WAITING...

This little hummer had me worried today.  He just sat on the feeder for minutes at a time - way longer than his usual quick drink and nervous flutter.  I get that they act on instinct, but this one seemed to actually be waiting for something.  If so, I thought it was smart of him to wait at a feeder where it was likely another hummer would stop by.  I'm guessing that, as a juvenile, he's one of the last to migrate.  I wondered if he just didn't know what to do and is waiting for another hummer to show up to give him the signal to join the group to start their migration.   There used to be 3 or 4 dive-bombing each other for a chance at the feeder, then eventually seeing one was rare, and now there's just this one little guy.  Does anyone know how they realize when to start migrating, and how they know where to go?   One of Nature's mysteries!