Bird migration through the Windy City

AN 628373 Beecher window killed birds ca1975 200ppi
April 20, 2021

You might not associate a big city like Chicago with a nature lover’s hot spot, but the Windy City is a great location for bird watchers. Chicago sits in one of the major bird migratory routes in North America, known as the Mississippi Flyway, so each spring and fall, there are hundreds of species that fly across the region.

Migration NA 2

Migration routes of North America. Notice the Mississippi Flyway indicated in blue.

Migration season presents some major obstacles for birds flying through the city, though. While Chicago is famous for a tradition of innovative architecture, many of the city’s tall, glass buildings present a serious, and oftentimes fatal, obstacle for migrating birds. The Chicago Bird Collision Monitors estimates that thousands of birds are killed or injured each year by colliding with windows in downtown Chicago.

Window kill birds 2018 scaled

Birds killed by window impact and added into the Academy’s scientific collections in 2018. Chicago Academy of Sciences.

Birds fly using the natural light emitted from the sun, stars, and moon to navigate. Especially for species migrating at night, artificial light from human structures interferes with the natural light sources birds use. William Beecher (1914-2002), director of the Chicago Academy of Sciences from 1958 to 1982 and an avid ornithologist and photographer, studied bird migrations and the issue of bird window collisions in the Chicago region. His work, and that of other scientists, is being continued today and shows that light emitted from buildings at night interferes with birds’ navigation abilities, causing disorientation and potentially fatal collisions with building windows.

AN 628373 Beecher window killed birds ca1975 200ppi

William Beecher looking at window killed birds, ca 1975. Chicago Academy of Sciences.

The Lights Out program in Chicago was created to help protect birds during migration season and encourages building owners to dim or turn off building lights at night. Help birds navigate their way safely through the city. Turn off your lights to reduce light pollution and help prevent birds from hitting windows.

Many thanks to U.S. Forest Service – International Programs for providing support for our specimen preparation work with window-kill birds and other programming.

Want to Learn More?

Lights Out Chicago. Chicago Audubon Society.

Lights Out Chicago. City of Chicago.,and%20the%20City%20of%20Chicago.

Lights Out Chicago. Chicago Bird Collision Monitors.

Lights Out. Bird Cast.

Migration Celebration 2020. Cornell Lab of Ornithology. video – Lights Out for Birds – Protect Their Journeys,

Lights Out. National Audubon Society.

“Light Pollution Poses Threat to Migrating Birds.” International Dark-Sky Association. May 9, 2019.,can%20result%20in%20fatal%20collisions.

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