On Sept. 14, thousands of tree swallows gathered above Parker River National Wildlife Refuge in Newburyport, MA, forming a swirling “birdnado” as they fed and prepared to roost. The U.S. Fish and Wildlife Service says such massings are an annual fall migration phenomenon, sometimes in the tens of thousands. Experts note tree swallows are highly social and can form flocks that number into the hundreds of thousands as they migrate down the Atlantic coast to wintering grounds.
‘Birdnado’: Thousands of Tree Swallows Form a Swirling Flock Over Parker River Refuge
Image Credit: U.S. Department of the Interior on X.
On Sept. 14, thousands of tree swallows filled the sky above Parker River National Wildlife Refuge in Newburyport, Massachusetts, creating a dramatic, tornado-like swirl of birds that the U.S. Department of the Interior playfully dubbed a “birdnado.” The agency shared video of the spectacle showing an immense flock gathering above the marsh before continuing its southbound migration.
What Happened
The birds paused at the refuge to feed on insects and berries and to roost for the night. In the footage, swallows circle above the marsh as more individuals drop in from the sky to settle — a scene that can look remarkably like a living, swirling tornado.
Why It’s Not Unusual
This impressive massing is a regular seasonal event at Parker River. The U.S. Fish and Wildlife Service describes these gatherings as an annual phenomenon: during fall migration tens of thousands of tree swallows can concentrate at the refuge while hunting or preparing to roost. Mass Audubon notes that the tree swallow is Massachusetts’ most abundant swallow, and huge coastal flocks are typical in autumn.
Biology And Migration
Tree swallows are highly social outside the breeding season. The Cornell Lab of Ornithology reports that migrating and wintering flocks can sometimes number in the hundreds of thousands. Eastern tree swallows typically migrate down the Atlantic coast to wintering grounds in Florida and Central America, and Parker River’s marshes provide an important stopover to rest and refuel.
Watch: The Department of the Interior posted video of the event — a striking reminder that routine natural behaviors can be spectacular when thousands of animals act in concert.
Watch the Interior’s video of the birdnado.
Why it matters: Large, coordinated gatherings like this highlight the importance of coastal stopover habitats for migratory birds and underscore the value of protected areas such as Parker River NWR.
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