Here's the bird:
This is a Yellow-throated Vireo (Vireo flavifrons), a species that's primarily found in eastern North America. It's only the second time a Yellow-throated Vireo has been observed in Sonoma County, and the first time one has been seen on Bodega Head.
Note the yellow throat and yellow "spectacles" around the eye:
At times this bird was singing loudly:
I'm including two audio recordings below. This is the first time I've recorded a bird singing with my camera. The quality isn't the best (you can hear some background camera noise), but if you want to listen to examples of a Yellow-throated Vireo singing on Bodega Head, here you go!
ytvi2 by nhbh
P.S. The individual phrases in the song are written out in various ways, such as ahweeo, eeyay, ayo, away, oweeah, eeoway — see if you think they match the sounds above.