How can I keep birds from hitting my windows?

A Black-and-white Warbler sits quietly and recovers after hitting a window. Photo by Laura Erickson via Birdshare.
A Black-and-white Warbler sits quietly and recovers after hitting a window. Photo by Laura Erickson via Birdshare.

After cats, windows are one of the deadliest threats to birds in America. Researchers estimate that between 100 million and 1 billion birds are killed by colliding with glass every year, in the United States alone.

If you’re selecting new windows while building or remodeling, if at all possible choose double-hung windows or other types with the window screens on the outside. If you’re putting up a large picture window and like the effect of small panes, putting dividers on the outside as well as the inside will also help.

But most of us are stuck with the windows we already have, or are limited in our options in selecting new windows. Sticking one or two decals on a window will not help. You might try one of these techniques, ranked roughly from most to least effective:

  • Cover the glass on the outside with window screening or netting at least 2–3 inches from the glass, taut enough to bounce birds off before they can hit the glass. The is the kind of netting that is effective for protecting birds from hitting windows is sold in garden stores to protect trees and shrubs. This netting should be drawn taut across the windows, 2-3 inches from the glass, or birds could get entangled. It shouldn’t hurt your view at all on vaulted windows set high up anyway, nor will it reduce the solar benefits at all significantly. But it will both make the windows a little more visible and act like a trampoline so when birds do hit, they’ll bounce off.
  • Cover the outside surface of the glass with a one-way transparent film that permits people indoors to see out, but makes the window appear opaque on the outside.
  • Place vertical strips of tape on the exterior glass, set no more than 4 inches apart, or cover the exterior glass with decals placed close together (no more than 4 inches apart).
  • Mark the glass with permanent paint or markers. Birds can see in the ultraviolet spectrum, but painting windows with ultraviolet markers usually helps for only a few days because most of these inks fade very quickly.
  • Install external shutters and keep them closed when you’re not actively enjoying the light or view.
  • If you have interior vertical blinds, keep the slats half open.
  • Window decals can work, but you must put up many, set only a few inches apart, on each glass panel. Sadly, birds do not respond to falcon and owl silhouette decals the way people once believed. Visit our Window Collisions page for more suggestions and photos of window treatments that help prevent collisions.
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