Best practices for preventing collisions

To reliably prevent collisions, both reflective and clear glass should feature an integrated, printed or applied pattern that meets the following criteria:

• Density: Maximum 5 x 5 cm (2 x 2 inch) spacing between pattern elements. Wider spacing does not deter smaller birds from colliding.
• Size: Pattern elements should be at least 6mm (1/4″ inch) wide.
• Exterior surface: Pattern must be on the outside of the glass. On the inside, it will not be visible enough and will thus fail to break up dangerous reflections.
• Contrast: Pattern must be visible in all light conditions.

Note: The pattern can be any colour that is visible; the red dots above are for illustrative purposes only.

The use of less glass, specific integrated structures and other techniques can be combined with patterned glass to make buildings safer for birds.

Please note that we DO NOT recommend UV-reflecting glass or other products that rely on birds detecting UV patterns. Many bird species cannot see UV light, and UV light levels are lowest during the times of day when the risk of collisions is highest.

Visit the following pages for more information on bird-safe products and design resources:

What is a bird-safe building?

Briefly, a building that minimizes the risk of bird collisions is one where:

• At least 90% of the material in the exposed façade from ground level to 16 m (the primary bird collision zone) has a threat score of 30 or less, derived from controlled experiments by the American Bird Conservancy.
• At least 60% of material in the exposed façade above the collision zone meets the above standard.
• All glass surrounding atria or courtyards meets the above standard.
• There are no “see through” passageways or corners.
• Outside lighting is appropriately shielded and directed to minimize attraction to night migrating or nocturnal birds.
• Interior lighting is turned off at night if not in use and designed to minimize light escaping through windows during night operation.
• Landscaping is designed without features known to increase collisions.
• Actual bird mortality is monitored and compensated for (for example, in the form of habitat preserved or created elsewhere, mortality from other sources reduced, etc.).

Source: American Bird Conservancy