Something similar to the displacement happened with birds during vacation recently. I was just relaxing on a porch, and one by one groups of birds would occupy the lawn for a while. It must've been four or five different species, in groups from one (only the kingfisher) to six or seven finches of some sort. It seemed strangely orderly, in that each group seemed to stay about the same amount of time, and none of the groups ever met - the new group would always swoop in shortly after the last one. There was no bird feed to be had there. I can't be sure, but it seemed the groups were actually rotating rather than new ones every time.