Bird-Friendly Building or Avian Abattoir?

10/01/2014 | By Janelle Penny

Sustainable facilities may be deadly for birds

For your sustainability practices to truly take flight, it’s not enough to green the inside of your building. Your facility impacts the rest of the site surrounding it – and it may be dangerous to local wildlife.

Glass buildings are beautiful and provide occupants with much-needed daylight, but to birds, they frequently appear as uninterrupted sky. Colliding with glass is the biggest known killer of birds in the United States and is responsible for hundreds of millions of deaths every year, according to the American Bird Conservancy. In addition to the environmental impact, the sight and sound of birds slamming into windows are distressing for the occupants who witness the phenomenon.

Green practices can’t stop at your doorstep. Read on to discover how to make your building bird-friendly.

Is Your Building Dangerous for Birds?
Migratory songbirds such as sparrows, thrushes, and warblers are typically the most vulnerable, especially during migration periods in spring and fall, explains Christine Sheppard, bird collision campaign manager for the American Bird Conservancy. Birds typically feed on insects, some of which can transmit disease or damage trees if there are fewer birds to control their population.

3 Tactics That Don’t Work

1) Small Frits
Examine potential frit patterns from a distance. How well can you make out the dots? If you have a hard time distinguishing between them, it will be even harder for birds, who may perceive the dots as small clouds on the horizon. Ideal frits are prominent and arranged into patterns, such as stripes or larger shapes, to drive home the point that your window is not sky.

2) Indoor Patterns
Films or tapes attached to the inside of your glass may not ameliorate the whole problem because the outside of the windows is still reflective. Depending on the angle, birds may not see your film at all thanks to the reflection on the outside. The best films and tapes attach to the outside to help break up the glare.

3) Silhouettes
Giant patterns of hawks and owls (such as the one at right) are popular choices because many people believe smaller songbirds will fear the predators, but this is rarely the case, Sheppard notes: “Birds don’t recognize silhouettes as dangerous. They just recognize it as something they can fly around.” If you’re sold on window films, Bates recommends working with an architect to design a film that mimics frit patterns.

Unfortunately, some of the same features commonly used to create sustainable buildings that are healthy for occupants can be deadly to birds – namely, the increasingly popular expanses of glass. Glass presents a two-pronged problem: depending on how reflective it is, it can appear as either a transparent view into your indoor plantings or as a reflection of the sky and outside vegetation. In both cases, birds simply perceive it as space they can fly through.

Nearby vegetation exacerbates the problem. Birds are drawn in when they look for places to roost or feed, but they become confused when they see the same trees or plantings reflected by glass and may collide with the window attempting to forage in the plants they think they’re seeing. Try taking a look around your property to find potential trouble spots.

“Look at all of the types of habitat provision that might be happening,” says Roderick Bates, an associate and LEED AP with KieranTimberlake, a Philadelphia-based architecture, research, and planning firm. “Do you have plantings that provide berries and are fruiting during certain times of year? Do you have water features? How big are your ledges or parapets?”

Light is also a powerful draw for birds, especially if your area is foggy or overcast at night, when migration typically takes place. Intense light projected into the sky refracts and disorients the birds, who can literally become trapped in the skyward beams. Buildings that are lit all night also contribute to the phenomenon.

“They’re drawn to the beams of light like moths,” explains Deborah Laurel, principal for Prendergast Laurel Architects. “In places like New York where a lot of lights shine all night, birds are attracted and get exhausted. They end up on the ground or find a tree to perch on for a while. When dawn arrives, they’re in the middle of a glass canyon, which is disorienting. They forage for some sustenance to keep going, but when it’s bright and sunny, the reflections of trees and the sky are more intense on any kind of glass surface and they’re prone to be caught on the glass when they try to navigate.”

Try Temporary Solutions
First, narrow down which areas of glass tend to attract the most bird strikes. More than likely, you won’t have to find fixes for every window – one face or even just a few panes could be responsible, Laurel says. Start with complaints and anecdotal evidence from occupants to narrow down which areas of your building are causing the most casualties.

Next, look at your budget. You probably can’t replace the glass in the biggest problem areas – at least, not right away – so you may need to turn to short-term solutions to cut down on bird strikes while you figure out how to tackle the problem in the long term.

Tempera paint: This art class mainstay can buy you some time until you’re able to identify something more permanent. The idea is to break up the large swaths of clear glass so birds can see that there’s an obstruction in their flight path. Try painting squiggles, strips, or dots – just make sure they’re about 4 inches apart vertically, Laurel recommends.

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