The melancholy of September is necessary, then, part of the cycle. It's the only way (short of their year-round residency) to see them again. They must leave in order to return.
I thought I had seen the last of the hummingbirds a week or more ago, but on Monday I spied a small jeweled creature first at the feeder and then, moments later, hovering right in front of me.
Perhaps it had come to say thank you ... or perhaps to say goodbye.