I've never seen them up close but a cousin of mine that is a birder told me they might be grackles. But whatever they are they are leaving the area where they roost at night and going to an area where they feed during the day and then back to their roost in the late afternoon.
I can hear them coming and I love going out on the deck and watching them fly overhead. Not to worry though, because I have never been torpedoed with bird droppings. Evidently they don't poop during flight. Ha.