It was one of the biggest joys of the season when Wood Thrush arrived in northern Mississippi as they emigrated in the spring and began serenade for my neighbors with their ethereal, harmonious songs. This is also a small miracle. These tiny creatures have just flew more than 1,850 miles (3,000 kilometers) and have been running away from Central America.
Other birds take longer journeys – for example, Swanson’s thrush nests into the northern forests of Alaska and spends a non-breeding season in northern South America, traveling up to 5,600 miles (9,000 kilometers) per method.
These amazing travel feats are inspiring, which makes it even more miserable when they edit the deadly collision with the glass windows.
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This happens out of shocking regularity. Two recent scientific studies estimate that in the United States alone, each year collides with glass and sometimes gets immediate but often injured.
In fact, the collision of windows is now considered the main cause of bird death. Due to window collisions and other reasons, bird populations in North America fell by more than 29% from 1970 levels, potentially having a significant impact on the world’s ecosystems.
These collisions occur on every type of building, from houses to skyscrapers. On the University of Mississippi campus, where I teach and do research with my colleagues, I have been testing some creative solutions.
Why glass is often fatal to birds
The most common glass is a mirror that reflects a clear sky or habitat. When there seems to be a passionate tree or shrub, there is no reason for the bird to slow down.
These frontal collisions often result in brain injuries and birds often succumb immediately.
In other cases, birds were shocked by collisions and eventually flew away, but many of them ended up dying from brain swelling.
For example, other injuries to the wings or legs may make birds incapable of flying and are susceptible to cats or other predators. If you find an injured bird, please contact your local wildlife recovery person.
Which window is the most dangerous
Some windows are much worse than others, depending on how far they are from bushes and other bird habitats, what they reflect, and how indoor lighting exacerbates or reduces the mirror effect.
On our campus, some buildings with large areas of glass surfaces surprisingly killed few birds, while a small number of other windows were deadly.
A special elevated sidewalk with glass on both sides between chemical and pharmacy buildings is a well-known dangerous attraction. Glass kills migratory birds every spring and fall as they try to pass between two buildings heading to Grove, the university’s Central Campus Park area with large oak trees on it.
During the 2020 pandemic, student Emma Counce conducted a survey of 11 campus buildings every day during the spring migration. She found 72 birds dead in seven weeks. Five years later, my ornithology major completed a new survey and found 62 deaths in the five weeks of 2025, indicating that we still have a lot of work to do to make our campus safe for migratory birds.
Thrushes may be due to their tendency to tilt in narrow spaces beneath dark forests, disproportionately represented among victims. Others include colorful songbirds - Northern Palulas, Black and White Warblers, Primitive Warblers, Kentucky Warblers, Bontes, Vireos and Tanagers.
How to reduce hazards in windows
The good thing is that everyone can do something that reduces the risk.
Film, stickers or strings can be added to the outside of the window to form dots or lines 2 to 4 inches apart, destroying the reflection and thus creating the appearance of the barrier.
The exterior screen and shutters are also good. By the way, adding just some Predator profile stickers is ineffective - treatments need to span the entire window.
When applied correctly, window processing can make a huge difference. An inspiring example is the McCormick Place, Chicago, the country’s largest convention center, which killed nearly 1,000 birds on one night in 2023. In the area where workers applied Dot film to the building's windows equivalent to two football fields, the bird mortality rate in the lakeside building has been reduced by 95%.
The Bird Collision Prevention Alliance provides information on the choice of remodeling a home or office window to make it more friendly.
Options for new windows are also becoming more common. For example, the New Science and Technology Innovation Center on my campus has many windows, most of which are bird-friendly glass with subtle dots on it. This spring, we found that despite the high surface area of the glass, it killed only four birds.
How do you help
When trying to change your home, I recommend starting from a young age. Note which specific windows have killed the birds in the past and treat them first.
Use it as an opportunity to understand which method is best for you and your building. Either order the product or make the product yourself and install it.
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Then make another one and tell your friends. In the office, talk to people, find other people who care and build teams to change step by step.
With some creative solutions, anyone can at least reduce this major risk.