Window strikes are the second most common cause of death for wild birds. This is estimated to cause between 100 million to 1 billion bird deaths in the US annually. Even when a bird appears to be temporarily stunned from a window strike before flying away, it may die later on from internal bleeding, bruising, and/or brain trauma.
Window strikes are especially common during spring and fall. Birds travel much more during migration seasons, so the odds of striking a building increase. Daytime window strikes occur because birds see the reflections, not the windows. Oftentimes, birds are attracted to the trees and plants they see in the reflections. Occasionally, a bird sees its own reflection and attacks it. Window strikes are also a problem at night, especially in foggy weather. Nocturnal migrating birds use the stars to navigate, but the lights inside homes can steer birds off course.
The good news is that there are some easy steps to prevent birds from striking windows. The easiest way to prevent nighttime strikes is to turn the light off when you leave a room. The same goes for offices after business hours. One study found that turning the lights off in just one building reduced window strike deaths at that location by 83 percent.
You can also mark windows to prevent window strikes. One option is one-way transparent film. This will allow you to see outside while making the window more visible to birds.
Another popular option is window decals. In order for this to be effective, you’ll need to cover the majority of the windows with decals on the exterior, placed less than four inches apart. If you are deterring hummingbirds from window strikes, place the decals less than two inches apart. It was once believed that bird of prey decals would scare away birds, but this has been found to be false. Therefore, bird decals aren’t the only way you mark your windows to make them visible. Strips of tape (placed the same as decals) are also suitable.
Some people use tempera paint, soap, or markers on windows. You can make a 4-inch x 4-inch grid or make your own patterns; just make sure the majority of the window is covered. Ultraviolet markers are not ideal because the ink fades within a few days.
At home, it is helpful to have screens on the outside of windows. If this is not possible, you can cover the window with small-mesh netting or mosquito screens. Mount the netting from a frame at least three inches from the glass. It needs to be taut so that birds will bounce off it. You can find netting at garden stores, though it may be sold as netting for trees and shrubs.
If you are renovating your house, choose double-hung windows. Dividers are helpful for large picture windows. You can also install external shutters or sun shades. Should you have interior vertical blinds, it is helpful to keep the blinds half open.
If you find a bird that has struck a window, make sure its wings are held properly and not dangling, and check its eyes. If there are no injuries, let it recover on its own. It may just be stunned and need time to regain its senses.
If you do observe injuries, you need to transport the bird to a wildlife rehabilitator as soon as possible. Call your local wildlife rehabilitator to ensure that they can care for an injured bird. Wear disposable gloves to put the bird in a dark, ventilated box (you do not need to worry about the bird smelling like humans, but gloves will keep you from coming into contact with open wounds, blood or illnesses).
If you cannot transport the bird immediately, leave the box in a quiet space outdoors safe from predators. Do not try to give the bird food or water because birds are very susceptible to aspiration pneumonia. Check on the bird every 15 minutes. Unless the bird has a serious injury, it should revive within several minutes. In the event of inclement weather, you can take the covered box inside. However, do not open the box indoors, handle the bird, or keep it too warm. Keep the box away from indoor pets. Take it outside every 15 minutes to check on it. If the bird does not revive within a few hours, take it to a wildlife rehabilitator immediately.