Bird friendly glass
Bird-friendly glazing
Up to one billion bird deaths in the United States are attributed to collisions with buildings and other structures each year1. This document provides information on the problem, its relation to building glass and glazing, and offers potential solutions for architects, contractors, and fabricators. As the architectural community and glass industry work to address this issue, it is critical for audiences to understand collision causes, product testing, bird behavior, and solution options.
1The Condor: Ornithological Applications, 2014
Why do birds collide with glass?
Cities with a density of building structures, including high-rise, can be the site of nighttime bird collisions due to interior and exterior lighting. Flocks of migrating birds can collide with large buildings and this generates headlines and attention. However, suburban, low-rise buildings account for a much higher percentage of collisions; individual collisions may not be as evident but can happen more frequently. In general, there are four ways buildings and building environments contribute to bird collisions:
Reflection
Birds cannot differentiate between actual and reflections of tree, sky, or habitat. Even lower reflecting glass can act like a mirror when it is bright outside and dark inside. When coupled with certain façade designs, the reflections can create areas that are visually confusing to birds. Reflective materials that provide adequate image formation, pose a danger to birds.
Transmission
When there is a direct line of sight from one window to another (e.g. walkways, corners, bus stops, or transparent wind/sound barriers), birds do not perceive the glass as a barrier, and may attempt to fly through, causing a collision. Also, birds can see wooded atriums or indoor plants as an inviting habitat.
Design
The design of the building and its location can have a significant impact on the collision risk as well as the maximum effectiveness of deterrents. Building shape, location, and landscaping (especially the anticipated height of the tree canopy once mature) all have considerable impact on the collision risk profile of the facility.
Lighting
Birds use the night sky and ambient light levels to aid their migration navigation. This causes nighttime collisions as lighting inside buildings, especially those buildings with potential habitat, attracts birds. Artificial lights, particularly those that point upward, can lure and trap birds in their haze, where they potentially fly to the point of exhaustion.
How to help prevent birds from flying into windows?
There are three different preferred ways to treat glass that range in visibility to humans which all been shown to be effective for bird-friendly applications. Deciding which to use is be based on the project criteria for aesthetics, cost and bird safety.
- Fritted Glass—This option is the most visible to the human eye, and therefore can offer the most data around efficacy in protecting birds (if humans can see it, birds can too). Frit patterns can be the most economical solution in new projects. However, frit will tend to obstruct more of the occupant view than some other solutions.
- Etched Glass—This includes different common means of treating the glass, so it is translucent. It is moderately visible to the human eye.
- UV-coated Glass—This option provides the least impact on human visibility and aesthetics. Humans only see in the visible light spectrum while some birds see in the UV spectrum in addition to the visible spectrum. UV coatings provide a visual marker that can indicate a potential obstacle to birds.
Note that these treated glass deterrent applications primarily address daytime collisions, although frit may help with nighttime collisions too.
Tested to be bird friendly
Guardian Bird1st™ products visually signal an impending barrier to birds, helping decrease collisions as confirmed by the acceptable Avoidance Index score from the American Bird Conservancy (ABC).
To further defend birds, Guardian Bird1st™ adheres to the 2" x 4"* rule accounting for different bird sizes and species.
*2″ x 4″ rule: Design that accommodates two inches or less of horizontal space or four inches or less of vertical space between etch markings
Paired with select Guardian SunGuard® low-E coatings, Guardian Bird1st™ glass delivers on creating smart, beautiful structures cognizant of various performance and energy standards.
Bird1st products may meet LEED Pilot Credit 55 and Toronto Green Standard Bird Collision Deterrence values.
Bird-friendly Glass Expert Knowledge
