OAKLAND, Calif. -- Birds and buildings can be a fatal combination. The American Bird Conservancy cites studies estimating that hundreds of millions of birds die each year as a result of colliding with walls and windows.
But a movement to make skies a little friendlier is taking flight; some cities and other governments across the country are adopting bird-safety building guidelines on a mandatory or voluntary basis.
One of the latest cities to incorporate bird safety into housing regulations is Oakland, where officials this year revised guidelines originally approved in 2008 to make them more effective. Neighboring San Francisco adopted bird-friendly requirements in 2011, working with the American Bird Conservancy and Golden Gate Audubon Society, and the state of Minnesota also has bird-friendly design requirements, modeled after a LEED (Leadership in Engineering and Environmental Design) bird collision reduction program. The Minnesota requirements are part of a sustainability program that applies to projects with any state funding.
The state of California includes voluntary bird-friendly measures as an appendix to its green building code, known as CALgreen.
What exactly do bird-safety regulations entail?
A big issue is glass. Just as many a human has taken a nasty smack walking into a clear glass door, birds often come to grief when confronted with transparent picture windows or glass-sided buildings. Unlike humans, birds don't pick up on architectural cues; they don't see a window frame and realize it implies a window.
But that doesn't mean that bird-friendly buildings have to be "windowless warehouses," says Christine Sheppard, bird collisions campaign manager at the American Bird Conservancy.
Glazing treatments, such as making glass opaque or using etching to make it more noticeable, can deter collisions. And research is being conducted into the efficacy of glass patterned with vertical or horizontal lines.
"We've actually done quite a bit of this sort of testing, building on the work of Dr. Dan Klem at Muhlenberg College in Pennsylvania and Martin Roessler in Austria," says Sheppard. "We know that there are highly effective patterns that cover less than 10 percent of the glass surface. We know the basic dimensions of spaces birds won't try to fly through, but we still need to determine the minimum size of the elements that create the spaces -- lines can be broken up, patterns can be made of dots, lines don't have to be straight, etc."
From a design perspective, incorporating bird safety can be challenging, says Ryan Hughes, project manager at Lundberg Design in San Francisco. Clients want views, especially in a city like San Francisco blessed with hills overlooking a big, blue bay. And glass provides those views, whether that's a floor-to-ceiling wall or a barrier around the edge of a terrace.
Still, new glass products, including the type with minimal lines, can be part of an acceptable compromise. And sometimes, what's good for humans is also good for birds: Lundberg designed glass bus shelters for the city of San Francisco that included a subtle pattern on the glass -- called SF fog because it is denser at the bottom and dissipates at the top -- to keep people from walking into the walls. Hughes said he later heard from bird safety officials that the pattern is effective at warding off birds, too.
The problem of bird collision isn't limited to public structures or skyscrapers.
"The estimate is that pretty much any home probably kills between one and 10 birds a year," says Sheppard, author of the bird conservancy's "Bird-Friendly Design." (That figure is based on work by Klem, as well as by Scott Loss at the Smithsonian Conservation Biology Institute.)
Making your home a more bird-friendly place can be as simple as sticking Post-it notes on the windows during high danger times, such as spring or fall bird migrations. Other relatively simple options that benefit birds and humans are window screens or shutters.
Oakland's bird safety measures are part of the building permit process and apply to all construction projects that include glass as part of a building's exterior. They also apply to projects that meet one of several criteria, including being next to places where birds are likely to congregate, such as a large body of water or a recreation area.
Scott Miller, Oakland's zoning manager, says he hasn't heard many complaints from developers. The rules, he says, are "really quite reasonable. They're not restricting development in such a way that would be objectionable. They're just providing measures that make buildings friendlier to birds."
Measures include bird-friendly glazing treatments; avoiding the use of mirrors in landscape design; and avoiding putting things that attract birds near glass. Other bird-friendly practices include turning off more lights at night, since lit windows can attract night-flying birds. Minimum-intensity white strobe lighting with a three-second flash is better than solid red or rotating lights, which attract birds.
Taking steps to keep birds safe is more than just kindness, says Sheppard. Birds have an ecological impact dispersing seeds and eating harmful insects.
"People should care about birds," says Sheppard, "because we need birds."