Every year, lots of birds are killed when they fly into buildings.1 does this happen? The answer is glass. Birds fly into windows and tall buildings. These windows and tall buildings are all covered by glass.
Many birds fly from one place to another. Most of the time, they2 in nature, such as forests and wetlands. These birds have no idea what glass is. They3 see small trees and flowers inside a window. They want4 on these plants. The birds do not know there 5 glass between them and the plants. So they fly right into the glass.
Some birds fly at night. They use the moon and stars to help 6 find the right direction. Tall buildings with lights on at night can make the birds unable to know the right direction. This is 7 big problem. The birds can see the light, 8 they cannot tell that the light is coming from inside a building. They fly toward the light and crash into a building. Many mornings, there might be some dead birds lying 9 the ground.
People are trying to work out the problem. 10 office buildings now turn off their lights at night. This helps reduce the number of birds that fly into buildings and it also helps save energy.
