One of the stops we made on my last field trip in Louisiana was at Lacassine NWR. The habitat there was mostly marsh and mudflats, attracting lots of ducks, wading birds and shore birds.
An interesting behavior exhibited by the shore birds occurred whenever a bird of prey would fly over the mudflats. The flocks of sandpipers would take off and fly around in a big "blob". In this particular example the bird of prey was a Peregrine Falcon (not in the picture). He appeared a couple of times, and each time the shore birds took off and flew around in their "blob", eventually landing again when the collective decided that the danger had passed. The guide for our field trip called this phenomenon "scrambling the mudflats" because after everything landed, you had to go through and re-identify/re-locate all the birds since they were all in different places than before.