This display has been so rarely observed in nature that its function is not known with certainty, though presumably it is a display of aggression or sexual attraction. Both sexes do it, with the color of the crown feathers slightly duller in the female.
Otherwise the bird is an inconspicuous element of the understory avifauna of lowland rain forests and riparian growth on both slopes of Costa Rica. It ranges widely in the American tropics, though recent taxonomic classification changes have divided it into several species, of which the Mexican and Central American populations are considered northern royal flycatcher Onychorhynchus mexicanus.
The crest is usually closed and imparts a distinctive hammerhead appearance. Gray and buff spots on buffy-brown plumage make good camouflage in the dim light of the forest interior.
The appearance is very slender with a length of 17 cm but a weight of only 21 grams, about three-quarters of an ounce.
Diet is flying insects like butterflies, dragonflies, and wasps. These are beaten against a perch to remove wings and stingers.
The nest is also highly distinctive, a slender pendent at least a meter long, invariably over a stream in the forest, and made of woven plant fibers and rootlets. Despite the long tail, the nest pouch is part way down the pendent with a narrow slit for an entrance.