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September 14, 2020

More than 50,000 birds to fly over Philly on Monday night

The 'high intensity' migration is the result of numerous species making the annual trek south

Wildlife Birds
Bird Migration Philly Sierra Narvaeth/

BirdCast, a migration tool that tracks and forecasts bird movements, projects a high intensity nocturnal migration of several species over Philadelphia on Monday night into Tuesday morning.

Some 9 million birds are in the midst of a mass migration across the United States, with a flyover above Philadelphia on track for Monday night.

BirdCast, a migration tool led by Cornell University's Lab of Ornithology, projects a swell of as many as 53,400 birds over the city this evening.

To put that in perspective, roughly 3,000 birds flew over Philly on Sunday night ahead of the pack.

Conservation Action Alert! Almost 900 million birds are predicted to be migrating across the United States over the...

Posted by Pennsylvania Natural Heritage Program (PNHP) on Sunday, September 13, 2020

The species making the trek include the black-and-white warbler, scarlet tanager, wood thrush, and golden-winged warbler. They are all considered in high need of conservation.

"Remember that high intensity nocturnal migration may not necessarily mean an excellent day of birding," BirdCast says on its website. "Rather, it means that large numbers of birds are migrating or predicted to migrate at night!"

September is considered a peak migration month for millions of songbirds who leave North America for tropical latitudes. They opt to fly at night because the cooler air provides more stability and efficiency, preventing them from overheating as they travel long distances. Warblers, for instance, may travel up to 200 miles in a night.

Philadelphia residents hoping to get a good view may not have the best natural conditions this year. The moon, which helps backlight migrating birds when using binoculars, is in a waning crescent phase. On the other hand, the weather forecast calls for clear skies. 

BirdCast suggests the best way to see the migration is to listen out your window and watch the sky for activity.

The Pennsylvania Natural Heritage Program advised residents to turn off outdoor lights wherever possible.

"At night, artificial lights can confuse birds and cause them to become disoriented or fly into buildings," PNHP said on Facebook. "To protect these migrating birds, turn off as many of your outdoor lights as possible from 11 p.m. to 6 a.m ... This small action can have a big impact on the safety of our migratory species!"

To get a bird forecast for cities and towns outside Philly, head over to BirdCast and enter your location. You can also check out real-time migration maps.