Windows: The Invisible Danger

From broken bones and beaks to severe head and spinal trauma, a window collision can have catastrophic results for a bird. Some birds are killed outright during the impact, and those that are only temporarily stunned may be taken by predators during their recovery period or die of internal injuries later. Colliding with a window is one of the most common injuries in birds affecting everything from tiny songbirds to hawks and owls. 

Northern Saw-whet Owl window strike

A Northern Saw-whet Owl injured by a window strike

Windows often look more like mirrors reflecting their surroundings including vegetation and open sky. This is confusing to birds, and they fly at full speed into the glass, completely unaware of its presence. Sometimes the birds see themselves reflected in the glass, and if it is breeding season, they may attack their own reflection as if it were a rival bird.

Window reflecting a tree and sky

Photo CC-BY-SA Damien Pollet

Birds may also strike windows that have no reflections. If you have windows in your house that are situated directly across the room from one another, it may create the appearance of a tunnel. A bird looking through the transparent glass will only see the vegetation or sky at the far end of the “tunnel” and may attempt to fly through it. 

Windows creating a "tunnel effect"

Photo CC-BY Nicolás Boullosa

There, however, are steps that we can all take on our properties to ensure that our windows are not posing an excessive danger to the birds with whom we share our space.

Making your windows safer for birds

The most appropriate method will depend on a number of factors including the size of the window, suspected cause of the window strikes, and your own personal preference.

Preparations

  • Begin by walking around the outside of your home and inspect your windows from different angles at different times of day. Windows that reflect bushes, trees, or sky pose the biggest threat.
  • Check to see if any of your windows make the tunnel effect. If a window has no reflection, but another window is lined up perfectly with it on the opposite side of the house, a bird may see this as a travel route.
  • In addition to the visual inspection, you should listen to what the birds are telling you. If birds have struck any of your windows in the past, you can be certain that the windows involved represent problem areas.
Northern Flicker 101779 window strike victim in ward cage 072910 KM 2

A Northern Flicker recovers from a window strike at PAWS Wildlife Center

Make the windows more visible

  • Stick window decals or other decorations on the outside of the window.
  • Make stripes on the window with bar soap or UV liquid.
  • Use anything else that will tend to disrupt reflections and cue birds in to the presence of a solid object.
  • Hang a colorful windsock, shiny foil or mylar strips, aluminum pie plates or other objects in front of the window. These objects will both obscure the view of the window’s reflective surface and provide distracting movement that may deter birds from coming in closer.

Bird netting

bird netting

Photo CC-BY-SA SaturninoOpi

  • Does not obstruct your view.
  • Is commercially available at most lawn and garden shops.
  • Can be stretched tight over a wood or metal frame and then placed over the window.
  • Does not eliminate reflections, so birds may still fly at the window.
  • There needs to be enough space between the net and the window to prevent a bird from coming into contact with the glass when it impacts the net.

Change the environment around the window 

  • Trim back branches or shrubs that are near the windows this may reduce reflections that would attract birds.

If you find a window strike victim

  • Scoop it up with a shoebox or another dark container. Make sure that the container is well ventilated before placing the bird inside.
  • Put the box in a warm, quiet spot away from human noises, pets, predators and other dangers.
Black headed Grosbeak 102327 window strike 090910 KM 1

A Black-headed Grosbeak recovers from a window strike

  • If the bird was not badly injured, it will likely recover within an hour or so, be sure to take it outside (preferably away from windows) before checking on the bird. If you are keeping the box inside if the bird has recovered, it may burst out of the box as you open it. It’s better that this happen in the yard rather than inside the house.
  • If the bird has obvious injuries when you first discover it (blood is visible, a wing or leg has a visible break, etc.), or if it does not recover within two hours of being placed in a box, it may need help from a wildlife rehabilitator.

For more tips

15 Products that Prevent Window Strikes