We came across this mating pair hovering in a "sun-speck" along the creek-adjacent, woodland trail/road though Mitchell Canyon. To the naked eye it wasn't entirely clear what it was, though I thought I could make out a foamy "nuptial gift" (suggesting a balloon-bearing empidid).
However, I didn't realize it was a mating pair until zooming-in on a photo on the camera display. We observed the two in (roughly) "stationary hover" for over two minutes...don't know how long they were hovering before we noticed them.
After posting this, I noticed @kueda made a very similar observation very nearby about 9 years earlier (with nice accompanying info, and a wonderfully sharp image!)...as did @abmdjoe about 3 weeks earlier here. Seems there's a stable population in the area :-).
A FOS and first yard-list sighting in 23 years of listing, photos by my husband, Randall. Adult male arrived 10/02/23 and remains today, 10/03, very aggressive with local Anna's, guarding both our feeders. We live near Ygnacio Valley Road and Oak Grove in Walnut Creek.
Third evening in a row seen at top of a tall Deodar Cedar . Scarce in this area and early .