Elf Owls have many distinct vocalisations. Five to 20 notes are given during each sequence and calling can be almost continuous through the night. Calling is most intense during early evening and near dawn, on moonlit spring nights. A shorter version of this song attracts females to potential nest sites. Mated pairs may also duet, but the female's song is softer and shorter.
Nestlings give a repetitive rasping call when hungry.
Elf Owls hunt small, weak prey because their relatively weak feet and talons. Virtually all prey are arthropods - mainly insects and scorpions, although they likely take the odd mouse or small bird also. There have been a few rare records of small lizards and small snakes being taken. Other common foods include grasshoppers, locusts, mantids, fly larvae, caterpillars, centipedes, and cicadas. Most prey is captured in flight as Elf Owls are very manoeuvrable in flight.