LIGHTS OUT

Tall buildings with bright lights at night are a magical sight. In fact, it is one of the attractions of North America's big cities. However, few people are aware that those brightly lit buildings also have a dark side to them: they can be very dangerous for the millions of birds flying through those cities during migration season.(lines 1–4)
Twice a year, in spring and autumn, millions of birds fly through the skies of North America. In the spring they fly north and in the autumn they fly south. Many of them are nocturnal birds, meaning they travel at night. When they fly near buildings, the bright lights in the windows often confuse them. They crash into the walls or into the glass windows and get hurt. Other birds lose their sense of direction and fly around in circles until they get so tired that they fall to the ground. According to experts, as many as 100 million birds are harmed every year in North America because of nighttime lights. In the city of Chicago alone, thousands of birds are found injured or dead every day during the migration season.(lines 5–17)
Chicago was one of the first cities to try to solve the problem with its "Lights Out" program. As part of this program, building managers in tall office buildings are encouraged to switch off the lights late at night during the migration season. People who live on the upper floors of tall buildings are reminded to turn off their lights before going to sleep. By taking these steps, they save on electricity so they also pay less for it. Although there is still much to do, this program has had some success: there are fewer dead or injured birds in Chicago. Other cities, like Toronto, have similar programs but they are managed by environmental groups alone, while in Chicago, the city authorities participate in managing the program.(lines 18–25)
As Toronto environmentalist Michael Mesure points out, light pollution hurts not only birds but other wildlife too. It even prevents people who live in the city from being able to see the stars. So the "Lights Out" program may have benefits far beyond helping migrating birds.(lines 26–28)