If you happen to look up at the sky on Friday night, Sept. 4, you may not notice anything unusual. However, around 219 million birds could be flying over the contiguous United States while most people are sleeping.
The estimate comes from BirdCast, which uses weather radar to follow birds during spring and fall migration. Its forecast shows the most activity across the eastern half of the country.
The birds will be spread across the country as they head south for the winter. More than 80% of North America’s migratory bird species make these trips at night.
EarthSky shared the estimate on Sept. 2. While 219 million birds sound like a lot, BirdCast has tracked much busier nights. A record 1.25 billion birds flew over the country on Oct. 8, 2025.
You Can See How Many Birds Flew Over Your Home
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It may seem strange that weather radar can track birds, but they show up on it just like rain and storms. BirdCast uses those radar signals to estimate how many birds are in the sky and which direction they are going.
The BirdCast Migration Dashboard lets people search by state or county. It shows how many birds crossed the area during the night, along with their average speed and altitude.
Unfortunately, radar cannot identify the type of birds. BirdCast uses nearby sightings reported to eBird to make an educated guess about which species may be passing through.
Turning Off a Few Lights Can Help Them
There are a few things you can do to help the birds. BirdCast recommends turning off any lights you don’t need from dusk until dawn during busy migration periods, as artificial lights can confuse birds or draw them toward buildings, causing them to crash into windows.
You can close your blinds at night to stop indoor light from shining outside or turn off decorative landscape lights.
After Friday night, people can check the website again to see how many birds it estimates actually flew across the country.