The Cordilleran flycatcher, Empidonax occidentalis, is a small bird that breeds in the western United States, Mexico, and a small area of southwestern Canada. The species migrates to warmer areas for winter, with most individuals wintering in Mexico. It is a fairly common breeder in Utah, where it prefers forest, woodland, and riparian habitats.
Nests are built on steep banks, on cliffs, and around man-made structures. A clutch of three or four eggs is laid in early summer; the female then incubates the eggs for about two weeks. The young are tended by both parents and fledge at 14 to 18 days of age.
The Cordilleran flycatcher is active during the day. It eats insects that are either captured in the air or gleaned from vegetation.