Total birds

39700 Birds have crossed St. Louis County so far tonight (est.)

Starting: Sun, Aug 10, 2025, 8:30 PM CDT

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Live migration traffic

159,400 Birds now in flight (est.)
Direction: SSE
Speed: 17 mph
Altitude: 2,300 ft
Recorded: Sun, Aug 10, 2025, 11:10 PM CDT
Not all birds may fully cross a region in one night, resulting in a greater number of birds in flight than total birds crossed.

Here's what's happened so far tonight...

Birds in flight

Tonight, Aug 10
Historic
10 PM CDT1 AM4 AM0450K

Birds usually begin to migrate 30 to 45 minutes after sunset, with the greatest number in flight two to three hours later.

Flight direction and speed

10 PM CDT1 AM4 AM026 mph

Birds tend to migrate southward in autumn, but seasonal timing, weather, and geography alter their flight directions and speeds.

Altitude

Tonight, Aug 10
Historic
10 PM CDT1 AM4 AM04500 ft

Migrating birds regularly fly up to 10,000 feet above ground, although seasonal timing and weather conditions dramatically impact their distributions.

Note: Direction, speed, and altitude may be unreliable when the number of birds in flight is low. In such cases, chart data may include gaps.

And so far this season...

Birds in flight (nightly avg.)

Fall 2025
Historic
AugSepOctNov01.6M

During fall migration, most birds pass through the contiguous U.S. from early September through October.

Total birds crossed

Fall 2025
Historic
AugSepOctNov0300M

This is the estimated total number of birds that have fully crossed this region. The curve rises quickly during peak migration and levels off at the end of the season.

Expected nocturnal migrants

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Nocturnally migrating species most likely to arrive or depart this region at this time of year, based on frequency of observations

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Cornell Lab of Ornithology
Colorado State University
UMass Amherst