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Bird-Building Collision Reduction:


Bird-building collisions occur most frequently in dense urban areas. During the day, birds see their habitat (trees, bushes, sky, water) reflected in the windows and reflective exteriors on buildings and fly towards them. Or they perceive clear passage through the transparent glass on linkways between buildings or through glass-walled solariums and lobbies. birds might also strike a window when they see interior, ornamental plants and trees through clear glass and try to take refuge there.

As architects, developers, building owners and managers, you have a corporate responsibility and a prime opportunity to influence the designs of new buildings, and to retrofit existing buildings to be BirdSafe™. As our urban environment continues to grow, so do the negative impacts it has on the natural environment. We all have a responsibility to try and lessen these harmful affects by adopting an ecological approach to planning, designing, building, and retrofitting our cities and towns.

The bird/building collision issue is now incorporated into sectors of the green building movement, i.e. the City of Toronto’s Toronto Green Standard and the U.S. Green Building Council’s LEED Bird Collision Deterrence Pilot Credit. Building aesthetics is important to everyone. Visual cues that birds need to avoid impact with glass are perceived to interfere with this demand, when in fact they can beautify a building’s facade. The moment one looks at glass as a canvas, the options for individuality and beauty become limitless.

The icons to the right highlight collision reduction strategies, supported by research, that offer cost-effective, durable, and aesthetically-pleasing solutions, while helping to provide a safer passage for migratory birds through urban areas. The key to BirdSafe™ buildings is to include these collision reduction strategies in building design, while making sure to correctly following FLAP Canada's Visual Marker Standards.

FLAP Canada Standard for Visual Markers

For most bird species visual markers are to be separated no greater than of 5 cm (2 inches) vertically and/or 10 cm (4 inches) horizontally. See below image
For smaller bird species (hummingbirds, kinglets, creepers, etc) markers should be separated by a maximum of 5 cm (2 inches) vertically and/or 5 cm (2 inches) horizontally.
Markers should stand out and offer the highest level of contrast on clear or reflective exterior surfaces under varying weather conditions.
The dimension of a visual marker pattern needs to be no less than 0.32 cm (1/8 inch).
Visual markers are to be applied to the exterior surface (first surface) of glass in order to disrupt the illusion of the reflected environment or open area beyond the glass.
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Strategies for Glass:

These collision reduction strategies are condensed from the City of Toronto's Bird-Friendly Development Guidelines. The guidelines were published in 2007, in close partnership with the Fatal Light Awareness Program. FLAP's expertise and research findings helped set the parameters for these bird-friendly strategies.

The guidelines emphasize visual markers on windows as the most effective collision reduction strategy. While other techniques suggested in the guidelines help lessen the threat (i.e., angled glass, awnings, overhangs, louvers etc.), properly applied visual markers on windows potentially remove the need for employing other techniques.

For more detailed information on these collision reduction strategies, please email us at for information, advice, or to have your building(s) assessed for migratory bird sustainability. You can also reach us by phone at (416) 366-3527.

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