The drones rise all at once, 30 strong, the domes of light on their undercarriages glowing 30 different hues—like luminescent candy sprinkles against the gray, dusky sky. Then they pause, suspended in the air. And after a couple seconds of hovering, they begin to move as one. As the newly-formed flock migrates, its members’ luminous underbellies all change to the same color: green. They've decided to head east.

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