Saving Birds by Reducing Window Strikes

By Colleen O’Hara

Birds are beautiful and fun to watch. Did you know they are also beneficial? A lot of bird species spread plant seeds and pollinate plants. They are also predator and prey, and good indicators of how well an ecosystem is doing.

The overall bird population in North America is in decline, based on research reported in the journal Science. The study reports a 2.9 billion net population decrease over the past 50 years due to factors such as loss of habitat and the impact of human activities.

Window strikes are one human activity threat to birds that we can do something about now. Between 600 million to 1 billion birds die in the United States every year from hitting windows, almost half of this number in homes.

Windows are tricky for birds because glass often reflects the surrounding environment, including trees or sky, or appears transparent, and birds are unaware there is a barrier there. In addition, lighting—inside and outside a building—can confuse birds, especially at night, making collisions more likely. Many collisions also occur when birds are at a backyard feeder and get startled.

You might assume skyscrapers pose the biggest threat to birds but less than 1 percent occur at buildings over 12 stories, according to the American Bird Conservancy. Homes and other buildings, one to three stories tall, account for 44 percent of window strikes where birds are most active. Most victims are songbirds migrating during the fall and spring.

Taking small steps at your own home can have a big impact in reducing window strikes. Here are some suggestions that are particularly beneficial for larger windows:

1. Use tape, string, dot patterned designs, paint, or decals on the outside of the window no more than 2 inches apart and covering most of the glass. Any wider, and birds will think they can fly through the gap. Remember to place these on the outside, not inside, of the window to be effective. Also, any product added to a window should be seen from at least 10 feet away, so birds have time to react while in flight. And products with ultra-violet patterns aren’t as effective in low lighting and can’t be seen by raptors and pigeons.

(Here is more product information from the American Bird Conservancy that rates products/solutions on their effectiveness.)

3. Use external insect screens to eliminate reflections and offer a cushion if birds do hit.
4. Turn off unnecessary lights at night. Consider putting outside lights on a sensor and turning off inside lights when possible or draw the curtains. Especially during nocturnal migration, outdoor lights can disorient birds in flight.

Sadly, most birds die from window strikes, even if they appear ok and fly away after a collision. The best chance for a recovery is to take a bird to a wildlife rehabilitator, according to Cornell Lab. If possible, capture the bird and put it in a cardboard box lined with a paper towel and place it in a quiet location. Do not give it food or water and call a rehabber in your area. Cornell provides an online directory of rehabbers, including the Virginia Department of Wildlife Resources, which lists permitted wildlife rehabilitators by location.

There are still many unknowns about bird window strikes, such as when and where they are most likely to occur, according to John Swaddle at William & Mary University’s Institute for Integrative Conservation. Do they happen in the morning or middle of the day? What part of the window is the most likely to be hit? Are more birds dying from window strikes than we realize because some of them fly away?

To help answer these questions, the Institute is developing a window sensor, Swaddle said during a Webinar sponsored by Virginia Master Naturalists. The Institute is also watching how birds interact with—and even avoid—windows in a lab environment (ensuring that no birds collide with the window but hit a safety net first). Also in the works is a mobile app that will allow homeowners to determine their risk score for window bird strikes and offer possible solutions.

Being proactive and following any of the suggestions above can be a great help in protecting birds, Swaddle said. “Any action is a positive action when it comes to bird window collisions.”

Photo 1: The White Throated Sparrow is one of the most common victims of window strikes. Photo by: Joshua J. Cotten on Unsplash.