i always thought mid to late summer was the best chance of seeing hummers at my feeders. i keep filling up the feeders but i never see any hummers.i saw some earlier this summer now it seems like they have vanished. used to be , i could refill the feeders and if i waited by the right window at least 15-20 min. i would see one or two.i just went out and marked the level of my feeders to see if the levels are indeed going down. i have rose of sharon, abelia and red honeysuckle nearby. what's happening? i live basically at the ga/tn line. thank you.