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Creatures of the Night: Fall Bird Migration

September 24, 2025

By: Erin Parker, Interpretive Services Supervisor

Warm days, cool nights, and leaves just hinting at orange and red- fall has arrived on the calendar and the landscape! While many animal species can be observed fueling up on flowers (like monarch butterflies) or gathering winter food to store away (like squirrels) or simply fattening up before a long winter hibernation (ground hogs), there’s a major movement underway that may be nearly invisible to most people.

Early fall is peak bird migration season, as they follow food sources and open water southward ahead of the first hard frosts. While you may see soaring raptors or even huge flocks of blue jays migrating during the day, the majority of birds actually migrate after the sun goes down!

Bird migration likely takes place at night for several reasons: fewer aerial predators, stability in the atmosphere without the sun’s uneven heating of surfaces, utilizing stars and the moon for navigation, and even that cooler nighttime temperatures can help keep active birds cooler on their long journeys.

Nighttime Migration

While most humans don’t think about darkness as a “habitat”, it provides the resources that many organisms need to thrive. And nocturnal migration of birds is not a small event- sometimes millions of birds are in flight on a good night when weather conditions are clear and winds are blowing favorably to help them wing their way south.

Because birds utilize the glow of stars and moon to help with navigation, human-created light sources in cities and suburbs can be disturbing…if not deadly. Human light sources can draw birds in, causing them to crash into buildings, towers, and windows. If they don’t crash into the light source, they can exhaust themselves flying in disoriented circles in confusion.

Artificial light sources, like these of the skyline of Detroit, can cause confusion, exhaustion, and even death of migrating birds adapted to navigating by the moon and stars.

Action Steps to Protect Birds

Southeast Michigan is at the intersection of two busy flyways, or migratory routes, for birds, Birds utilize natural landmarks like rivers and mountain ranges along with their nighttime navigations cues to help them head south in the fall and back north again in the spring. Michigan has two major flyways that intersect here, meaning that migration numbers can be vast. Both the Atlantic flyway and Mississippi flyway are major pathways for bird migration that help birds navigate while avoiding large geographic obstacles like the Great Lakes or large mountain chains.

Many cities and communities around the world, including Detroit, participate in “Lights Out for Birds” events during the spring and fall migrations. These initiatives encourage residents, businesses, and industries to turn off non-essential lights from roughly 11 p.m. to 6 a.m. during the migration windows each spring and fall. Even turning off lights for 20-minute stretches can reduce groups of birds drawn in and circling bright city lights, allowing them to regain their sense of direction and continue on their migration safely.

After spending the spring and summer in Michigan, yellow warblers and other songbirds follow the insects, flowers, nectar and other food sources south. These tiny birds typically fly at night while navigating by the light of the moon and stars.

Along with turning off lights completely, there are additional ways to reduce the impacts of artificial lights on wildlife during migration season and beyond:

  • Lighting for humans should point down to the ground and be topped with a shield or cone that prevents light from aiming up towards the sky.
  • “Warmer” colored lights or colored lighting, such as red or blue, can make artificial lighting less confusing to birds
  • Flashing lights and motion-sensing lights, instead of static light sources, can be used as the changing pattern of light and dark doesn’t confuse migrating birds and other wildlife
  • Dimming lights, closing blinds or curtains, or having lights on a timer that allows them to be on for people and off as the night gets later, can all help homes and businesses reduce bird migration mortality

Resources to Learn More:

 

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