New York City in the USA has long been a favourite site for foreign visitors – including millions of birds. But here, as in other North American urban areas, birds face a significant danger: colliding with a building or structure. “It is estimated that some 90,000 birds die annually in New York City because of collisions with buildings,” says Susan Elbin, NYC Audubon’s director of conservation and science.
In the dark, and especially in foggy or rainy weather when birds fly at lower altitudes, the combination of glass and light becomes deadly. Confused by artificial lights, blinded by weather, unable to see glass, or simply exhausted by flying around the lights like moths near a flame, birds can be injured or killed. Fatal Light Awareness Program (FLAP), the Toronto-based conservation society that 
spearheaded the lights-out movement in 1993, is succinct about the threat: “Across North America, more birds die from collisions each year than succumbed to the Exxon Valdez oil spill.” A landmark study conducted by the Field Museum in Chicago showed that by turning the lights off in one building, the number of bird kills dropped by an average of 83 percent.
Growing awareness of light’s fatal attraction to birds has led to action: NYC Audubon inaugurated Lights Out New York in 2005. This year, a number of the city’s iconic buildings such as the Chrysler Building, Rockefeller Center, 501 Lexington Avenue (formerly known as Citigroup Center), Silverstein Properties, The Time Warner Center and the Worldwide Plaza will turn off their lights from midnight to dawn during peak migration season from 1st September to 1st November.
In downtown Chicago, about 100 buildings go dark after 11pm for six months during spring and autum migrations. That is “virtually all of the buildings downtown over 40 stories,” according to Annette Prince, director of Chicago Audubon Society’s Chicago Bird Collision Monitors. And in May, Minnesota’s governor signed a bill that requires structures owned or leased by the state to turn out the lights after midnight during spring and autumn migrations. Other bills supporting Audubon lights-out efforts have been passed or sponsored in Michigan, Massachusetts, and San Francisco.
Not only birds are saved. By following Toronto’s bird-friendly rating system, Metro Hall posted annual savings of $200,000 in energy costs.
Savings in terms of birds’ lives are not as easily measured. In New York City, about thirty volunteers patrol a handful of buildings in the city during migration as part of Project Safe Flight. “The monitoring and research improves our understanding of the causes behind urban bird collisions and suggests ways to prevent bird collisions from occurring,” says Elbin, adding: “The number of birds migrating in autum and spring seemed light this year since few birds were found at the 13 buildings monitored.” (One hundred and fifty eight and 65 bird kills were found, respectively.) White-throated sparrows, common yellowthroats, and ovenbirds were the most numerous species found.
Glenn Phillips, NYC Audubon’s executive director, explains that such low numbers can be misleading and are due in part to New York City’s unique architecture: “We don’t know the true scope of the problem in part because of the set backs of the buildings. With set backs, the birds may fall onto high floors, their bodies never reaching the ground. Other considerations are: predators, wind currents, and traffic. All these factors make it hard for us to collect data and monitor deaths.”
Publications on bird-window collisions can be found here
Keeping birds safe around windows – tips here
