Illuminated buildings, especially ones with a lot of glass windows, are deadly for birds. Experts estimate that more than 100 million migrating birds die each year in North America when they become confused by artificial lights at night and fly into the glass. In response, a growing movement to save birds from such fatal collisions has been making a difference in major U.S. cities.
Lights Out DC
Volunteers, mostly amateur birders, travel a 6-kilometer route around downtown Washington, D.C., every day before dawn during migratory seasons. They skirt around the edges of buildings, collecting fallen birds before they are eaten by predators or swept away by cleaning crews.
Lisbeth Fuisz, a director of the Lights Out DC campaign, said the nation's capital has many buildings that pose a danger to migrating birds.
"Large expanses of glass that are lit at night; that have plants inside the building. Because the bird sees the plant in the building, it doesn’t perceive the glass and runs into the windows. And they are attracted to the lights," said Fuisz.
Fuisz explained that the birds most likely to be confused by the light are small songbirds that migrate after dark.
"There is a lot of advantages flying at night, less predators. There is less thermal upheaval so that they can fly more easily. There is also speculation that they navigate using the stars," said Fuisz.
The Lights Out DC campaign urges building owners to switch off unnecessary lights at night during peak migration periods in the spring and fall.
Success switching off lights
Now in its fifth year, the campaign is having some success. After one federal office building with many large glass windows agreed to their request, volunteers saw a two-thirds reduction in the number of bird fatalities there.
Other major U.S. cities have seen similar results, said Ann Lewis, president of City Wildlife, which monitors dead birds through the Lights Out DC program.
"When they had a large campaign in Chicago to get buildings to turn off lights, the bird mortality was reduced by 80 percent there," said Lewis.
This year, volunteers have collected almost 400 birds in the small area of Washington they patrol. The birds are catalogued, frozen and photographed.
"The purpose of collecting birds is to have proof that there is a problem," Lewis explained. "And that is also why we photograph the birds. In the United States, anywhere from 100 million to 1 billion birds are killed by glass collision every year. That is sad."
The birds are donated to the National Museum of Natural History, where Brian Schmidt manages the bird collection. He said the specimens they get can be used for a wide variety of studies.
"One example is researchers can look at carbon and nitrogen signatures and they can determine where these birds hatch, where they grow up, and why they are coming through our section of the country," said Schmidt.
Volunteers hope their efforts will bring increased public interest in the problem, helping to save birds, and energy, as well.