We still have a Hummer today(Oct. 2nd).  Our local hummers left us on Sept. 25th and did not see a "new" arrival from up north until the 30th of Sept. and that one is still here.  It is only 48 degrees today.  Our summer Hummers feed constantly, but this one is only feeding for about 30 seconds every 15 minutes or so.  I have read that Hummers can go into a state of torpor-a hibernation like state to conserve energy.  I suspect that is what this one is doing.  This ties the record late date for us on seeing Hummers.