By Julia Schimmelpenningh
Thanks to the pioneering work of dedicated scientists, ornithology, wildlife associations, and the glass industry, the future is looking brighter for the billions of birds which collide with windows each year. While still in its infancy, the science of bird-safe glazing is emerging with creative new ideas and changing the way birds see and react to building glass. Similar to the evolution in hurricane-resistant glazing which began several decades ago, the road to developing adequate bird-friendly codes, local ordinances, and glass testing is evolving. For specifiers tasked with selecting bird-friendly glazing, this article provides an overview of current glass testing options and other information to help in designing a beautiful yet bird-friendly building.
How big is the problem?
Birds are essential to the ecosystem. They consume vast quantities of insects and control rodent populations, further reducing damage to crops and forests and limiting the transmission of diseases such as the West Nile virus (WNV), dengue fever, and malaria. Birds also regenerate habitats by pollinating plants and dispersing seeds.
With the increase in glass as a design medium, bird collisions into architectural fixtures and buildings have also increased, and awareness of this has become a chief driver for bird-friendly guidelines and regulations. Technical improvements and performance capabilities have made glass more accessible and desirable for architects; however, its transmissive and reflective nature, although beautiful to humans, can confuse birds. Birds cannot distinguish the presence of glass in architecture, so they attempt to fly through it. If the glass is reflective, it can present an oasis effect by somewhat mirroring the surrounding vegetation and environment, drawing birds into a reflection of the world around them which is not real.
Glass on lower levels closest to the ground and adjacent to “green” patios and balconies can reflect vegetation or landscapes, posing just as much risk for bird strikes as upper-level glass reflecting clear skies or providing seemingly pass-through corridors for flying. Birds attempt to reach habitats, open spaces, or other attractive features visible through or on glass surfaces.
Birds use their eyesight to orient themselves, but most birds have eyes on the sides of their heads. This allows them to see sideways at a wide angle, giving them a view of any approaching enemies or mates from all directions. The disadvantage, however, is their spatial vision is severely limited, and they have difficulty recognizing obstacles in fast flight. Birds in flight may only see the landscape behind the pane of glass and fly against it unchecked.