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Bird-friendly glass

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Bird-friendly glazing

Help prevent birds from colliding with windows and façades

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Building with glass blurs the boundaries between inside and out. It helps elevate aesthetics and the experiences of people. Yet while humans can use environmental cues to identify glass as a barrier, there is a growing realization that birds cannot. In the United States alone, researchers estimate that up to two billion birds die each year due to bird-window collisions1

Birds are a significant part of the natural and built environments where we live and thrive. That’s why there is growing interest and increasing regulations around glass design that meets a project’s aesthetic, safety and performance requirements – while also helping to protect birds.

1 Klem, Daniel, et al. “Evidence, Consequences, and Angle of Strike of Bird–Window Collisions.”
The Wilson Journal of Ornithology, vol. 136, no. 1, 2024, pp. 113–119, https://doi.org10.1676/23-00045.

What are the benefits of bird-friendly glass?

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Collision deterrence

Adding visual contrast to the glass through various methods creates a visible marker to birds, helping them detect the glass as a physical barrier and avoid it. The effectiveness of the solution depends on the technology used as well as the size and spacing of the pattern elements. The building’s surroundings, lighting conditions and the outside reflectivity of the glazing also play a role in the solution’s effectiveness.   

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Depending on the technology, bird-friendly glass solutions can be more or less visible to humans from the outside of the building. Bird-friendly glass treatments can be used as design elements to make a statement, or they may be more subtle for a minimalist look. From inside the building, the visibility of a bird deterrent depends on lighting and the complexity of scenery outside. Many patterns are designed to virtually disappear when viewed from a distance.

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Energy performance

Bird-friendly solutions can be combined with high-performance coatings to provide thermal insulation and solar control properties to the glazing. These coatings can help maintain a comfortable temperature inside the building by reducing the amount of solar energy that enters through the glazing in the summer, or of heat escaping it during the winter.

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Environmental stewardship

Birds play a critical role in ecosystems and economies around the world. Between providing food, controlling pests, enriching soil and other contributions, their impact on quality of life is immense. With many bird populations in decline, it becomes even more serious to address the problem of bird-window collisions. Bird-friendly glass can also contribute to LEED® Innovation Credit (“Bird Collision Deterrence,” BD+C: New Construction. v4.1).*

*Scott R. Loss, Sara S. Loss, Peter P. Marra and Tom Will, Bird–building Collisions in the United States: Estimates of Annual Mortality and Species Vulnerability, The Condor: Ornithological Applications in January 2014.

Why do birds collide with glass?

Bird-window collisions can happen anywhere birds and buildings are present. In fact, low-slung buildings in the suburbs account for a much higher percentage of total bird-window collisions. 

Most often, birds collide with glass buildings and windows because they don’t perceive glass as a barrier. This is a result of reflective and transparent qualities of glass, as well as building design and lighting.


Birds often mistake reflections on glass for extensions of their environment. Even glass with lower reflectivity can act like a mirror. When the reflection of light outside is brighter than the building’s interior, birds will see mostly the outside world reflected back at them in the glass.



When the building’s interior is brighter than the outside reflections, birds will see mostly the transmitted view to the inside creating a direct line of sight from one window to another (e.g., walkways, corners, bus stops or transparent wind/sound barriers). Birds may attempt to fly through, causing a collision. Also, birds may see wooded atriums or indoor plants as an inviting habitat. 



Building shape, location and landscaping can have a significant impact on the collision risk as well as the maximum effectiveness of deterrents. For example, curved or U-shaped buildings can funnel birds into an environment that confuses them and makes it challenging to get around or away from the building. 



During migration periods, the sun’s light plays an important role in telling birds when and where to fly. Most birds migrate at night and regain strength during the day, using the night sky and ambient light levels to aid their navigation. Urban light pollution can confuse this instinct for a bird in flight – and sometimes an entire flock. Exterior lighting, especially at night, can appear as an artificial sunrise, luring and trapping birds. Birds can also gravitate toward interior lighting, which can cause them to collide with the glass in an attempt to fly through it.


What Guardian Glass solutions help counteract collisions?

Tested by bird conservationists for proven effectiveness, Guardian bird-friendly solutions pair with your favorite SunGuard™ low-E coatings to help meet the energy performance requirements and support LEED® Innovation Credit for Bird Collision Deterrence qualification. Deciding which solution to use can depend on project criteria for cost, aesthetics and performance.

  • Bird1st™ EtchThis solution can be the best option for a visible pattern that is translucent rather than opaque. It is applied on surface 1 with a low-E coating on surface 2 for best performance results. This solution is available in multiple acid-etched patterns designed to help deter bird-building collisions.
  • Bird1st™ UVThis solution typically has the least impact on human visibility and aesthetics. It helps protect birds while preserving clarity and views with advanced UV technology that builds on differences in human and avian vision. Under most conditions, the UV pattern is visible to birds yet almost undetectable to humans.**
  • Bird-friendly fritted glass - This option is usually the most visible to the human eye and offers the greatest data around efficacy in protecting birds. Frit patterns can also be the most economical solution in new projects. 

**The UV stripes are more pronounced when the glass is wet or when condensation forms. Surface residue can also make the stripes more visible.

Penn Medicine, Location: Radnor PA, Architect: Ballinger Architects
Penn Medicine

Guardian SunGuard

Paired with select Guardian SunGuard low-E coatings, Guardian Bird1st glass delivers on helping to create structures mindful of aesthetic and performance standards.

How do these solutions work?

Guardian Glass bird-friendly solutions visually signal an impending barrier to birds, helping decrease collisions as confirmed by acceptable Threat Factor scores from the American Bird Conservancy (ABC). Threat Factor indicates the percent of times in which birds will not avoid collision. ABC defines “bird-friendly” materials as having a Threat Factor ≤30.

Guardian bird-friendly solutions feature patterns strategically spaced at least 2" x 4" or 2" x 2" apart. The ABC champions the 2" x 2" Rule for the spacing of visual elements in order to effectively deter even small birds from collision, noting that 2" x 4" spacing of such elements can also significantly reduce collision for most species.

Test your knowledge about bird friendly glass solutions

Do you understand birds’ physiology and behavior, which are key elements in the development of our bird-friendly glass solutions? If not, we suggest you learn more about this topic thanks to our 10-question quiz!

Test your knowledge about bird friendly glass solutions

Our bird-friendly glass solutions

  • Guardian Bird1st™ UV

    Guardian Bird1st™ UV

    Guardian Bird1st™ UV is a highly innovative, bird-friendly glass that helps to prevent bird collisions with buildings. It uses a UV coating that has a striped pattern almost invisible to humans but visible to birds.

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  • Guardian Bird1st™ Etch

    Guardian Bird1st™ Etch

    Guardian Bird1st™ Etch glass helps to prevent birds from colliding with buildings – by featuring striking and highly visible acid-etched patterns. With a choice of four distinct patterns the glass also offers enhanced design flexibility on façades and curtain walls.

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We can help meet your bird-friendly ambitions
With different priorities, geographic considerations and legal requirements, every bird-friendly architectural project is unique. Guardian can help you choose and specify the glass solution that's right for you.