Saturday, February 5, 2011

Window Bird Collisions

It’s probably happened to you. You’re enjoying the view of watching birds at your backyard bird feeding station when suddenly they spook due to a Cooper’s hawk. They burst, scattering in all directions and one bird, let’s say a white-throated sparrow, sees a small opening of sky and bushes and heads for it in order to escape. It’s a fatal mistake. Although the sparrow avoided the clutches of the hawk, the small natural opening that it thought meant freedom turned out to be the reflections of a window. The sparrow hits it with full force, partially breaking its bill and hemorrhaging its brain. You’ve heard the thud and run outside to check on it and find it dead beneath the window. But make no mistake, even if the bird has flown away, chances are it will perish from its injuries. This sparrow can now be added to an annual tally of birds that have died from colliding into windows and buildings which conservationists estimate ranges between 100 million and 1 billion birds a year; this cause of mortality ranks among the top three causes for bird decline among North American birds and may be the number one quantifiable cause.

A variation of this experience happens with larger commercial buildings. With both the use of glass in general, and the use of reflective glass as the main type, growing in popularity, many glass-facaded commercial buildings have become significant sources of bird mortality. This problem is magnified when trees are planted near the building. Migrating birds see the reflection as reality, and seeking the sky or tree the reflection presents, unwittingly fly into the glass with lethal force. Unfortunately, it is not unusual for dozens of birds to perish at problematic buildings as they navigate on migration through urban centers like New York, Boston, Chicago, Toronto, and San Francisco. Long Island buildings pose a problem too. Fifty two golden-crowned kinglets, several warbler species and yellow-bellied sapsuckers died in one day flying into an all-glass building situated in Great Neck as they migrated south this past October. All-glass buildings at the Jericho and Huntington Quadrangles are also known to kill birds.

Fortunately, there is a technological answer to the problem. Unlike humans, birds can see ultraviolet light. Window and window film manufacturers are taking advantage of this ability by making windows and easily applied window films that reflect UV light. Windows so equipped, instead of deceiving birds, inform them that the windows are solid objects that should be avoided. And since we cannot see UV light these solutions pose no aesthetic concern.

The Huntington-Oyster Bay Audubon Society is working with New York State Assemblyman Steve Englebright (D-Setauket) to introduce legislation in the 2010 NY State Legislative session to begin to address this issue. While all the elements of the draft legislation have not been finalized, it is expected to require new public and private construction to use bird friendly window designs, and to establish a 15-member Bird Friendly Building Council charged with researching various issues relating to the problem and developing proposed solutions, including a program to retrofit existing “problematic” buildings. We’ll keep you informed as this important legislation takes shape over the next couple of months and works its way through the state legislative process.

And what to do to prevent that white-throated sparrow from becoming a victim at your home? Here are several things you can do to deal with window collisions:

  • Because collisions are caused by birds attempting to fly through glass, or because they see the reflections of the sky and trees and are unable to recognize the glass as a solid object, be sure to break up or eliminate their view by placing decals on your windows, ideally one-quarter-inch wide, white, vertical stripes spaced four inches apart, or one-eighth-inch, black, horizontal stripes spaced one inch apart.
  • If you feed birds in your yard, move the feeders and bird baths to within three feet of your window. The birds cannot gain enough momentum at this close range and you greatly decrease the chance that they will get hurt. If this is not possible, move them at least thirty feet.
  • Move inside plants away from windows so that birds do not mistake them for outdoor habitat.
  • Consider using screens, bars or film on your window to eliminate reflections. If you can, purchase bird safe glass to have installed.
  • If you are landscaping your yard, try to place trees and shrubs away from your windows in order to prevent reflections in the glass that look like a continuation of your yard.
For more information on how to make your home bird friendly, please see: and

John Turner/Stella Miller

No comments:

Post a Comment