Design for Bird Safe Buildings by Bishoy Takla

CUNY

I CCNY I Ms. Sustainability Spring 2011

Sustainable Aquatic, Terrestrial and Atmospheric Systems

Design for Bird Safe Buildings

David Salmon I Bishoy Takla

Contents Environmental Issue.................................................................................................................................. 2 Ecological Concepts.................................................................................................................................. 3 Daily Life .................................................................................................................................................. 5 Bird Vision and Perception ....................................................................................................................... 6 The Urban Landscape ............................................................................................................................... 8 Angled Glass Facades ............................................................................................................................. 11 Birds Can‘t See Transparent Glass ......................................................................................................... 13 How Do Birds See?................................................................................................................................. 13 Spiders‘ Web Effect ................................................................................................................................ 14 Case Studies ............................................................................................................................................ 17 The Dark Side of Light ........................................................................................................................... 19 Solution for Light Pollution .................................................................................................................... 21 Conclusion .............................................................................................................................................. 22 References ............................................................................................................................................... 23

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Environmental Issue Man has coexisted with birds through all his existence; they predate us in evolutionary time, and have extraordinary ecologyâ&#x20AC;&#x201D;including migrations that can span many thousands of miles. Their evolution has a global reach that is unique in the animal kingdom. Humans have enjoyed their flight, colors, songs, and birds have been prominent in human cultural history. People have benefitted from how birds fit into the biotic community, controlling insect populations, for example. As civilization has developed, however, this coexistence has interrupted bird life in various ways, from hunting, chemical poisoning and habitat destruction, to disruptive habitat creation. Many of the neotropical songbirds we enjoy in North America, winter in Central and South American forests. Agricultural practice in the tropics and logging in the Canadian Boreal forest has resulted in degradation of both winter and summer habitat, and is the greatest cause of decline of many species. Similarly, man-made structures have added ecological stressors by placing structures within the bird environment.

Copied from New York City Audubon Bird Safe Building Guidelines

Collisions with man-made structuresâ&#x20AC;&#x201D;houses, urban buildings, turbines, tower structures, power lines, vehiclesâ&#x20AC;&#x201D;are second only to habitat loss as cause of bird mortality. It is estimated that as many as one billion birds are killed annually in the United States alone by anthropogenic causes. Of the total, the USDA Forest Service estimates 58% to be from collisions with buildings,

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compared to 14% for power lines, 11% for cats, and less than 1% from turbines. 1 Other sources estimate the number of birds killed in collisions with buildings to be higher, at least a billion annually in the US alone. Noted Ornithologist Daniel Klem Jr., comparing these numbers to those of a well known and publicized disaster, has said that accepting even the lowest of the estimates of 100 million per year, â&#x20AC;&#x2022;we would need a comparable 333 Exxon Valdez oil spills each year to match the losses.â&#x20AC;&#x2013; 2 This paper will look specifically at the effect of buildings on bird mortality and measures that can be taken to minimize that impact.

Ecological Concepts Birds have evolved to fit into the environment on a global scale. Flight allowed birds to follow food sources over thousands of miles. A majority of North American birds are migratory, some migrating from the tropical forests of the Caribbean, South or Central America to our area and further north, to the Boreal forest of Canada. New York sits directly in the path of the Eastern Flywayâ&#x20AC;&#x201D;a major migratory path in both spring and fall. Chicago, Detroit and Toronto are in the path of the Mississippi Valley/Great Lakes Flyway that traverses the center of the continent. These cities and their surroundings have disrupted the migratory routes. We have fragmented habitat, and built structures that birds do not recognize as obstructions to be avoided and too often kill them, within their ecological habitat. The desire to have satellite communities away from the urban center, closer to nature, is accelerating the modern decline of our larger biotic communities, including birds and other living beings.

Wood Thrush with Young. Compliments Birds and Blooms

Erickson, W.P, G.D. Johnson, D.P. Young. 2005. A Summary and Comparison of Bird Mortality from Anthropogenic Causes with an Emphasis on Collisions. USDA Forest Service Gen. Tech. Rep. PSW-GTR-191. 2

Klem, D., Jr. 2009. Avian Mortality at Windows: The Second Largest Human Source of Bird Mortality on Earth. Proceedings of the Fourth International Partners in Flight Conference: Tundra to Tropics 244251. Page 3 of 23

Songbird populations are on the decline throughout the Americas. Kirtlandâ&#x20AC;&#x2DC;s Warblers, an endangered species recovering from near extinction, are on the Mississippi Valley Flyway and have been found dead from collisions with buildings. 3 Many Neotropical migrants that are either threatened or listed for special consideration, primarily due to habitat destruction, appear on the lists of primary species mortality due to collisions with buildings in the Eastern Flyway. These include Ovenbird, Blackpoll Warbler, Northern Parula, Wood Thrush; Black-throated Green, Canada, Bay-breasted and Prairie Warblers; Scarlet Tanager. It appears that the largest number of urban bird/building collisions occur during the spring and fall migrations. 4 5 The last halfcentury has been an era of unprecedented growth and building in the eastern urban corridor. The architectural landscape of our cities has largely taken shape in that time, and the suburban surroundings have grown exponentially with satellite centers, spreading into what had once been more pristine habitat for both migrants and birds that live and breed in our area. Although just beginning to be documented and known, it is likely that the change in man-made structures in the major flyways has been a significant factor in the decline of certain bird species together with summer and winter habitat destruction.

New York City Audubon Bird Safe Building Guidelines 3

Klem, D., Jr. 1990. Collisions Between Birds and Windows: Mortality and Prevention. Journal of Field Ornithology, 61(1):120-128. 4 Gelb, Y., N. Delcretaz. 2009. Windows and Vegetation: Primary Factors in Manhattan Bird Collisions. Northeastern Naturalist. 5 Cotton, K., M. Fry, S. Holmer, A. King, D. Schroeder, G. Shire. 2009. Saving Migratory Birds for Future Generations: The Success of the Neotropical Migratory Bird Conservation Act. American Bird Conservancy. Page 4 of 23

Birds often do not ―see‖ our buildings as obstructions and fly into them at speeds that cause fatal head trauma. Clear glass or plastic are essentially invisible to birds. 6 Man has disrupted bird ecology. In a very short ecological time, birds have had major new obstacles constructed in their environment that they did not evolve to recognize. The effect has been tragic and is only now beginning to be generally understood as an issue to be addressed. Disruption of bird ecology could affect other change. For instance, as budworms become more prevalent and threaten the Boreal forests, bird populations that might help control the insects, are declining. As the Boreal declines, a major world carbon sink is threatened. As the forest dies, stored carbon is also released, increasing global CO2 levels and accelerating global warming. Loss of winter habitat will further stress bird populations. What the succession ecology will be is unknown, but the effects are potentially global in reach.

Daily Life Architects and their clients have preferred the modern glass curtain wall façade for decades. Landscaping has also become an increasingly important aspect of building design in the more recent ―green building‖ development. The research data would support extreme caution in designing buildings in this model to avoid high bird casualties. Northern climates have also popularized the interior ―Winter Garden,‖ certainly pleasant for people, but without a visual separation from the outdoors, fatal to birds. Architects need to be educated as to the hazards and ways of mitigating danger to birds, and more research needs to be done to create new materials for the architectural palette. As demand for materials increases, the manufacturing sector will supply them. The recent design and manufacturing revolution in response to the USGBC LEED Certification program is solid evidence of that. The new LEED credit for Bird Friendly Design will help to educate more architects to this issue, and may in time even make for renovations to older buildings that are recognized hazards. It is interesting to note that if a person even unintentionally killed a North American songbird, he would be in violation of the Migratory Bird Treaty Act of 1918 and subject to legal action; yet killing millions through buildings we construct goes unchallenged. One scientist, Daniel Klem, Jr., has called for this treaty to be used to force changes to buildings that have proven to be especially fatal to birds.7

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Photograph Compliments Audubon Greenwich

Birding is a popular avocation in the US and worldwide. Every year fewer birds return in the spring migration. On International Migratory Bird Day last Saturday, May 14, David Salmon went on an annual Audubon IMBD walk in Greenwich, CT. Sitting later with two persons who have led walks there for the last 30 and 40 years respectively, each lamented the sharp decline in numbers of birds from when they first began. Anyone who birds these days with persons who have for decades hears the same account, which statistics confirm. The decline in birds will result in less birding related tourism, which will hurt the local economies of the places like Cape May, NJ, for instance, less sales of sports optics and other gear, and less connection to and understanding of nature at a time when the exact opposite is needed. Already too many people view birds as pretty or somewhat interesting, without understanding their amazing lives or their importance to the biotic communities they inhabit. Birds are the original pest managers, and they spread seeds, distributing life. The following sections will go into detail regarding research that has been conducted on birds and their relation to buildingsâ&#x20AC;&#x201D;both the dangers and what can be done to mitigate them.

Bird Vision and Perception Birds and human see differently. Until recently the differences have not been recognized in terms of building design. A recent article by British ornithologist Graham R. Martin in the periodical Ibis, reported on the physiological understanding of bird vision as well as possible cognitive processes that can help to explain the threat man made structures present to birds. 8 8

Martin, G.R. 2011. Understanding bird collisions with man-made objects: a sensory ecology approach. IBIS(2011), 153, 239-254. Page 6 of 23

Unlike humans, who have eyes placed frontally and separated sufficiently to allow binocular vision and depth perception, bird eyes are generally placed high on the sides of the head and very close together. Birds evolved to see in a narrow field, laterally, also stretching up and back—the primary direction of predators in flight. Birds have limited need to look in front of them for obstructions, as the skies they fly in, above the treetops, do not present threats in the forward direction. Their precise binocular depth perception is generally limited to the distance to the end of their bill or feet ―towards objects at close range, and not for the control of locomotion towards more remote targets.‖ This precise visual range is primarily for eating and caring for young. Martin writes that bird vision appears to emphasize the direction of objects and time to contact. Optic flow-fields play a vital part in both aspects, and are related to many tasks people do, ―such as driving, cycling, running, jumping and ball catching: tasks in which the observer has to adjust speed of approach to achieve accurate timing of arrival at a given point.‖ Optic flow-field information is not highly detailed, but low resolution. ―In essence, birds probably see the world ‗around them‘ and they move ‗through‘ it.‖ He adds that birds have no ―prior‖ knowledge/experience with the human built environment, and generally expect that above the treetops, the environment they fly through will be free of obstruction.

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Another significant difference between human and bird vision is color perception. Birds evolved to see light in the ultraviolet and near UV range. They also are able to differentiate color nuances to a much higher degree. The extended range and higher discrimination of color vision appears to be primarily for food location and perception of feather coloration, both associated with attraction: feather color with sexual attraction. One source has noted that spider webs, which reflect UV light, provide an example of a natural visual avoidance cue. Finally, and crucially important, is that birds do not have a broad range of flight speeds. They do not generally fly slow or fast as they wish. They have a narrow range of speed dependent on wing loading physiology. When a bird collides with a building, it is in that natural range of speed and fast enough for fatal trauma, even if taking off from a fairly close distance. Brain trauma from collisions is the primary cause of death.

The Urban Landscape The greatest threats to birds within the urban landscape are the windowed facades of our buildings, especially when they reflect or reveal behind an attractive, familiar landscape. It appears that glass of any size is equally threatening to birds—from curtain wall and large plate glass to smaller paned residential windows. 9Glass can reflect foliage of adjacent trees and appear as an extension of the natural landscape. Interior landscaping seen through a transparent wall appears as an extension of the exterior. Glass can reflect the sky and be invisible as a solid surface to birds. Yigal Gelb and Nicole Delacretaz analyzed data collected over an eleven-year period by NYC Audubon‘s Project Safe Flight of bird collisions at various Manhattan building sites. Their findings were detailed in the paper published in Northeastern Naturalist in 2009. 10They sought to test two hypotheses: ― (a) that the frequency of collisions is highest along those portions of the exterior glass surface that reflect outside vegetation…or display indoor vegetation…and consequently, (b) that most of these collisions occur during the daytime hours when birds are feeding.‖ The survey data supported the hypotheses and also showed that bird/building collisions peaked in the fall and spring migrations.

Klem, D., Jr., C.R. Farmer, N. Delacretaz, Y. Gelb, P.G. Saenger. 2009. Architectural and Landscape Risk Factors Associated with Bird-Glass Collisions in an Urban Environment. The Wilson Journal of Ornithology 121(1):126-134. 10

Gelb, Y., N. Delcretaz. 2009. Windows and Vegetation: Primary Factors in Manhattan Bird Collisions. Northeastern Naturalist.

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Two high collision areas surveyed were the World Financial Center and the Morgan Mail Building in Chelsea. The Winter Garden at the WFC, with its extensive clear glazing and interior landscaping, was the highest collision site for that complex, with 426 birds collected. For the complex as a whole, 1,094 birds were collected over the period.

Morgan Mail Building

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By far the highest individual building collision site was the Morgan Mail Facility with 904 birds collected. All-day surveys were conducted in one three-day study in 2005, beginning at 6:45 and ending at 17:30, with the earliest collection period accounting for overnight collisions. It separately covered the eastern and western halves of the south faรงade, which faces a park of 1.42 hectares. The eastern portion is directly opposite a row of large street trees, reaching in height to the top of the 6-story building. The western portion faces an area of the park with ball fields and far fewer trees. The first 2 stories of the building were windowless concrete, and the upper 4stories covered entirely in reflective glass panels.

Diagram of the Morgan Mail Center Showing Faรงade Sections

Strike frequency was highest at the landscape-reflecting eastern side of the faรงade, with 73% of the birds collected there, vs. 27% for the western half. The strike distribution over the two halves of the faรงade was proportionate to the number of tall trees opposite. Additionally, 82% of the strikes occurred during the daytime feeding hours. The majority of the birds killed were migrant passerines in the warbler, sparrow and thrush families. Overall data supported the Morgan Mail Building findings. All the top-ten sites included large windows, all with surrounding vegetation, with the WTC and Winter Garden having extensive interior vegetation behind glass facades. The majority of time-indexed strikes were in the daylight hours, and the fact that the highest incidents of strikes were glass facades incorporating landscaping supported the daytime hypothesis. Additionally four of the top ten sites were low

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rise buildings less than 40 meters tall, the height of an 8-10 story building, which has tremendous implications for expanding suburban centers and office parks throughout the area.

Angled Glass Facades Daniel Klem, Jr., Sarkis Acopian Professor of Ornithology and Conservation Biology at Muhlenberg College in Allentown, PA, has been studying bird collisions with man-made structures for over two decades, and his research, writings and lectures have been instrumental in current developments in architectural design and materials to prevent fatal bird strikes. One research project reported in the Wilson Bulletin in 2004 studied the effects of angled glass and feeder placement relative to the glass. 11 The results have important implications for building design. The study tested the differences between clear and tinted glass, mounted vertically, and angled down 20° and 40°. Additionally, for each configuration, feeder stations were placed alternately across from the glass at distances of 1, 5 and 10 meters from the glass surface. The glass panels measured 1.4m wide by 1.2m high and were mounted in wood frames. They were placed within a field, and separated from each other by distances that might be common in a residential setting, from 15 to 43 meters. Wire trays were placed at the bottom of the glass to catch birds that collided with the panels, and keep them from predation. Each of the stations was tested with clear and tinted glass. The greatest number of strikes occurred with the glass in the vertical position, 57%, followed by 28% at the 20° position, and 15% at 40°. Additionally, the percentage of fatalities recorded at the 40° angle was significantly lower, probably because the angle of the glass tended to deflect collisions and lessen the impact. The feeder placement study showed that the closer the feeder placement, the fewer strikes and fewer fatalities per strike. The one-meter placement resulted in the lowest number of strikes at 24%, with none fatal. 28% of the strikes occurred from the 5-meter distance, with 33% of the total fatalities. From 10 meters, 48% of the strikes occurred, and 67% of the total fatalities. At 5 meters, 59% of the strikes were fatal, and at 10 meters 69% were fatal.

Klem, D., Jr., D.C. Keck, K.L. Marty, A.J. Miller Ball, E.E. Nichiu, C.T. Platt. 2004. Effects of Window Angling, Feeder Placement, and Scavengers on Avian Mortality at Plate Glass. Wilson Bulletin, 116(1), 69-73 Page 11 of 23

In this experiment, the number of strikes to the tinted panels was about half that of the clear panels overall with no fatalities. However, they attributed this result to lesser quality, salvaged glass that had poor reflectivity. Dr. Klem notes that a previous experiment testing clear and tinted reflective glass conducted in 1989 found both to be equally lethal to birds, noting that further study is needed to test the differences, if any.

The implications of the study are important for both residential and urban/commercial settings. First, where feeders are located, they should be placed within one meter of any glass surface. This same rule seems to best apply for landscaping around buildings. Trees placed within a Page 12 of 23

meter of a glass façade will result in fewer strikes and the close distance does not allow birds to get sufficient velocity to cause fatal trauma if they do collide with the glass. Angling glass down by 40° definitely resulted in both fewer strikes and fewer fatalities per strike. Dr. Klem recommends that architects designing glass facades consider angling the façade, especially at the lower stories where landscaping may be reflected.

Birds Can‘t See Transparent Glass There are billions of square feet of clear glass surfaces in US which contribute to energy efficiency, effective day-lighting and aesthetic views. However, most of these windows present a big hazard to birds, both tall buildings as well as large glass surfaces can be a problem. Glass surfaces are the largest unintended man-related cause of birds‘ fatalities, an average building kills from 1 to 10 birds per year. Indications from known collisions experiments show conclusively that birds are not able to distinguish glass as a possibly deadly obstacle; glass is invisible to them. No birds seem to be resistant to this danger, around 25% (225/917) of all North American bird species have been documented as killed or injured by collisions 12. The remaining species that were not documented as window-kills are those that typically do not interact with human society, for example water birds and terrestrial species occupying uninhabited desert and forest. But what really makes all those birds collide into glass? From human point of view, it seems very odd that birds fly into glass. However as Graham Martin, Professor of Avian Sensory Science at Birmingham University says in a press release, "Birds live in a different visual world to humans‖13. The conflict exists when we look at the problem from our perspective, but once we understood how birds see, we can easily draw a conclusion to this great hazard.

How Do Birds See? In the early 1970s scientists14 proved that birds can see UV lights, that means the retina of bird‘s eye contain four cone types, each is sensitive to a specific wave length (i.e. red, blue , green and ultraviolet) while humans have only three cone types (red, blue and green). Birds have photo-pigments with sensitivities at four or five peak wavelengths, making them true tetrachromats, or perhaps even pentachromats. In other words birds can see more than we can. Birds‘ eyes are sensitive to wavelengths from 320 to 700 nm, whereas the human visual spectrum is from 400 to 700. In fact scientists suggest that bird eyes are five times as sensitive to UV light than visual light. However, they do not understand glass as a barrier to be avoided nor understand reflection. Thus, they fly head-on into windows usually in high speed. The main reason is that they look at small focused portion of the glass without recognize the overall silhouette of the building. Birds use their UV vision in their daily activities for example for 12 13

http://www.flap.org/new/ccourse.pdf http://news.bioscholar.com/2011/03/here%E2%80%99s-why-birds-collide-with-man-made-objects.html Huth and Burkhardt (1972), Wright (1972), and Diez (1972)

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orientation and navigation, for mating and social signaling and for determining the fruits on trees. Some fruits and berries are covered with waxy UV light reflector to advertise fruits to potential seed dispersers.

Spiders‘ Web Effect We can easily find solution to birds‘ collision into glass by markings the glass with patterns that are visible to birds but invisible to human eyes. Since birds can see UV light and human cannot, we can mark our windows with material that reflect UV light in order to alert birds, while at the same time the glass will provide a transparent view for human eyes. Spiders use the same concept, enabling birds to avoid their webs. Spiders‘ web reflects UV light so that birds can avoid it. ―The UV-reflection of the spider‘s threads protects the web against the destruction by birds which can discern UV especially well‖15. Although normal glass slightly reflects UV light, it is not enough to warn birds because of the lack of contrast between UV reflector material adjacent to UV absorber frame. Making glass a UV reflector can be achieved by either adding a film on the exterior side or by spraying ‗bird-protection-spray‘ to add thin UV reflecting layer. But more effectively, the UV reflecting material could be applied to the internal sides of double- or triple-pane-glass through its manufacturing process; similar to what is being done with other e-coating layer for insulation and solar gain control. In such bird-friendly-glass the UV reflecting layer would be inside the glass away from the weather or cleaning impact. 16

However, an accurate solution for existing windows will have to keep the aesthetic appearance and the function of glass. This will require studies that consider visual modifications and an adequate level of bird protection. The ultimate solution to prevent bird collisions with existing windows is to entirely cover the transparent surfaces of glass so that birds can recognize those surfaces as space to be avoided. Complete exterior coverings disrupt the translucent or reflectivity of glass enough to direct flying birds away from the hazard zone. This solution is commercially available from http://www.lfdcollidescape.com. Also partly covering of windows, according to Dr. Daniel Klem‘s experiment17, is as useful as complete covering if patterns are separated by no more than 2 inches horizontally and 4 inches vertically, so that a bird believes that it can‘t fit between the space. Moreover, covering glass with netting or even insect screens prevents birds from colliding with the hard glass surface. This is an acceptable solution for small or medium size buildings; however it is cost prohibitive for large window sizes. Such a technique is commercially available from www.birdscreen.com. Dr. D. Klem did a very enlightening experiment 18 to compare different types of glass from birds‘ point of view, he used clear sheet of plastic, then added UV reflecting decals, then 15

http://www.windowcollisions.info/public/buer-regner_engl_2002.pdf http://www.lfdcollidescape.com/photos.html 17 http://www.savingbirds.org/windows.html 18 Preventing Bird–Window Collisions 16

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added UV reflecting grid pattern with different distance and finally used ceramic frit with a dot pattern, each placed in a large box designed for testing bird avoidance. The individual birds were released from a container at the narrow end and forced to choose between the left or right flight path to escape from the box. One pathway was always unobstructed in all experiments while the other one was obstructed by the type of glass being tested (1.2 m wide X 0.9 m high), from both path ways birds could see a view of wooded evergreen habitat. During the experiment, if a bird chose the obstacle side it was counted as a window strike but if it chose the open side it was recorded as an avoidance. Birds were protected from actually colliding with the glass. The tested objects were: (1) Clear plastic with a UV-absorbing component (2) Single translucent UV-reflecting maple leaf decal (3) Uniform covering of 12 UV-reflecting maple leaves decals, as in #2, placed 10 cm apart in vertical columns and 5 cm apart in horizontal rows (4) A single clear monofilament line attached to the quill of four colored (from top: red, blue, yellow, and green) contour feathers measuring 14.4â&#x20AC;&#x201C;19.6 cm long and separated by 33 cm (5) 0.32-cm thick vertically oriented 2.5-cm wide UV-absorbing plastic strips forming stripes separated by 10 cm (6) Vertically oriented 2.5-cm wide UV-absorbing strips forming stripes as in #5 but separated by 5 cm (7) Horizontality oriented 2.5-cm wide UV-absorbing strips forming stripes as in #5 but separated by 5 cm (8) Ceramic frit glass uniformly covered with a pattern of translucent-appearing dots 0.32-cm in diameter separated by 0.32 cm.

The experimentâ&#x20AC;&#x2DC;s result shown in the following table indicates: - The single UV reflecting leaf decal was ineffective - The UV reflecting leaf decal is effective when applied in sufficient number to give birds a feeling of barriers. Page 15 of 23

The usage of UV absorbing film produced weak reflectivity as low as 13% reflectance, while UV reflecting film produced UV reflecting signal with 80% reflectance19. The horizontal UV strips separated with 5 cm apart was more effective than the vertical orientation. Ceramic frit dots uniformly covers the glass resulted in the highest avoidance number

Combining all these techniques into a hybrid solution of UV-absorbing film, UV-reflecting film and grid pattern can increase bird avoidance. According to Dr. Klemâ&#x20AC;&#x2DC;s experiment birds were able to recognize and avoid glass covered with ceramic frits of a translucent dot pattern easier than recognize glass with 2.5 cm wide stripes forming vertical columns 2.5 cm apart.

Prevent Bird-Window Collision â&#x20AC;&#x201C; Daniel Klem Jr.

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Case Studies Birdsandbuildings.org classified this problem into three main hazards, and I will use the same categories to identify successful bird-friendly-buildings. 1- Glass is NOT Air in ITT student Center Sometime it is even hard for people to notice very clear glass however we understand glass and predict where it might be even if we couldnâ&#x20AC;&#x2DC;t clearly see it. In contrast birds donâ&#x20AC;&#x2DC;t understand the concept of glass and deal with it as air. The picture below is a bad example of glass that is deceiving to people as well. Architect Rem Koolhaas successfully presents glass as an object to be avoided at IIT Student Center, Chicago, IL. The building is a 10,690 square meter, one-story building, sheathed in metal and glass. All the exterior glass has a dot matrix pattern producing visual noise that birds can recognize and therefore avoid it.

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2- Window is NOT Tree in Minneapolis Central Library Since birds don‘t understand the concept of reflection, the reflection of a tree in glass appears to be a real tree from bird‘s point of view; therefore Pelli Architects placed trees very close to the building. In addition to providing shade, the close placement prevents incidents of fatal bird strike since birds do not have sufficient distance to gain full speed flight.20

3- Building is NOT Sky in IAC Offices Birds are entirely misled by the reflection of sky and clouds in windows and particularly glass curtain wall skyscraper. This hazard is determined by the sun angle in the sky, for most of the day building can be harmless until the sun hits it from a certain angle producing a clear mirror effect, In the picture below, the area above the red line appears to be sky from a bird‘s perspective and it would fly towards the glass as if it were free space. Because of its strategic location by the Hudson River, the IAC building was carefully designed by Frank Gerry to protect migrating birds, with exterior fritted glass of uniformly white dots to reduce the reflection and more clearly define the building‘s boundary.

Bird-Safe Building Guidelines

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The Dark Side of Light Local bird species living together with humans face a constant threat from tall buildings as well as large areas of clear glass. Dr. Klem proposed that some individuals rarely learn to avoid such threats through experience21. However, migrating birds face such hazards wherever they encounter lighted structures along their migratory flight path. Artificial light can have a tremendous impact on migrating birds that can lead to fatal disorientation. Every year about 50 million birds passing over urban cities in United States22, bright artificial lights attract them when they fly at night, especially in lower visibility weather conditions. The reason is unknown but the fact is well documented, and historically, people used lights to attract birds at night to catch them for food. Migratory birds use the sun location, earthâ&#x20AC;&#x2DC;s magnetic field and stars to find their ways to their final destination. But when there is heavy cloud cover or stars are obstructed by bad weather, artificial light attracts birds, pulling them off their migratory path. Artificial lights can trap migratory birds by bleaching their visual view, leading them to lose their sight of the horizon. Once birds are trapped into a light beam they keep flying in circles, unable to leave the light boundaries because they hesitate to fly from a well-lit area to a darker one23. As a result, they can die from exhaustion or from collisions with each other. We can have a better understanding of the hazard if we overlay a NASA image of human made light over birdsâ&#x20AC;&#x2DC; migratory routes map. It is very obvious that almost every migratory route is passing by an urban city where there will be a greater chance for birds to be trapped by light or collide with buildings.

http://aco.muhlenberg.edu/documents/WilsonBull1989.pdf http://www.flap.org/new/ccourse.pdf 23 Bird friendly design guidelines 22

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Bird Friendly Building (BFB), part of the Fatal Light Awareness Program (FLAP), did a study which lasted four years (1997-2001) on impacts of light pollution and bird collision by monitoring 16 buildings in downtown Toronto. The report illustrates that the number of deadly bird collisions as well as the number of birds trapped by light dramatically increase with increased light emissions. The experiment quantified light emission from the16 buildings by taking 8 to 10 digital photographs for each building at night during the migration seasons. Then a ratio of lit windows to total visible window was calculated, and a seasonal chart for each building was produced. The number of birds killed or found injured had a significant correlation to light emissions. The graphs below illustrate the relationship between both the number of birds found dead and birds found injured to light index.

Thanks to BFB, there has been a statistically significant reduction in light emission at the 16 buildings monitored between 1997 and 2001, because the tenants of the 16 monitored buildings saw the experiment as a â&#x20AC;&#x2022;greenâ&#x20AC;&#x2013; initiative having a positive environmental impact24, as well as having an economic benefit of reducing power consumption.

Effect of Light Reduction on Collision of Migratory Birds, BFB

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Solution for Light Pollution

The simple response to the hazard of night-time migratory bird mortality at lit buildings is to turn off the lights--especially after midnight when seasonal night migration flights occur. But in big cities, street lights might be needed after midnight for other reasons such as security. Therefore the solution is twofold; first, to design bird-friendly street lighting features and second, establish a lights-out program during migration months. The recommended design for exterior light features will reduce light focused upwards by attaching cutoff shields to streetlights to eliminate unneeded light spill on buildings that might attract migratory birds. We can also reduce internal lighting in buildings from midnight to dawn, by using task lighting and shades where buildings are occupied.

Because of the recent awareness of fatal bird collisions, some North American cities started a lights-out program during the migration period. Starting in September and lasting to December, New York City encourages tall building owners to reduce building light emission including exterior lighting, interior lighting on upper floors, and lobby and atrium lighting. FLAP has illustrated the danger birds usually face from bright lights, therefore other cities, such as Toronto and Chicago started a similar light-out program. About 100 downtown buildings now participate in Chicago.

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Besides saving bird lives, the program saves a reasonable amount of energy every year. NYC Audubon notes that, â&#x20AC;&#x2022;For a building with 2.5 million square feet of floor space, turning off the lights after midnight would conserve more than 750,000 kilowatts and save approximately $120,000 this fall.25â&#x20AC;&#x2013;

Conclusion As human culture has developed, man has affected the biome in many ways. One aspect is how man has affected birds, altering habitat that is finely tuned to evolutionary development. Science is just now understanding how the built environment has impacted birds almost as severely as direct habitat destruction. Fortunately persons who have feeling for birds and understand the importance they have to ecology, have worked to understand both how birds see and how man can coexistâ&#x20AC;&#x201D;support rather than harm them. Much progress has been made. Less than a decade ago, even the scientific community had to be convinced this was a serious ecological issue. Today the impacts and solutions are becoming mainstream. Architectural materials are available and being developed that can mitigate the impact buildings have had to birds. The recent enacted LEED credit for Bird Friendly Design will further this effort. As architects understand the issues and options, new buildings will present fewer risks. This is one specific issue, but it is representative of the understanding, and humility, that persons must have as they share this billions of years old globe of life called Earth, and the progress that is being made.

http://www.nycaudubon.org/projects/safeflight/lightsout_pressrelease.shtml

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References 1. Ibis (2011), 153, 239-254. Graham R. Martin, Understanding bird collisions with man-made objects: a sensory ecology approach. 2. Proceedings of the Fourth International Partners in Flight Conference: Tundra to Tropics 244251. Daniel Klem Jr., Avian Mortality at Windows: The Second Largest Human Source of Bird Mortality on Earth. 3. The Wilson Journal of Ornithology, 121(1):126-134, 2009. Daniel Klem Jr., Christopher J. Farmer, Nicole Delacretaz, Yigal Gelb, and Peter G. Saenger. Architectural and Landscape Risk Factors Associated with Bird-Glass Collisions in an Urban Environment. 4. The Wilson Journal of Ornithology, 121(2):314-321, 2009. Daniel Klem Jr. Preventing Bird-Window Collisions.

(2002)â&#x20AC;? by M

ďż˝Vogel und Umwelt 13:31 - 41 , corrected by Friedrich Buer and Rudolf Schmid (08/2003).

6. USDA Forest Service Gen. Tech. Rep. PSW-GTR-191. 2005. Wallace P. Erickson, Gregory D. Johnson, and David P. Young Jr. A Summary and Comparison of Bird Mortality from Anthropogenic Causes with an Emphasis on Collisions. 7. Wildlife Damage Management, Internet Center for Fatal Light Awareness Program (FLAP), University of Nebraska - Lincoln Year 1996. Lesley J. Evans Ogden. Collision Course: The Hazards of Lighted Structures and Windows to Migrating Birds 8. Northeastern Naturalist 16(303:455-470, 2009. Yigal Gelb and Nicole Delacretaz. Windoes and Vegetation: Primary Factors in Manhattan Bird Collisions. 9. New York City Audubon. Bird Safe Building Guidelines. 10. City of Toronto Green Development Standard. Bird Friendly Development Guidelines, 2007.

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