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. Want more BirdNote? Subscribe to our weekly newsletter. Sign up for BirdNote+ to get ad-free listening and other perks. BirdNote is a nonprofit. Your tax-deductible gift makes these shows possible.