The first sighting was a Bewick's Wren on my doorstep, which gave up its bush cover to pishing, and continued to sing in front of me until I tried to approach it further.
A Mourning Cloak (Camberwell Beauty) butterfly landed nicely in a (shaded) clump of oak leaves, which is the best opportunity I've had for this skittish species. In this same location a silent Song Sparrow was also found in the shadows. Many Anna's Hummingbirds were seen all over the place (all females), but for some reason the local hummingbird feeder had still seen no activity. At one point I was checking a House Finch and when I turned around there was literally one hovering right in my face (easily a metre or less away).
I went after some other unfamiliar bird calls, and the only ones I could locate were all Bewick's Wren, which is clearly trying to tell me something. More California Towhees popped up at various points, as did some female House Finches, which was a first for me.
On the way back in a large tree a Vireo-style song brought me to a Robin (American)-sized bird (or European Blackbird if you don't know what an American Robin is like) featuring a distinct supercilia on a sandy brown body which I could not identify at the time. Another hummer in the shade was seen, and when I swore I caught sight of buff-coloured flanks I rechecked this bird and discovered it was actually an Allen's Hummingbird, as opposed to the Anna's I had been seeing so many of, though it was still not inclined to touch the sun. A flock of jumpy brown birds in the valley parallel to the southern part of the estate which I thought were Titmice turned out to be Bushtits on further examination. On the way back I saw the Vireo-song bird a little lower down, and I managed to get a look at the markings better (though it was still very high up in the tree) and most importantly the cone-shaped bill, which brought me to Black-headed Grosbeak as the I.D.