One of the things many species of birds do to become less vulnerable to peregrines is to fly in tight formations. Amazingly, the whole formation seems to turn all at once. Evidently, the wave of movement travels from bird to bird in 17 milliseconds, twice as fast as the reaction time of a sandpiper, which is 38 milliseconds. How do they do it?
Nobody knows Lots of interesting Red Knot information, too.
Paul