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| Bird-friendly buildings in Chicago designed by Studio Gang Architects: the Aqua residential tower, above, and a family home, below left |
The Aqua high-rise resembles eroded cliffs, with organically shaped balconies flaring out irregularly from the underlying rectangular tower. To fence in the terrace, the designers convinced the developer to use fritted glass (etched with grey dots) and pickets spaced at 4in intervals, thereby preserving views while making the barrier visible to birds. It’s a marked contrast with the glass towers that birds have a tendency to slam into.
Next to habitat destruction, architectural glass is the leading man-made killer of birds. Windows in US and Canadian cities claim roughly 34m birds a year during autumn and spring migrations, according to a recent study published in the Wilson Journal of Ornithology. Worldwide, researchers estimate the annual total to be in the billions. And while city centres, many of which are located on migration routes, are an obvious focus, houses in the suburbs claim a much higher toll.
But although some designers and like-minded clients make birds a priority, doing so is voluntary. In the absence of mandates, conservation groups, a few cities that lie along major migratory flyways, and some people within the green building community are looking to raise awareness.
Chicago lies on a big migration route, so city officials, local architects and conservation groups have made bird safety an issue. New York City and Toronto have made similar efforts, including much-publicised lights-out programmes. Still, it’s rare for buildings to incorporate bird safety features.
Birds generally do not perceive conventional glass as a solid. Depending on the conditions and the type of glass, they might interpret reflections as continuous space or fail to notice transparent panes. However, they perceive ultraviolet light as a separate colour, whereas humans cannot see it with the naked eye.
UV-reflective glass can ward off birds but it is also expensive, as few companies manufacture architectural glass that is specifically bird-safe and there has not been much research on its performance.
Landscaping and indoor plants also play a crucial role. Too much greenery near reflective surfaces or visible through glass can draw birds. Experts advise screening plants, limiting their height and placing them so they won’t reflect off adjacent buildings.
The likelihood of bird strikes can also be reduced by cutting down on illumination at night when possible, avoiding light pollution by using fewer and more effective bulbs, and not directing beams skyward.
For new construction, a brise soleil (shade), windows angled between 20 and 40 degrees forward, and fritted glass can reduce solar heat gain and have the added benefit of creating the type of visual noise that reduces bird strikes. Existing buildings can be draped with netting.
Advocates unsuccessfully lobbied the US Green Building Council to establish bird-safe design as an explicit criterion of its Leadership in Energy and Environmental Design (LEED) rating system.
Although suburbs take a greater toll on birds than city centres and houses far outnumber other building types, Jeanne Gang of Studio Gang argues that architects should concentrate on larger buildings along flyways.
“People with single family houses can ameliorate the risks on an individual basis,” Gang says. “The big concern is commercial and large-scale, residential buildings on migratory flyways. Single family houses, although they do have glass, are easier to deal with. For example, you can put bird feeders closer to the house rather than further away, which reduces the speed of collisions when they take off.” She also advises pulling the shades at night, especially during migration season.
Experts say the most critical zone is the first two storeys of a building, though the upper floors also draw contact and some high-rises extend into migration flyways. At the busier lower levels, birds need more visual cues. This might mean limiting window size, plastering glass with decals (perhaps advertising or art), overlaying openings with mesh or grilles or installing solar blinds.
Bruce Fowle, senior partner at FXFowle Architects, says most clients lack awareness, sympathy or both. “If I say we can’t have clear glass and suggest fritted glass or louvers, nine out of 10 times there’s a snicker,” he says.
Hence the need to publicise the problem, according to Gang. “It’s very hard to argue for it when talking to clients or to argue for government regulation,” she says. “People need more information on the cause and effect relationships.”
Fowle says: “We need a zoning type of map [labelling flyways and habitat], so I would know when I buy land to build on within 200ft of a river that it’s a major flyway, and we know from research that it is likely to be a problem.”
Bird safety apparently does not rank high on the list of most homebuilders’ concerns. When contacted, the US National Association of Home Builders was unaware of any programmes or design strategies to reduce bird kills.
Architects need to be able to specify affordable bird-safe glass, says Gang. “There has to be a product available that will address it,” she says. “If governments mandated it, for example, it would be more effective.”
But manufacturers will not commit to large-scale production without a guaranteed market. So far, most advocates are relying on moral persuasion and a gradual approach to market transformation, rather than pushing to address the problem through building codes.
Glenn Phillips, of the Audubon Society, an environmental and conservation organisation, says: “At the moment, we’re really thinking about carrots and not sticks – a voluntary approach. Until we have a diverse array of solutions to the problem, it’s not viable to try to prohibit bird-unfriendly buildings. We aren’t there yet.”
