Natural Life

When Windows Kill

by Mary Thill

Birds that struck windows in Washington, D.C., fall 2012. Source: Lights Out DC and USGS

Few sounds are as sickening as the soft but heavy thump of a bird hitting a window. I was working in a carrel in the Joan Weill Adirondack Library at Paul Smith’s College this spring when a newly returned migrant mistook an expansive window next to me for sky. I caught a glimpse of a small, dark shape dropping to the ground. By the time I walked down a flight of stairs and out to the spot below the window, the creature had recovered and flown off.

Most of the time, a bird’s first encounter with glass is fatal. Collision with windows is the single biggest known killer of birds in the United States, according to the American Bird Conservancy and New York City Audubon. “No one knows exactly how many birds are killed by glass—the problem exists on too great a scale, both in terms of geography and quantity—but estimates range from 100 million to one billion birds each year in the United States,” the organizations report.

My father on his walk from the bus to his office in downtown Buffalo used to pick up warblers felled by a glassy tower during spring and fall migration. But it’s not just skyscrapers and libraries. Most window-kills are caused by houses. Hummingbirds, thrushes and other woodland birds can’t tell the difference between the reflection from your camp window and actual trees, sky and flowers.

Some homeowners compensate by sticking silhouettes of merlins on windows to scare off songbirds, but decals of any sort must be spaced densely to be effective.

One of the best methods for preventing window collisions is to install bug screens—practical in the Adirondacks.

A few other tips:

Move indoor plants away from windows

Place bird feeders within three feet of windows so birds don’t have a chance to pick up speed, or place feeders more than 30 feet from your home so it’s more obvious that windows are part of a structure

Break up reflections by painting directly on glass

Architects and conservationists are also coming up with structural solutions that are less disruptive to birds and to your view. If you are considering building new, these are especially relevant. Thanks to Leslie Karasin, at the Wildlife Conservation Society’s Adirondack Program office in Saranac Lake, for providing the resource links below and other background for this article.

New York City Audubon: Bird-safe building guidelines

American Bird Conservancy: You can save birds from flying into windows

Audubon: Minimizing window collisions

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