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The Spokesman-Review Newspaper
Spokane, Washington  Est. May 19, 1883

Reason for bird fatalities clear as glass

Picture windows that enable us to enjoy nature from the comfort of our homes can be deadly to the birds we love to watch. And that’s putting it mildly.

Ornithologists estimate that in North America alone, 100 million to 1 billion birds a year are killed in collisions with windows or towers, said Laura Erickson, science editor for the Cornell Lab of Ornithology.

That’s about twice the carnage caused by free-roaming cats, and maybe a thousand times the toll taken by hunters.

The problem was driven home last weekend when neighbors called me to admire and identify a beautiful young hawk that had met its maker in a large pane of glass above their front door.

With the help of a falconer who weighed the bird at 23 ounces, we were able to rule out the possibility it was a female Cooper’s hawk and identify the victim as an immature male goshawk. The predator likely was attracted by the quail at a backyard feeder.

With a twinge of angst, we all admired the hawk, limp and lifeless but still warm and pristine, from its hooked beak to its lavishly feathered thighs. Bare yellow legs and toes were spiked with sharp polished-black talons.

“We’ve got to do something about our windows,” said my neighbor, looking at the expanses of glass around their lovely home. “We have all kinds of birds hitting the windows all the time.”

My God, I thought: If I stepped out on my porch with a shotgun and blasted a few songbirds every day, the neighborhood would be rightfully outraged.

But we’re all so nonchalant about the passive and indiscriminant killing of birds that collide with our homes.

“We suspect that even a high percentage of the birds that fly away after a window strike don’t make it,” Erickson said.

Famed bird artist and guidebook author David Sibley has taken a keen interest in window collisions. Behind habitat loss, windows are a leading human threat to birds even though they may be among the easiest threats to tame.

Taking a scientific approach at the window facing his bird feeders, Sibley’s recorded as many as six bird strikes in 1 hour, 40 minutes. His experiments with deterrents can be found on his blog at www.sibleyguides.com.

The most detailed research on the issue has been done by Daniel Klem Jr. of Pennsylvania, who searched the scientific literature to find studies ranging to the 19th Century.

The earliest account Klem found of a bird hitting a window in North America dates back to 1832. “A sharp-shinned hawk, which, in the pursuit of prey, flew through two panes of greenhouse glass only to be stopped by a third,” he said.

Modern architecture’s liberal use of glass and reflective materials has exacerbated the problem.

“All the glass in modern high-rise buildings has become a major problem for birds,” Erickson said. “Since most songbirds are nocturnal migrants – they even use stars for navigation – they can be disoriented by lights in their airspace. We get huge bird kills at communication towers and high-rise buildings.

“It’s very troubling, since these are indiscriminant killers that take the healthiest of birds, the ones that are flying strong. Groups in many cities, like Seattle, are trying to get building mangers to at least use curtains or turn off lights during migrations.”

But bird collisions shouldn’t be shrugged off as somebody else’s fault. Most homeowners have impact on birds, pardon the pun – especially the estimated 46 million birdwatchers who use feeders to attract birds to their yards.

The more glass you have, the bigger the threat.

Erickson summarizes some techniques for making homes safe for birds in her book, “101 Ways to Help Birds,” and there’s no shortage of advice on the Internet. She recommends www.flap.org.

Electronic devices that emit high frequency sounds or magnetic fields have promise, but tests seem to be inconclusive, say Sibley and other students of the issue.

Several manufacturers make screens or different deterrents that can be effective. Two notable products are Birdscreens and CollidEscape film.

Hawk silhouettes do not deter other birds, most experts agree.

Do-it-yourself bird deterrents for windows endorsed by many experts include:

•Drape or tack small-mesh netting or install Birdscreens over the outside of the most problematic windows. Many experts say this is the least attractive but most effective method.

•Attach strands of monofilament (fishing) line about 3 inches apart on a board and mount the board outside above the window so the strands hang vertically about 3 inches apart. On his blog, Sibley says this seems to work.

•Move bird feeders. One school of thought says move them at least 30 feet away. Another says keep them within 3 feet of the window so confused birds will not be able to reach terminal velocity before smacking the glass.

•Hang strips of Mylar tape or ribbon vertically in the window, no more than 4 inches apart. (Note that vertical line or ribbons may have to be anchored to a board top and bottom to avoid being blown away from the window and rendered ineffective by winds.)

•Hang a plant outside the window. (A plant inside the window may attract rather than deter birds from hitting the glass.)

•Decorate the windows with decals, cutouts, dots or the like, but keep them no more than 4 inches apart.

•Be creative with combinations of decals inside the window and windsocks, weather vanes, CDs and ribbons hanging and moving with the wind outside the window.

With all the options available, don’t wait for the wake-up call of another “Thunk!” on the picture window.

You can contact Rich Landers by voice mail at 459-5577, extension 5508, or e-mail to richl@spokesman.com.