Northern California have tons of warblers. So far I have seen Wilson's Warblers, Yellow-Rumped Warblers, and Townsend's Warblers. The Townsend's Warblers are distinguishable by their raccoon eyes.
These guys are very shy. I saw them several times before I could ever capture a picture. The picture above was the only picture that I captured for six months. Last week, one stayed still long enough for me to capture more than one picture!