It’s a bird, it’s a plane, it’s ... butterflies?
A radar signature was initially thought by the National Weather Service in Boulder, Colo., to depict the migration of birds, according to The Denver Post.
However, later on, meteorologists determined that the signature was likely caused by a 70-mile-wide wave of migrating butterflies after they received many reports about sightings, The Associated Press said. Painted lady butterflies – sometimes mistaken for monarchs – were reported drifting with the wind, according to the AP.
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“Insects rarely produce such a coherent radar signature,” the U.S. National Weather Service Denver/Boulder Colorado explained on Facebook on Wednesday. “Migrating birds do all the time.
“Migrating butterflies in high quantities explains it. Today, the butterflies are staying close to the ground.”