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Question of the Week

Q. Why do migratory birds crash into buildings at night and how can people prevent it from happening?

A. Even in the best of circumstances, spring and fall are dangerous times for migrating birds. When they migrate over major cities, the risks increase. Many potentially fatal collisions happen when a nocturnal migrant hits a lighted high-rise jutting into their airspace. Some of these collisions are random, but much more often the lighted windows lure birds to their deaths.

The reasons are not entirely understood, but nocturnal migrants often navigate by the stars and illuminated windows and other night lights often divert them from their original flight paths, especially in low-ceiling or foggy conditions. The birds mill about in the lighted area, where they collide with the lighted structure or with one another. In addition to buildings, communications towers and radio antennas pose similar threats. Hundreds or thousands of dead birds may litter city streets after a wave of migrants has passed through. In all, an estimated 100 million to 1 billion birds die each year in North America from colliding with structures.

As we learn more about where, when and how these nighttime collisions happen, we are also learning how we can prevent them. Since 1993, the Fatal Light Awareness Program (FLAP), a Toronto-based conservation society, has spearheaded “Lights Out” programs across North America, calling for buildings in major cities to turn out all of their lights each night during peak migration times. One study conducted by the Field Museum in Chicago showed that in one building, turning the lights off reduced the number of bird kills by an average of 83 percent.

There are other reasons that birds collide with buildings, and especially with windows. Visit our Window Collisions page for more on the subject, and other window treatments that help prevent collisions in residential areas.

Past Questions of the Week

Q. Where can I go to watch hawk migration?

Q. How do birds prepare for long migrations?

Q. Should I stop feeding birds in fall so they can start their migration?

Q. What is the Migratory Bird Treaty Act?

Q. After birds leave a nest, can I clean out the nest for future use?

Q. How can I keep birds from hitting my windows?

Q. Why do woodpeckers like to hammer on houses?

Q. I’m seeing fewer birds in my yard. Is something affecting their populations?

Q. I found a baby bird. What should I do?

Q. I found a nest near my house and want to observe it but I am worried about disturbing it. Can you give me any advice?

Q. Sometimes I see little birds going after a big bird. Why do they do this?

Q. My feeders are being overrun with pigeons and blackbirds who eat all the food and keep the smaller birds away. What can I do?

Q. How can I share my bird photos with the Lab?

Q. How do I keep the squirrels in my yard away from my feeders and bird seed?

Q. Where can I go to watch hawk migration?

Q. Should I stop feeding hummingbirds in the fall so that they will migrate?

Q. After birds leave a nest, can I clean out the nest for future use?

Q. I live in a high-rise apartment with a tiny balcony. Is there any way I can attract birds all the way up on the 17th floor?

Merlin Bird ID app
Be a Better Birder Tutorial 3