Ever found a beautiful bird dead outside your home? Chances are it smashed into your window and never recovered. For every dead bird you find, just imagine how many were snatched up by a cat or pulled into the brush by some other critter. Worldwide, window collisions kill close to a billion(!) birds every year. With spring migration currently underway in the northern hemisphere, now is as good as ever to make your home bird safe. The DIY experts at Stack Exchange tell you how.

The NYC Audubon Chimes In

After habitat loss, the greatest threat to wild birds may be glass windows.

NYC Audubon started Project Safe Flight in 1997 to address the issue in New York City. Daniel Klem, an ornithologist at Muhlenberg College, estimates that close to a billion birds are killed every year by flying into glass. A study he conducted, with NYC Audubon, found 1.3 birds killed per hectare per year in an urban setting, which works out to over 90,000 birds per year in New York alone.

All bird species are vulnerable, although migratory songbirds are the main victims. Most are killed instantly, but others succumb when they are stunned and fall prey to gulls, rats, or other predators.

We have rescued over 1,200 birds, persuaded buildings to retrofit their more dangerous windows, and published Bird-Safe Building Guidelines to help architects and designers develop solutions in new buildings.

Private homes as well as skyscrapers endanger birds. Most home owners have heard the unpleasant thump that means a bird has hit a window; many have also found bird carcasses near their windows. Birds do not see the glass as a solid barrier; they see reflections of trees or sky or a fly-through to open space beyond. This should come as no surprise, since even people occasionally walk into glass doors. For a person it is merely embarrassing, for a bird it is often fatal.

Homeowners can reduce the collisions and save bird lives in a number of ways:

- Bird feeders should be placed within three feet of a window, so that birds visiting the feeder cannot get up enough flight speed to hurt themselves.

- Installing a pattern on a window where birds are known to hit can be uncomplicated and inexpensive. Patterns with negative space no greater than 4 by 2 inches, the size of a hand, are most effective.

- Decals of hawks or other raptors are not particularly successful, unless the decals are spaced very closely— and then it doesn't really matter if they are of birds of prey or an abstract design.

Some suggestions for temporary or seasonal fixes:

- Place vertical tape strips at a maximum of 4 inches apart or horizontal strips a maximum of 2 inches apart. ABC BirdTape, is long-lasting and more aesthetically pleasing than masking tape or electrical tape, though all are effective. Be sure to place the tape on the outside of the window for maximum effectiveness.

- Soap windows, or use window paints or tempera paints to obscure most of window.

- Purchase or make your own window gel clings. Be sure to space them no more than 4 inches apart horizontally and 2 inches apart vertically.

- Draw blinds and move indoor plants away from windows. This will not work if there are strong reflections of the landscape in the window.

For more permanent fixes, ones that keep birds from striking glass or lessen reflectivity and transparency, we suggest:

Install a frosted or opaque window film. Collidescape is a film that looks opaque from the outside, but allows views out. Films are most effective when applied to the outside of the window. Most films are not guaranteed when placed on the outside surface, but many are reasonably long-lasting on these surfaces.

- Install unobtrusive netting in front of window. A company called Bird B Gone has designed several types for glass windows and facades.

The ultimate solution would be a glass that is visible to birds but not humans. A product called Ornilux Mikado, manufactured in Germany by Arnold Glas, incorporates an ultraviolet spidery crisscross pattern within the glass visible to birds but nearly invisible to us.

Watching birds and nature from inside your home should be a pleasure. Bird fatalities are an unintended consequence of home design. But with some creativity and imagination, you should be able to see your birds and keep them safe.

Answer: More Options

There are two reasons birds fly into Windows, either they can't see the glass or they see a reflection in the glass. The only real solution, is to make the window more visible or less reflective.

Unfortunately, making the window more visible to birds also makes it more visible to humans. So the solution may not be exactly... um... fashionable.

One solution: put decals, tape, paint, marker, or some other type of markings on the windows. You could also try hanging wind chimes, or other decorative items inside/outside the window.

Another solution that seems to be successful, is to hang fine mesh over the windows. The theory here is that the mesh will reduce the reflection on the windows, so birds will be less likely to think they are flying into whatever is reflected in the window.

The good news is, you may only need to do this during migratory seasons< (spring and fall). So you could pick up a window paint marker (~$5.00), and draw lines, squiggles, or patterns on the windows during migratory seasons.

You could try making up some detachable screens for the exterior of the windows, and put them up during the migration season. This might be a less noticeable solution.