Least Terns are small fast diving birds. They swoop past so fast that it's hard to get a good look at them until they land, often on a rooftop or nearby rail.

As you watch them, you might notice that they frequently look down into the water; they're looking for little fish. Keep watching; they'll dive when they spot one.

As they fly, you might notice how very long their wings are when fully extended, and their forked tail. If they're too fast, you can see both here in the pictures.

Then - SPLASH, while you were watching one Least Turn, another nearby bird dove:

This time the bird didn't come out of the splash with a fish; but the bird in the next picture did.

Oddly enough, they don't always gobble up their fish, instead, they often fly to another Least Tern that's perched on a rooftop and offer the fish to the other bird. Sometimes the second Tern will take it, but not always. I'm not sure why.

...and in this next one, the Tern got the fish: