Cassin's kingbird, Tyrannus vociferans, is an aggressive fly-catcher that breeds in much of the western United States, as well as in Mexico. It winters from southern Baja California and northern Mexico southward into central Guatemala. It breeds in mixed deciduous-coniferous woodlands, in dry savannah, or in scrubby areas . It is a common summer resident along wooded riparian areas in southern Utah; it may also be found in forests of juniper or ponderosa pine.
Cassin's kingbirds establish territories, and they will aggressively defend them from other birds such as crows and hawks. Cassin's kingbird feeds primarily on insects and berries. It forages from perches near its nest and captures insects in flight. Males perform a frenzied courtship flight for the females, and then a monogamous pair bond is formed. A cup-shaped nest is constructed close to the trunk of a deciduous tree, and the female incubates her clutch of three to four eggs for about three weeks. The young are born naked and blind, and both parents care for the young. The chicks leave the nest after about sixteen days.
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