Laura Erickson's For the Birds

Conservation: Make your windows safer for birds.

Thud! How many of us cringe when we hear that sound—another bird smacking into our picture window? Sometimes the birds fly off immediately or after a short time, but often these birds have suffered hairline skull fractures or develop clots that kill them within hours or days. Intensive studies have shown that half of all birds that hit windows end up dying, either directly from head or neck injuries or from predation or accidents occurring while the bird is stunned. Many times when I was rehabbing wild birds, people brought me woodpeckers that they thought were going to be fine because the birds seemed alert and could move their wings, but on examination I’d discover that the birds’ necks were broken or their spines permanently damaged and the birds were incapable of any controlled movement whatsoever.

Window strikes may happen only once or twice in a year at some windows while similar windows in other locations may kill hundreds of birds a year, particularly during migration or during seasons when birds are concentrated at feeding stations. Multiply this by all the windows in America and the issue becomes staggering. Dr. Daniel Klem Jr., an ornithologist at Muhlenberg College, stated in a February, 2004 article in CNN.com Science & Space, “Glass is ubiquitous and it’s indiscriminate, killing the fit and the unfit.” Klem estimates that collisions with glass kill up to one billion birds in the US alone, and estimates that only habitat destruction kills more birds.

Dr. Klem has been researching different ways of manufacturing glass that will make it more visible to birds. Glass etched with fairly closely-spaced dots or other patterns may help birds see it while not detracting from the aesthetic qualities of the window. But more research must take place before a truly bird-safe glass is found, and this takes time and money. Only when consumers start demanding bird-safe glass will manufacturers go to the trouble of funding such studies and changing their manufacturing practices.

People have known that window glass can kill birds since at least 1832, when the earliest published account I could find of a bird hitting a window in North America was written by Thomas Nuttall in A manual of the ornithology of the United States and of Canada. He described a Sharp-shinned Hawk (Accipiter striatus) which, in the pursuit of prey, flew through two panes of greenhouse glass only to be killed when he hit a third. But until Dr. Klem started researching the magnitude of the problem, ornithologists and conservationists have focused on other issues they judged to be more important. Now, as researchers such as Dr. Klem gather more data about the horrifying magnitude of this problem and search for viable solutions, perhaps one day soon all new windows will be made from a more bird-safe material. Dr. Klem closes the CNN.com article with these words: “The heart of this is to get a piece of glass that will solve this problem. We can’t say that we have that yet. But I’m more encouraged than ever that we can come up with a solution that will stop this senseless slaughter of wildlife.”

While we wait for better, more permanent solutions, we have to figure out how to minimize kills at our own windows. Whether the glass is clear or reflective, birds simply don’t see it. What can you do to make your own windows safer for birds?

Be careful where you place your feeders. Feeders placed on the window glass or within two or three feet of the window are safest. Birds feeding in these are more likely to actually see the glass, and even if they don’t, when they take off from a window feeder they aren’t going at top speed for at least a few wing beats. When feeders are close enough to the windows for us to enjoy watching the birds, but farther than this, window kills are inevitable.

• Make the window more visible. Things that can help birds to notice the glass in some situations include:

o vertical exterior tape stripes not more than 10 cm apart
o interior vertical blinds with the slats half open
o soaping the window
o decals, sun catchers, and other objects.

• Put something outside the window glass that absorbs the impact. Window screens or netting set on the outside of the glass can work very well, if set three or four inches from the glass and taut enough to actually “catch” the bird and bounce it off, like a trampoline, before the bird reaches the glass.