across the street. In addition, the frit helps mitigate bird collisions, reduce glare onto the street, and reduce solar heat gain to reduce air conditioning loads," Dan Piselli explained.
Eliza Wein, a senior at Cornell University studying Environment and Sustainability, sits quietly outside the Cornell Lab of Ornithology. For Wein and many like her, appreciation for birds is more than a hobby—it’s the first step toward environmental action. A dedicated member of "Birding Club Cornell," Wein has worked hard to protect birds on campus. “There’s a group of students on the Cornell campus... called Cornell Dead Bird Alert,” she explains. “When there’s a dead bird on campus that’s collided with a window, we report it to that group. I think we’re probably the only college that does that.” “People love what they know,” she reflects. “If you get someone to love birds, you’re making a conservationist right there.”
The best way to appreciate birds has traditionally been with binoculars. Depicted here is a "spotting scope." While binoculars offer a wider view, a spotting scope provides higher magnification. Modern technology is introducing new ways to enjoy birding. Apps like Merlin, developed by the Cornell Lab of Ornithology, help identify birds by sight and sound, making birding accessible to those who might not have considered it before. “My friend, who’s a computer science major, didn’t care about birds before, but now he’s really into birding—largely because of Merlin. Apps like Merlin bring birding to the masses, making it accessible to people who wouldn’t otherwise care about birds,” says Eliza Wein.
Leo Gilman, an Environment and Sustainability major with a Humanities Concentration at Cornell University, stands on the roadside using the Merlin Bird ID app to identify birds by their calls and movements. "Phones are so useful for birding, so I use mine a lot," Gilman explains. “Merlin is incredible—it makes birding accessible to anyone. You can identify birds by sound, by sight, or even from a photo. It’s just so convenient.” As a Student Worker Level II at Birds of the World, Gilman has worked on copyediting and managing tables, photos, and maps for the publication. He emphasizes how technology has revolutionized birding. “I rarely take a camera with me, because so often I focus more on the photo than watching what’s in front of me. Apps like Merlin let you engage with the birds in real-time without needing expensive equipment.” For Gilman, birding is about connection. “You just need to be out there, looking at or hearing birds in whatever way you want. Merlin makes that so much easier for everyone.”
This wetland in High Island, Texas, covered in green vegetation and surrounded by bald cypress trees, serves as a critical stopover point for migratory birds flying over the Gulf of Mexico. It provides food, shelter, and rest along their journey. Conservation efforts by birding enthusiasts and environmentalists help keep these habitats as safe havens for birds during their seasonal migrations.
Members of Cornell's Golden Wing Society gather in High Island, Texas, for a week-long birding trip with Victor Emanuel Nature Tours. Among them is Sally Alhadeff, a dedicated bird watcher since the 1970s, who reflects, “Birds are more than just background noise—they add a richness to our world that we can't replace. Protecting them is crucial.”