One of the Empidonax flycatchers, a notoriously difficult group to identify. By location, either Hammond's Flycatcher or Pacific-slope Flycatcher (a.k.a. Western Flycatcher). Slight preference for Hammond's, but the scientific name of Pacific-slope (Empidonax difficilis) says it all!
Gardenpom, great picture! And a lovely bird. I'm still excited over seeing the Western Flycatcher and sure do hope to see one again. I haven't been home at all so haven't had a chance to sit and watch.