On sunny days, glass can be so highly reflective that humans as well as birds are fooled into thinking that they are looking at open sky, trees, or other scenes in nature. This is a serious hazard for birds, which are often injured or killed in collisions with window glass. Photo by MIROSLAV VAJDIC for openphoto.net CC:Attribution-ShareAlike
WITH SPRING WE OFTEN GET LOTS OF BRIGHT, SUNNY DAYS--good for gardeners, but not always so good for birds, who may crash into windows that are reflecting what look to them like beautiful open skies. If you have this problem, here are a few tips to help you and the birds do better this year.
Why they do it
Typically birds fly into windows for one of two reasons: 1., the window is reflecting sky or trees or some other scene the bird thinks it can fly into or, 2., the bird sees real daylight through a window and thinks it can fly through to the other side.
Situation number 2 is fairly easy to prevent. The trick is to avoid having uncurtained windows either directly opposite one another or kitty corner from one another. So for instance, if you have a large open living area with windows that face each other on the north and south sides of the house, make sure that the windows on one side are always covered with curtains. That way a bird will never get the idea that it can fly through your living area and come out safely on the other side.
Situation number 1 is more difficult. There are only two ways to deal with this situation. One is to put up a barrier that prevents birds from hitting windows. The other is to make your windows reflect less light.
Upon reflection ...
Let's look first at ways to make windows less reflective.
The easiest way to make your windows reflect less (and definitely the one that appeals to me) is just to let them get dirty. The dirtier the windows get, the fewer bird strikes you'll have.
Don't want to wait several years for your windows to get seriously murky? You can soap the outsides. Yes, people do this.
If you want clean windows, however, preventing bird strikes gets harder. But here are some ideas. I can't guarantee that any of these will work every time, but they probably will help to prevent at least some window strikes.
Idea number one: Glue small stick-on decals or use window clings (which are a lot easier to remove) all over the outside of the window, placing them about 8 inches apart. Yes, they have to be on the outside because putting them on the inside won't prevent the window glass from reflecting light. And yes, they do have to be that close together because if they're not, birds may try to fly between them. The window clings sold under the brand name of Whispering Windows are bird-themed and quite attractive.
Don't want pictures on your windows? Idea number two: Some people try hanging strips of shiny tape, often referred to as bird-scare tape, in front of windows. In theory the fluttering tape frightens birds so that they stay away from areas where it is hanging. (This trick is also used to scare birds away from orchards.) The Wisconsin Humane Society even sells a holographic bird-scare tape.
Idea number 3: For those who want a more conservative look, there is now a product called CollidEscape. It is a film that can be applied on the outside of window glass. I haven't tried it myself, but supposedly it makes the window glass much less reflective. From the outside (in the pictures anyway), it looks like a very tidy-looking version of soap. However, unlike soap it allows you to continue to see out the window, or so the manufacturer claims. Warning: This stuff is expensive: $3/square foot if you are referred through the Fatal Light Awareness Program, a worthwhile organization that is working to preserve the lives of migratory birds in urban areas.
Another technique is to put up a barrier that you can see through but that birds will bounce off of.
If you're a do-it-yourself type and your house lends itself to this modification, you may be able to install fine garden-protection netting from below your eves to below the windows. The netting will be almost invisible from inside the house or from the street, and if it is taut enough birds will bounce off it without being hurt--you are, in effect, making a bird trampoline. You might have to stretch the netting on a frame before installing it in order to get the desired effect. Please note that if the netting is not taut enough, birds might get tangled up in it. The netting also must be far enough away from the glass so that the birds bounce off the netting without striking the glass.
If you'd rather not do this yourself, the Bird Screen Company makes fiberglass window screens that can be attached to the outside of a window using hooks and suction cups. I haven't tried this product, but according to the manufacturer, the hooks hold the screen far enough away from the glass so that birds will bounce off unharmed. Though pricey, this product is quite a lot cheaper by the square foot than CollidEscape is.
And the winner is ...
Dirty windows! But that's at my house. If I were going to try anything other than good old-fashioned grime, I'd probably give the fiberglass Bird Screens a try. They seem to be practical and good looking, and I think there's a good chance they would stop most if not all window strikes. If you decide to try any of these techniques, please let me know how they work for you.