Pacific Slope Flycatcher - Empidonax difficilis
Weighing in at approximately 1/3 OF AN OUNCE, this bird is native to coastal regions of western America, but is replaced in the inland regions by the Cordilleran Flycatcher. These two species were formerly considered a single species known as Western Flycatcher.
In plumage, the Pacific-slope Flycatcher is virtually identical to the Cordilleran Flycatcher, and differs only subtly from most Empidonax flycatchers in North America, but its breeding habitat and call are different.
In summer, the Pacific-slope Flycatcher inhabits deciduous or mixed woodlands, hawking for insects from a hidden perch.
(Most Information from Wikipedia.)