Invisible Threats
Stop Bird Collisions—One Window at a Time
Millions of birds die each year in North America after flying into windows they can’t see. Reflections and clear glass confuse birds, especially during migration, leading to fatal strikes. But with simple solutions—like adding decals or dot patterns to glass, turning off lights at night, and placing feeders closer to windows—you can help prevent these collisions. Whether at home or in the city, every treated window makes a difference in protecting native bird populations.
How Windows Harm Wildlife
Every year, hundreds of millions of birds die in North America after colliding with windows. To us, windows are just part of everyday architecture. But to birds, they can be invisible and deadly. As cities expand and buildings multiply, this largely preventable threat has become one of the top human-caused killers of birds—especially during spring and fall migrations.
But the good news is: there are simple, effective ways to stop these tragedies. Whether you live in a high-rise or a house, your windows can be part of the solution.
Why Birds Hit Windows
Birds don’t understand glass. They see reflections of sky, trees, or open space—and fly toward what looks like a safe passage. At night, lighted windows can attract and disorient migrating birds, especially in poor weather. During the day, large or clear panes of glass may appear invisible altogether, leading to high-speed impacts.
Bird-window collisions can happen anywhere: suburban homes, office buildings, high-rises, or even garden sheds with glass doors. All it takes is the right lighting, a reflection, or a transparent corridor between windows on opposite sides of a building.
Why It Matters
The Scale Is Enormous: Scientists estimate that up to one billion birds die each year in North America from window strikes.
It Affects All Kinds of Birds: While some urban species like pigeons and house sparrows are more visible, most window strikes involve native songbirds like warblers, thrushes, finches, and hummingbirds—many of which are already in decline.
It’s Preventable: Unlike habitat loss or climate change, window strikes are a direct threat we can easily reduce—right now.
How You Can Prevent Window Collisions
Luckily, protecting birds from windows doesn’t require major renovations or expensive tools. Here are proven strategies you can use at home, school, or work:
1. Make the Glass Visible
Birds need to recognize glass as a barrier. That means creating a visual pattern birds can’t ignore:
Use decals or stickers: Place bird-safe window decals, dots, or patterns on the outside of the glass, spaced no more than 2 inches apart horizontally and 4 inches vertically. These break up reflections and make windows more visible.
DIY dot patterns: Apply tempera paint, soap, or masking tape in dot or stripe patterns. You can even use a ruler and a paint pen for a clean, semi-permanent look.
Commercial films: Use special films or screens that go over the exterior of the window and create a visible barrier while preserving your view from inside.
2. Close Curtains or Blinds
Closing curtains during the day, especially on windows with clear views through the house, can reduce transparency and prevent birds from seeing a "flight path."
3. Move Feeders and Plants
Ironically, bird feeders and birdbaths placed close to windows can lead to more strikes—but the solution isn’t removing them:
Place feeders within 3 feet of windows. At this distance, birds can’t build up enough speed to be seriously injured if they do hit the glass.
Avoid placing feeders 10–30 feet away from windows, where high-speed collisions are more likely.
4. Turn Off Lights at Night
Lights at night confuse migrating birds, especially those flying long distances in spring and fall. This light pollution causes them to circle buildings and increases the risk of collisions.
Turn off unnecessary indoor and outdoor lights between 11 p.m. and dawn, especially during peak migration seasons.
Use motion sensors or downward-facing lights for outdoor lighting to reduce constant glare.
5. Advocate for Bird-Friendly Design
Support local ordinances that require bird-safe building practices, especially for new construction.
Encourage schools, businesses, and institutions to install bird-safe window treatments and reduce lighting during migration.
Every Window Counts
You don’t need to change your whole house to make a difference. Treating even one or two large or reflective windows can save countless lives over the years. And when entire neighborhoods or cities join in, the results are profound.
Think of your windows not just as something to look through—but something birds might see into. With a few thoughtful changes, you can make your home part of a growing movement to protect wildlife and preserve the sound of birdsong in our lives.