Earth Hour: Turning Lights Off Reduces Greenhouse Gas Emissions
and Protects Migratory Birds

American Bird Conservancy supports Earthhour, the worldwide movement to turn lights off for one hour on March 29th from 8:00-9:00 p.m. World Wildlife Fund is coordinating this global event to focus attention on the urgent need to address global warming and reduce greenhouse gas emissions. Cities, individuals and businesses around the world have registered to participate. We urge you to do the same at www.earthhour.org

Turning out lights will save energy and benefit migratory birds, particularly if lights are turned out for the duration of the night in tall buildings and cities during Spring and Fall migration. This is because many birds have evolved to migrate in dark skies, navigating their journeys by natural light from the stars and moon. Starlight is made vastly less visible by light pollution from our towns and cities, and thus interferes with the birds’ ability to reach their destinations safely. The following map illustrates light pollution for portions of the western hemisphere and shows massive illumination of vast areas of the continent.

Maps of Artificial Night Sky Brightness in North America. Map Credit: P. Cinzano, F. Falchi (University of Padova), C. D. Elvidge (NOAA National Geophysical Data Center, Boulder). Copyright Royal Astronomical Society. Reproduced from the Monthly Notices of the RAS by permission of Blackwell Science.

Two photos of the Chicago skyline taken before and after 11 pm on the same fall night in 2003. Photo: Eric Fogleman

Particularly during periods of low cloud cover or inclement weather, birds become attracted to, and disoriented by, lit structures including buildings, communications towers, and offshore drilling platforms see www.abcbirds.org; www.flap.org. Trapped in these light fields, they circle these structures endlessly, often colliding with each other, the structure itself, or supporting elements such as guy wires. Others collapse from exhaustion or are forced to land in the middle of the city to rest, where they are then exposed to hazards such as collisions with windows, which kill up to 100 million birds per year in the United States alone. Toronto and Chicago were the first to initiate Lights Out programs. In Chicago, turning off city lights in many downtown office buildings reduced bird kills by 80% during migration. Voluntary Lights Out programs have been adopted in other US cities including Minneapolis/St. Paul, Detroit and New York. ABC will be working to support the expansion of Lights Out programs to additional American cities to help migratory birds, such as the Wood Thrush pictured here, safely navigate their journeys to and from their breeding grounds.

Wood Thrush. Photo: USFWS

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