Bird-Friendly Building Design Bird-Friendly Building Design

Awnings and OverhangsOverhangs have been said to reduce collisions, however,they do not eliminate reflections, and only block glass fromthe view of birds flying above. They are thus of limited effectivenessas a general strategy.Overhangs block viewing of glass from some angles, but do notnecessarily eliminate reflections. Photo: Christine Sheppard, ABCReflections in this angled façade can be seen clearly over a longdistance, and birds can approach the glass from any angle. Photo:Christine Sheppard, ABCUV Patterned GlassBirds can see into the ultraviolet (UV) spectrum of light,a range largely invisible to humans (see page 36). UVreflectiveand/or absorbing patterns (transparent to humansbut visible to birds) are frequently suggested as the optimalsolution for many bird collision problems. Progress in thesearch for bird-friendly UV glass has been slow, however,due to the inherent technical complexities, and because,in the absence of widespread legislation mandating birdfriendlyglass, only a few glass companies recognize this asa market opportunity. Research indicates that UV patternsneed strong contrast to be effective.Angled GlassIn a study (Klem et al., 2004) comparing bird collisionswith vertical panes of glass to those tilted 20 degrees or40 degrees, the angled glass resulted in less mortality. Forthis reason, it has been suggested that angled glass shouldbe incorporated into buildings as a bird-friendly feature.While angled glass may be useful in special circumstances,the birds in the study were flying parallel to the groundfrom nearby feeders. In most situations, however, birdsapproach glass from many angles, and can see glass frommany perspectives. Angled glass is not recommended asappropriate or useful strategy. The New York Times printingplant, pictured opposite, clearly illustrates this point. Theangled glass curtain wall shows clear reflections of nearbyvegetation, visible from a long distance away.20 Bird-Friendly Building DesignDeeply recessed windows, such as these on Stephen Holl’s Simmons Hall at MIT, canblock viewing of glass from most angles. Photo: Dan Hill