In the U.S., as many as one billion birds die each year from accidentally colliding into glass windows of buildings.
We can’t get our head around this number—one billion—and yet that number apparently is already a conservative estimate.
The Aqua Tower in Chicago: Poster building for bird-friendly architecture
This is one of the tricky paradoxes of green buildings—their reliance on glass that’s both daylight-inviting and heat-insulating—the very features which make them eco-friendly—in turn poses risk to birds who fly directly into the glass.
That’s not the birds’ fault. Migratory birds are exceptional navigators of the skies, but are practically helpless when confronted with glass. The birds mistake the glass reflections for the open skies, or else are lured by the trees and greenery reflected onto it. These clueless birds hurtle straight into the glass—they get stunned, fall to their death, or become too impaired to continue the rest of their journey.
Since birds aren’t likely to make the evolutionary jump from clueless to discerning any time soon, it’s up to the green builders to make the necessary adjustments.
Bird-Friendly Buildings According to LEED
Bird fatalities from building collisions are even greater than from wind turbines.
(Image from greensource.construction.com)
Two years ago, the USGBC came out with a Bird Collision Deterrence credit, initially tested by the program’s Pilot Credit Library. This bird-friendly move by the USGBC was inspired by the campaign of the American Bird Conservancy and the Bird-Safe Glass Foundation who have rated collisions with glass windows one of the leading causes of death, alongside cat predation, wind turbines, and oil spills.
Under the Bird Collision Deterrence guidelines, buildings must comply with one façade requirement, one interior light requirement and one exterior light requirement, as well as develop a monitoring program.
The goal of the façade requirement is to make buildings “become visible as a physical barrier and eliminate conditions that create confusing reflections to birds.” The sleek glass skins that are currently trendy among builders should ideally incorporate “visual noise”—colored, textured, opaque, patterned, coated, and fritted glass as opposed to clear, transparent glass. For a low-tech option, the simple use of a decals on windows can go a long way towards preventing bird collisions.
As for lighting, occupants of buildings should turn off the lights at night when the room isn’t in use (something each one of us can, no doubt, do.) Additionally, the building should have automatic lighting controls, or at least an “appropriate nighttime personnel” dedicated to turning the lights off when not in use.
For the exterior lighting requirements, the goal is to “shield all exterior fixtures such that the installed fixture does not directly emit any light at a vertical angle more than 90 degrees from straight down.
Bird-Friendly Buildings, a Win-Win Scenario
Bird collisions aren’t as visually dramatic as fatalities because of oil spills, which is why the former is often underreported by news media. With bird collisions, there’s none of that pitiful image of a blackened, oil-drenched avian creature struggling on the shore. There’s only the immediate aftermath—the fallen bird on the ground, quiet, still, and dead.
Which is all the more reason green builders should look into this sad phenomenon. As cities steadily grow and encroach the spaces previously enjoyed by birds, we need to make sure our feathered friends don’t become the victims of our progress. It’s only been two years since LEED started giving credits to bird-friendly buildings, and even then it’s only a mere one point. That shouldn’t discourage green builders though.
One billion is certainly hard to digest, but in our own little way we can all make a difference to lower that number.
