The Ridges Sanctuary

Preservation, Education, and Research

Nature Notes: Protect Birds from Window Collisions

Posted on Jun 10, 2024 by Jackie Rath   No Comments Yet | Posted in Blog · Nature Notes

By Dan Scheiman, Visitor Engagement Specialist

Translucent Tape Strips on Ridges Nature Center Exhibit Windows

During this past spring migration upwards of 3.5 billion birds were winging their way northwards (and even more will be flying in the fall when young-of-the-year are added). Migration is a hazardous time for birds, exposing them to all sorts of direct dangers such as predators, pollution, and bad weather. The greatest threat to actively migrating birds, however, is collisions with buildings. An estimated 1 billion birds die every year from flying into buildings, especially the windows.

There are two factors at work. One is the reflection in glass that makes birds believe it’s a corridor they can fly through. This is of course an issue during daylight hours and year-round. The other is lights at night. Many groups of birds, including songbirds, migrate at night. They navigate in part by the stars and moon, so bright city lights attract and disorient them like moths to a flame. Once close to buildings they are at risk of collision or other threats like cat predation.

While a convention center in Chicago and a stadium in Minneapolis made headlines for mass mortality events, big city buildings are not the only culprits. A study by the Smithsonian Migratory Bird Center estimated that 44% of birds killed at buildings occurred at residential structures. This means YOU have an opportunity to help birds. Even if only a few birds hit your windows each year, multiply that by all the residential windows out there and you can see how it adds up. It’s a big problem but with simple solutions.

Reduce light pollution. Turn off non-essential lights at night, especially during migration. Use motion sensors and timers. Point outdoor lights downward and install shielded fixtures. Choose bulbs with lower lumens, i.e. less brightness. Close window shades at night.

Nature Store Anti Collision Products

Create a visual barrier that birds won’t try to fly through. For new construction, the best solution is bird-safe glass, which has an etched pattern or UV-reflecting film built into it. Many bird species see ultraviolet light, so UV-reflecting film shines for them but is practically invisible to us. For existing windows, decals, strings, films, and more can be applied to the outside.

There are many products to choose from. At The Ridges we have applied translucent tape strips to our exhibit space windows, and we sell UV-reflecting decals and liquid at our nature store. Whatever you choose, the spacing between elements should be no bigger than 2×2 inches apart. Research by the American Bird Conservancy has shown that birds will fly through larger gaps.

Even if you can retrofit only a portion of your lights and glass, doing something is better than doing nothing so that one more songbird will live to see another sunrise.


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