Found originally by Nico Stuurman, this is a rare stray to California normally breeding in Eastern North America and wintering in Mexico and Central America. It is the smallest member of the "Empidonax" genus of flycatchers, a confusing array of species with a similar set of field marks including wing-bars and an eyering. Identification relies on a combination of other more subtle features. This is a relatively colorless big-headed, short-tailed flycatcher with contrasting white wing-bars and tertial fringes against a dark background. Western North American species typically have a less contrasting wing pattern. Note particularly the short primary projection which allows the bird to pump its tail up without flicking its wings. The bill is usually very short but relatively broad with a pale lower mandible as seen here. They don't sing in the winter but they do have a "wit" call-note which sounds a bit more snappy than similar species.
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