Birds hit windows because they cannot perceive clear or reflective glass as a solid barrier. Every bird species can get confused, even birds like the Tufted Titmouse.
It's a sad experience almost all of us have had. You're sitting at home, and you hear something hit one of your plate-glass windows. You investigate and find a bird crumpled beneath the window. Many times, the bird is just stunned, and after a few minutes, it flies away. Sadly, the window collisions are often fatal. As luck would have it, the bird in question is often a less-common species, making the incident even more exasperating.
Because most of us find only one or a few wild birds a year beneath our windows, bird strikes seem like a fairly limited problem. Unfortunately, when you consider the number of homes and windows involved, bird collisions with windows is a big source of mortality for both migratory and resident birds. The good news is that it is also one of the easiest problems for homeowners to correct.
Recent studies suggest that as many as 100 million to 1 billion birds are killed in collisions with windows in the United States each year. This estimate assumes that one to 10 birds are killed at each building in the U.S., a figure that has been confirmed through more detailed studies. Unfortunately, experts believe these numbers may be underestimated because most fatalities are not noticed because the casualties are often hidden by vegetation or removed by scavengers. More than 225 species of birds have been documented colliding with glass.
Studies have found that about one out of every two window strikes results in a fatality. Although strikes occur at windows of various sizes, shapes, heights and orientations, more collisions occur with larger windows and those low to the ground. Collisions can occur during any weather condition, at any time of day and during every season. Many strikes occur during winter (when birds are attracted to feeders in larger numbers) and during migration (when large numbers of birds pass through yards and neighborhoods).
Birds hit windows because they cannot perceive clear or reflective glass as a solid barrier. Birds see trees and other habitat reflected in the window, or they see potted plants or other structures on the inside of the house. It's easy to understand how birds make this mistake. Take a walk around your home, and notice how clearly trees and the rest of your yard are reflected by windows, especially the large ones.
The Silhouette Solution
Despite the hazard to birds presented by windows, the good news is that it is a problem anyone can help reduce or eliminate. The solution is simple: Once you have identified the "killer windows," erect barriers that keep birds from hitting the glass, or do something that will help birds realize that the glass is a solid barrier. The challenge is making these simple solutions easy and aesthetically appealing to people!
The most common preventive measure is putting a raptor silhouette made of paper on the inside window surface. Contrary to popular belief, what keeps the birds from hitting the window is not fear of the raptor. Rather, the paper silhouette alerts the birds to the presence of the window.
Therefore, almost any object applied to the window will help deter birds. The most effective approach is to apply inch-wide vertical stripes of tape or other material spaced every 4 inches. This will virtually eliminate collisions but doesn't do much for your view or the appearance of the window. Many wild bird retail stores sell spider web appliques and other silhouettes that can be helpful.
Get the kids involved — they will love the idea of having their art displayed on the glass! Remember: The silhouette doesn't have to be of a bird. All we are trying to do is alert the bird that there is a window present.
The most effective approach is to apply inch-wide vertical stripes of tape or other material spaced every 4 inches. This will virtually eliminate collisions but doesn't do much for your view or the appearance of the window.
With a little creativity, window silhouettes can be quite attractive and a good way to raise awareness about the issue of bird collisions with windows. I recently saw an office building that had a long row of large, reflective glass windows at ground level. The reflective image in the windows was so lifelike, I was sure that many birds had perished there. The owners had placed about a dozen paper raptor silhouettes on the windows, creating a pleasing pattern that simulated a flock of migrating hawks. I'm sure their efforts dramatically reduced collisions and stimulated lots of questions from passersby.
Although it may take time to become used to the silhouettes on the window, I think you will find that after a while you won't even notice them. I have become so used to silhouettes on our windows that I certainly don't.
Other Ways To Help Birds
A second approach is to place something in front of the window that will prevent collisions. For example, netting can be stretched in front of the glass. Many hardware stores sell netting used to keep birds from fruit trees; this works quite well to keep them from hitting windows, too.
Feeder placement also can affect collision rates. Try placing your feeders very close to the window or at least 20 to 30 feet away from the window. Birds that visit the feeder close to the window will become acclimated to the window's surface and will be less likely to collide with the glass.
Reducing or eliminating bird collisions at your home doesn't require draconian measures. No one should have to cover their windows with electrical tape or other materials. Begin your bird-proofing by inspecting your home and identifying the windows most likely to be bird hazards. Look for larger windows that reflect outside scenes or those through which birds can see habitat. We lost a beautiful male cardinal this fall when I propped open our storm door for an afternoon. The glass was so clear that the cardinal could see right through to the other side and didn't realize there was a glass barrier.
Whatever solution you choose, I know you will agree it is a small price to pay to help protect birds around your home. After going to all the effort of planting trees for food and shelter and providing a smorgasbord of feeders, it is heartbreaking to have the birds we attract hurt or killed by collisions with windows, especially when there are easy and fun ways to prevent this all-too-common source of mortality.