It's fall now and the birds are flying south

Things began to change a few days ago. It wasn't one or two birds visiting the bird bath, it was ten or twelve birds, most of them robins. Up to this time the birds were always, shall we say, polite? Well-behaved, considerate, they queued up, sat in the bird bath, and left. A few days ago the "politeness" was gone, they were bossy, assertive, and pushy. I suspect they were preparing for the long flight south, a last visit to the bird bath and then off they went. We've had some heavy rain this week, Wednesday was the last full day of summer, it's gotten a lot cooler, and the bird bath now sits empty.