Birds and windows

I had a traumatic morning, but not as traumatic as it was for the bird who hit my window. After a loud thump, I knew what had happened. We’ve had a few birds tap the window before but this one didn’t sound good. Sure enough when I looked outside the bird was alive but on the ground and struggling. I did what I could and the bird did get back to its feet and hopped over to sit under the spruce tree in my yard. I am hopeful but also doubtful that he will survive. This has me wondering what I can do to help protect the birds in the future.

It is well known in the bird research community that commercial buildings have a pretty significant and negative effect on migratory birds but apparently the impact of residential properties is not as well understood. A group of researchers at the University of Alberta used citizen science to try to get a handle on the impacts. Individuals responded to a survey about number of window collisions and mortality rate. Not surprisingly birds run into rural homes more frequently than urban ones and windows at homes that have feeders more often than those without. 38% of collisions resulted in a fatality.

With bird hits being a problem (39% of the respondents said that at least one bird hit their window in the past year) and mortality being fairly significant (another group of researchers estimated that 25 million birds are killed in Canada by hitting windows, with houses making up the majority because there are simply more houses) what are the best ways to protect the birds?

In an older study, Klem found that single or widely spaced objects or patterns on windows did not significantly affect the number of bird hits. To be effective the objects or patterns needed to be placed no more than 5 to 10 cm apart and cover the entire window. You can also move objects like feeders significantly away from the window. If this isn’t possible then the feeders should be placed within 30 cm of the window. This way the birds come in but not with the same speed/force.

More recently, Klem and Saenger found that UV signals can be used so long as they reflect at least 20-40% of light within wavelengths of 300-400 nm (these are wavelengths that we can’t see but birds can). They also tested hanging parachute cord in front of windows separated by 8-11 cm and found this method effective. This study (and others that it was based on) indicate that the most effective methods involve changing the outer surface to break up the reflection of trees and sky.

There are a wide number of commercial products that can be installed. They either make the window visible (grid of objects/pattern/UV reflection) or they create a barrier in front of the window that the birds try to avoid (similar to the parachute cord). It’s a matter of choosing what both you and the birds can live with.

Here is a page that describes several different products and provides tips on how to use them effectively.

On the Flap Canada site you can learn about different methods of making your windows visible and report collisions.