Response to Wendy and anyone else who wondered what suggestions were given! So far I think I had Western Wood Pewee, Say's Phoebe, Lesser Goldfinch, and Spotted Towhee. The closest was the Pewee and the Phoebe, but still no cigar. The Spotted Towhee (that I *still* think of as Rufous-Sided!) was actually the answer to another ID-by-sound question I had several months ago, wow!
This bird from yesterday...I started thinking it sounded so similar to a sound I have heard of Western Bluebirds, often when they fly. But it's just the one note! I looked up more audio samples and so far that's the closest of all. Interesting that even in one species, there are so many different sounds!
The Edge of SLO
Dreamzville.com (Home of Dreamzville Radio), San Luis Obispo.