Autumn Bird Migration: What to Watch in September's Skies

Field report

From the first flocks of geese overhead to the last hummingbirds departing, this month is all about migration.

Wildlife Photography / Getty Images

By mid-September, the first big waves of migrating songbirds sweep through. Warblers and vireos flit through the canopy, snatching insects before pressing south. The dawn chorus shifts—thrushes and tanagers join the residents, and the morning air carries a new, restless urgency.

If you want a migration hotspotA volcanic region fed by a mantle plume rising from deep below the tectonic plate., try heading to a coastal headland or lakeshore. Birds funnel along these natural corridors, especially after a cold front passes. Look for flocks of broad-winged hawks spiraling upward on columns of rising air called kettles. On a good day, thousands of hawks stream overhead, their silhouettes sharp against crisp blue sky. A pair of binoculars helps, but on peak days you can see them with the naked eye!

If you happen to live along a flyway, you can expect the show to improve over the coming weeks. Ornithologists estimate that billions of birds cross North America each fall, many traveling at night under the cover of darkness. You can hear their flight calls—thin, high-pitched chips and zeeps—if you step outside after midnight on a September night. Radar even tracks these massive nocturnal movements online.

Ruby-Throated Hummingbirds Fuel Up Before the Gulf Crossing (Sept. 10)

For those with flower gardens, ruby-throated hummingbirds have been practically impossible to miss over the last several weeks. These tiny migrants—weighing less than a nickel—have been draining nectar feeders at a furious pace, doubling their body weight in fat reserves. By mid-September, the males depart first, their iridescent throats catching the last of the afternoon light as they vanish southward.

But this dazzling display won't last indefinitely. After the adults leave, juveniles linger, still filling up on late-blooming jewelweed and cardinal flower. Over time, even the stragglers will vanish, and your feeders will sit untouched until spring. So if you haven't already, make sure to keep those feeders full and fresh. It's a backyard spectacle that's hard to ignore!

In 2022, while serving as Friends of Pando's artist-in-residence, Rice used a variety of microphones to record Pando’s leaves, birds, and weather.

Sandhill cranes, some of the tallest birds in North America, begin assembling at traditional staging grounds in mid-September. Despite standing nearly four feet tall with a wingspan over six feet, these elegant gray birds can be remarkably hard to spot in harvested cornfields where they feed. To find them, listen first—their rolling, trumpeting calls carry for over a mile. Then scan the fields with binoculars or a spotting scope.

Fun fact: Sandhill cranes are among the oldest living bird species on Earth. A fossil found in Nebraska dated to 10 million years ago is nearly identical to modern cranes. Have your birding companions ponder that while you watch these ancient creatures dance, bow, and toss bits of corn into the air during their exuberant courtship displays.

Bid Adieu to Summer and Welcome the Fall Equinox (Sept. 23)

The first day of autumn in the Northern Hemisphere will officially arrive on this day, and for our friends in the Southern Hemisphere, it's the first day of spring! At 2:49 a.m. EDT, we'll say goodbye to the balmy days of summer and welcome the start of fall with the autumnal equinox. The equinox happens the moment the sun crosses the celestial equator, an imaginary line that corresponds to Earth's equator, and for wildlife, it triggers a cascade of behavioral shifts.

In anticipation of the colder months ahead, the fall equinox offers an important reminder to fill your bird feeders, plant native wildflowers for next year's pollinators, and dust off your field guides. According to the Farmers' Almanac's long-range forecast (which, like any long-range weather forecast, should be taken with a grain of salt), the coming winter will make "cold-weather fans rejoice," with "more snow and low temperatures nationwide"—tough for ground-feeding birds, so stock up on suet!

Watch for Nighthawks Streaming South at Dusk (Sept. 22)

“It’s similar to two cans connected by a string,” Rice said. “Except there are 47,000 cans connected by a huge root system.”

Likewise, during a thunderstorm, sounds recorded by the hydrophone increased in relation to the intensity of the storm.

Common nighthawks, those odd, buoyant birds with pointed wings and white wing stripes, make themselves easier to spot in late September as migration peaks. On favorable evenings, flocks of dozens—even hundreds—stream over cities and towns, swooping after flying insects in the lingering twilight. The only downside is that they pass quickly, often high overhead, so find an open spot with a wide view of the sky and scan upward as the sun sets.