This bird is a Bewick's Wren. (they are quite opportunistic nesters!)
Besides Bewick's, house and Pacific wrens are the only two other similar wrens in your area. house wrens have a pale, almost invisible eyebrow stripe, while pacific wrens are identifiable by their plump, almost chicken-like body. (Bewick's has a bold eyebrow stripe.)
Marsh Wrens are also in your area and are identified by their heavy barring on wings and rattle like call.
1. house wren
2. pacific wren
3. bewick's wren
4. marsh wren