In June of 2022, Adé Ben-Salahuddin worked as a volunteer research assistant on a tiny island off the coast of Maine at a Common Tern breeding colony. Every once in a while, the colony would suddenly go dead silent as all the adult terns took flight and dove over the rocky cliffs, returning soon afterward. This strange behavior is called a “dread,” and sometimes occurs without a predator nearby. It remains unclear why terns do it.

More info and transcript at BirdNote.org. 

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