Missing Mockers

As I observed the goings-on at the feeder stations last night---a swirl of House Finches, Mourning Doves, Gray Catbirds, and Northern Cardinals, mostly---it occurred to me that I hadn't seen a Mockingbird in quite some time. They're a reasonably common sight here all year. And indeed, my logbook in hand, I could see that nary a Mocker had been observed since the very end of May. What could be happening? Have the Catbirds driven them off? or are the Mockers getting more appealing food elsewhere? Some homeowners would be quite happy to be rid of these sometimes aggressive Mimids. But they are part of the extended family; the restless middle children, perhaps. You may find them trying, but you love them all the same. I am keeping my eyes extra-open. This is an interesting mystery.