As with other royal flycatchers, the Pacific royal flycatcher is thought to feed on insects, particularly large flying insects such as dragonflies, which are snapped up in flight or gleaned from foliage (3). Although usually solitary or in pairs (5), these birds have also frequently been observed in small, mixed-species flocks (2).
Nests are typically suspended from overhanging branches and vines above shady streams, and have been found between January and April, with a juvenile collected in May (2) (5). The territory is defended by the male while the female incubates the eggs and tends to the chicks (3). During display, performed during courtship and aggressive encounters, the crest is erected and fully spread, while the head is rhythmically swayed from side to side and the bill is slowly opened and closed to reveal a bright mouth lining (3) (4).