How many birds are killed in the U.S. each year by window strikes?
Studies show that one billion birds are killed every single year by window strikes–in the United States alone (Kornreich, et. al. 2024). This shocking figure averages out to almost 3 million every single day. Unsurprisingly, window collisions are one of the largest anthropogenic causes of bird decline. Typically, window collisions are fatal for birds due to their small size and fragile, hollow bones. Of the birds that survive these high-speed, head-on collisions, most are seriously injured and likely to eventually succumb to their injuries. They often suffer from broken and fractured bones, internal bleeding, and severe head trauma.
Any building with windows poses a potential threat to birds–not just tall, commercial buildings. In fact, shorter buildings–one to three stories tall–account for almost half of all collisions (Loss et. al. 2014). Furthermore, the risk of collisions greatly increases if a building’s windows allure birds with the reflection of nearby vegetation. Thus, collisions in suburban and residential areas are very common.
Why do birds fly into windows? Unlike humans, birds can’t use context clues to distinguish reflections from reality. While frames, shutters, and other visual cues alert humans to the presence of a window, all birds notice is the reflection of vegetation or open skies. Secondly, birds are easily confused by artificial light at night. Oftentimes, birds spot clusters of lighted windows in urban and suburban areas and fly toward them–either crashing into them or becoming disoriented, aimlessly circling the area, and depleting their energy.
What you can do
Luckily, there are a number of things you can do to greatly reduce the likelihood of collisions. Innovative products have been developed to alert birds of the danger of reflective windows. First, it’s important to identify problematic windows. Large, reflective windows near vegetation tend to cause the most issues. Windows positioned near bird feeders can also cause issues.
Window films and decals are a popular choice for homeowners and commercial buildings alike. They give birds the visual clues they need to stay away from windows. Films and decals are inexpensive, easy to install, and there’s a wide range of options available. Some companies offer UV coated films and decals, which are visible to birds and translucent to humans. Other companies manufacture one-way glass and films so that windows are opaque from the outside and fully transparent from the inside.
Note, that patterned films and decals are only effective if properly installed. They must be placed outside of the window. If placed on the inside of a reflective window, they’re practically invisible. It’s also important to ensure that patterns are appropriately spaced. More than two inches of space between stripes or dots won’t necessarily deter smaller birds who are capable of flying through tight spaces.
Another popular choice is vertically strung cords placed outside of windows. These solutions are successful for the same reason films and decals are. They present a visible obstacle to a bird’s flight path through the window. They’re more noticeable than films and decals, so they can be placed further apart and still be effective. Most sources recommend four inches of spacing between cords.
There are also several home remedies that can be quite effective in reducing collisions. External bug nets, for example, make windows more visible and cushion crashes. Some people prefer to paint a translucent design on the outside of their windows. Others partially close their shutters or Venetian blinds. And of course, dirtier windows are much easier to see than clean, highly reflective windows. By letting your windows get dirty, you’re actually doing birds a service!
Lastly, make sure to turn your lights off at night–especially lights that are positioned near windows. If you need to keep a light on, you can also draw your blinds or close your shutters.
What to do if a bird strikes your window
If a bird strikes your window and is unable to fly away, it likely needs attention. If you’re comfortable handling the bird, pick it up place it in a dark and warm confined space. Cardboard boxes and well-ventilated cloth bags work well. The A calming environment will help the bird recover from its stress response. After handling the bird, be sure to wash your hands well. Contact the nearest animal hospital for help. You can also contact us at (907)-888-2121, and we’ll offer advice or redirect you to other resources.
Sources
Scott R. Loss, Tom Will, Sarah S. Loss, Peter P. Marra. 2014. “Bird-Building Collisions in the United States: Estimates of Annual Mortality and Species Vulnerability.” The Condor 116 (1): 8-23. https://doi.org/10.1650/CONDOR-13-090.1
Ar Kornreich, Dustin Partridge, Mason Youngblood, Kaitlyn Parkins. 2024. “Rehabilitation Outcomes of Bird-building Collision Victims in the Northeastern United States.” PLoS ONE 19 (8): e0306362. https://doi.org/10.1371/journal.pone.0306362