Thud! I hear a dreaded noise against my front window and know at once that a bird has flown into it. My large back window has a netting, summer and winter, to warn away birds, but up to now my front picture window has not been a problem. The only preventive methods used there are bird silhouettes placed on the outside of the glass, but after a year of being up, their effectiveness is gone.
The main cause of window strikes is reflection. Birds are sensitive to polarized windows and may not see the glass, or they may see trees reflected or open sky or clouds, and fly towards those, especially if startled or seeking cover. Go outside and look at your own windows; if you can see the sky or trees reflected there, so can birds.
Estimates for North America suggest that 100 million birds may die from window strikes each year. There are a number of ways we can make our windows less dangerous to birds without reducing our view too much, including shade cloths, netting and decals. Even just keeping blinds slightly closed or white shears drawn will help reduce reflection.
Lightweight netting, available at hardware or bird stores is a method my husband and I have used for several years. Using a simple frame at the top and bottom, the netting definitely helps reduce bird strikes. To be effective, it should hang tightly at least two inches from the glass.
Window decals, available at bird stores or on the Internet, are another method we have used. WindowAlert decals contain a component that reflects ultraviolet sunlight (invisible to humans but glows like a stoplight for birds). They are placed on the outside of windows, but a single decal will not work. You need to use several per window, placed about four inches apart, and they should be replaced every year. These can be found in various decorative shapes, such as hummingbirds and butterflies.
Some people swear that hawk silhouettes are most effective. You can buy these, or make your own, using black poster paper.
A transparent film called CollidEscape which is applied to the outside of a window is sometimes used and this apparently reduces reflectivity and transparency. It is used mainly for commercial and retail advertising on glass.
Some items people try that are not very effective are: a plastic owl placed near a window (birds soon learn that this means nothing) and noise deterrents.
A new method which we are trying this year is called “Acopian BirdSavers.” These consist of parachute cord hung at about four-inch intervals from a horizontal support such as a Vinyl J Channel, wood moulding, or aluminum extrusion. For about $70 my husband has bought the material and constructed enough for all the windows of our house. We bought the cord from Stapleton’s Great Adventure Company in Regina. Instructions and details to buy the already constructed product are also available online at birdsavers.com.
If a bird does strike one of your windows, do not handle it unless necessary. It might just be stunned and may fly off later. In winter, or if there are predators (such as cats) around, put it in a box, close it up and keep it quiet for an hour or so. If you believe it hit really hard, or if it still seems disoriented, call a rehabilitator if there is one near. The bird may have a severe concussion which can be fatal, but anti-inflammatory medication sometimes helps. In southern Manitoba, contact the Wildlife Haven Rehabilitation Centre in Ile des Chenes (204-878-3740).