Bird-safe glass works by transforming window glass into a barrier that birds will see and avoid. Glass that can be considered safe for birds has patterns (visual markers) across the entire surface to mute or distort the reflections of surrounding elements. The patterning can be made from various design elements. Often the visual markers will follow what is known as the “2×4 rule”, but the closer the pattern elements are to each other, the more protection the pattern will provide to birds.

According to leading scientists up to 1 billion birds are killed every year due to colliding into windows.  Dr Daniel Klem who has been studying this phenomenon for more than four decades, shares his experience and knowledge on the subject in his white paper titled “The building industry and bird conservation”.   

Glass is a major threat to birds as it is invisible to them. Birds are deceived by the “transparency” and “reflectivity” properties of glass and that is the main reason why so many birds are killed. Birds are trying to reach vegetation or the sky which are either located on the other side of the glass structure or reflected on its surface.  There are ways to reduce the number of collisions by creating a pattern on the first surface of the glass. The testing methods and the discovery of the 2×4 rule are discussed in the “Technical design of bird friendly glass” document. 

Contrary to popular belief, bird collisions are not just a problem during migratory periods… but all year round! During migration the volume of birds increases by about 40% depending on the region. Therefore, twice a year, more collisions occur but the issue still remains all year long. Something can be done to significantly reduce the number of collisions. Many bird safe glass products exist, however, the most effective solutions are those that have visual markers (patterns) on the exterior surface of the window. 

Birds are attracted to light. Tall buildings reflect light, and/or are lit up at night, which attracts them to areas where they would not naturally want to be. Once they are at ground level, they are in great danger as they cannot see glass and will potentially fly directly into windows where they are either injured or killed. There are legislation measures that exist to help prevent birds from colliding into glass buildings and more details can be found in “Legislative measures”. The city of Toronto, was the first to incorporate bird-friendly guidelines into its green building standard.  

Bird deterrence legislations in North America are mostly driven by local authorities at the state, provincial or city level. Some of the best-known rulings in United States are the Standards for Bird-Safe Buildings in San Francisco, and of course the New York City Local Law 15. In January 2022, Illinois introduced its own Bird-Safe Buildings Act.

In Canada, CSA A460 provides a national standard. At the municipal level, the regulations found in the “Bird Collision Deterrence” section of the Toronto Green Standard (TGS) are an important influence on mandatory bird friendly rules. The city of Ottawa introduced their own set of Bird Safe Design Guidelines in 2020.

The glass industry established its position on bird friendly glazing with the National Glass Association’s publication of their updated Bird Friendly Design Guide, which supports the prescriptive approach to bird deterrent markers (2×4 rule). This method has proven to be reliable and effective in reducing the number of bird collisions against glass.

The number of cities adopting bird safe laws is growing rapidly. We suggest that you communicate with local authorities to see which ones are most relevant to your projects. You can also reach out your local Walker Glass Architectural Manager to assist you in finding the right bird friendly glass legislation.