Like an expert angler, a tern can read the surface of the water to find where to catch its next fish. Scientists piloted a drone to track the flight paths of terns on the hunt. The terns sought out turbulent water. A vortex formed by colliding currents traps fish near the surface, where terns can snap them up. Terns fly toward bubbly upwellings to see if the rising water brings prey animals along with it.

More info and transcript at BirdNote.org. 

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