Aegolius is a genus of small true owls. The genus name is from Latin; aegolius is a type of screech owl thought to be a bird of ill omen, and funereus means "funereal". Three of the extant species are restricted to the New World, but the Boreal Owl has a circumpolar range through North America, Eurasia, the Alps and the Rockies. The species are: Aegolius owls are small, dumpy, short tailed and broad winged, with large round facial discs. The species varies from 18–27 cm in length. Aegolius owls breed in tree holes laying several eggs. They have repetitive whistling calls in the breeding season.