At least 90,000 birds are killed every year in New York City by colliding with glass in buildings as they migrate to and from their breeding grounds. Many fly at night and are disoriented by illuminated buildings and structures; bright light interferes with their natural navigational cues. To help mitigate this critical problem for birds, New York City Audubon is encouraging New Yorkers to participate in Lights Out New York. From September 1st to November 1st, midnight until dawn, they urge everyone to turn off the lights in city building to save birds and save energy.

Urban Green Council’s Rachel Schuder recently spoke with Dr. Susan Elbin, Director of Conservation and Science at New York City Audubon about Lights Out New York:

Rachel Schuder: Why should someone interested in green building care about this issue?  Is it a really a big problem?

Susan Elbin: Being a green building is not just about being resource efficient in terms of energy consumption and construction, although Lights Out New York certainly does curb energy use.  Being truly green is about taking a holistic approach to our environment, and part of that is conservation of wildlife.  When manmade structures impede the ability of migratory birds to safely pass through or over our city, it is our responsibility to correct the problem. Turning lights out is an easy solution that really does help.

And yes, the problem is a huge.  New York City Audubon’s data indicate that 90,000 birds are killed every year from colliding with glass—a number that we know is underestimated.

RS: How does turning off interior building lights at night help migrating birds?  Aren’t birds more likely to collide with a building they can’t see?

SE: Migratory birds traveling at night are drawn to lighted areas, a phenomenon known as the beacon effect. Combined light emissions from city buildings produce an urban glow, like you see in nighttime photographs from space. Light disorients birds.  It diverts them from their migratory path, brings them lower in the skies, and can cause them to use precious energy. Because most birds actually migrate at night, you can imagine the magnitude of the problem! Birds may collide with lighted windows at night or window reflections during the day.

Once these night fliers come in for a landing and begin to look for food and shelter, they face the daytime hazards of glass: reflections of trees in windows and false passages through glassed-in courtyards and indoor plantings confuse birds and cause them to collide with glass.

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Urban Green Council Executive Director Russell Unger recently spoke with Bruce Fowle, Founding Principal at FX FOWLE Architects about buildings and bird safety – an issue that has been important to Bruce for many years. Research by leading scientist Daniel Klem [PDF] estimates that at least 100 million and up to 1 billion birds are killed annually by collisions with buildings and other man-made structures in North America alone.

Russell Unger: How did you get involved in this subject?

Bruce Fowle: I would have to attribute most of it to my wife Marcia, who grew up in a birding family. She had been asking me for years what I was doing about all these birds that were killing themselves by colliding with glass – “what are you, Mr. Architect, doing about this?” So I had this guilt trip every time I put up a piece of glass. Then Marcia became Executive Director of New York City Audubon, where she then really put the pressure on. She has since served as President of the Board there and has written a book on birding in the New York City area.

I had spoken out on this issue and made myself known as somebody who was concerned about it from the architectural side, and was invited to speak at a Conference at the Illinois Institute of Technology in Chicago in 2005 (Birds and Buildings). The conference was at IIT for the obvious reason that the original Mies van der Rohe buildings were killing birds by the thousands every year with all that glass; they were the first real all-glass or almost all-glass buildings in the U.S. This conference really kick-started the whole movement, which New York City Audubon picked up on and eventually led to the writing of the Birdsafe Building Guidelines under their auspices. Groups in Chicago and Toronto have made similar efforts.

RU: What’s the scope of the problem?

BF: Well, there’s a scientist–Daniel Klem at Muhlenberg College in Pennsylvania–who has been doing testing and analysis of this for probably 25 years. Based on rough calculations, he has concluded that a billion birds a year are killed in this country alone by colliding with buildings. Most of the birds that collide with glass tend to be the smaller songbird species – and a lot of these species are already endangered because of loss of habitat, climate change and so forth. Glass buildings are one more factor contributing to their demise.

There are three primary conditions that contribute to this problem: lights at night – which draw birds to buildings or other illuminated features during migration; transparency – when a bird sees daylight beyond or an illuminated tree it can roost on and thinks it can fly right through the glass; and reflectivity – when a bird sees sky or vegetation in the reflection from the glass and flies into it.

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